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1.
J Dairy Sci ; 107(3): 1788-1804, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37806631

RESUMO

The objective was to compare pregnancy per service event (P/S) in lactating dairy cows following timed artificial insemination (AI) or timed embryo transfer (ET) using either fresh or frozen in vitro-produced embryos. Oocytes were collected once per week for up to 9 wk using transvaginal ovum pick-up from elite dairy donors (ET-DAIRY; n = 40; Holstein-Friesian and Jersey) and elite beef donors (ET-ELITE-BEEF; n = 21; Angus). Both ET-DAIRY and ET-ELITE-BEEF donors consisted of heifers and cows. In addition, oocytes were collected from the ovaries of beef heifers of known pedigree following slaughter at a commercial abattoir (ET-COMM-BEEF; n = 119). Following in vitro maturation and fertilization, presumptive zygotes were cultured in vitro to the blastocyst stage. Grade 1 blastocysts were either transferred fresh or frozen for on-farm thawing and direct transfer. A total of 1,106 recipient cows (all lactating, predominantly Holstein-Friesian) located on 16 herdlets were blocked based on parity, calving date, and Economic Breeding Index, and randomly assigned to receive AI (n = 243) or ET (n = 863) after estrous synchronization with a 10-d Progesterone-synch protocol. Cows assigned to ET were further randomized to receive fresh (n = 187) or frozen (n = 178) ET-ELITE-BEEF embryos, fresh (n = 169) or frozen (n = 162) ET-DAIRY embryos, or fresh (n = 80) or frozen (n = 87) ET-COMM-BEEF embryos. Pregnancy was diagnosed using transrectal ultrasound on d 32 to 35 after synchronized ovulation and confirmed on d 62 to 65, at which time fetal sex was determined. Pregnancy per service event at d 32 was not different between AI (48.8%) and ET (48.9%) and did not differ between dairy and beef embryos (50.3% vs. 48.1%, respectively). However, P/S was less on d 32 following transfer of frozen embryos (41.6%) compared with fresh embryos (56.1%). Pregnancy loss between d 32 and 62 was greater for ET (15.1%) compared with AI (4.7%), with greater losses observed for frozen beef (18.5%), fresh beef (17.3%), and frozen dairy (19.2%) compared with fresh dairy (6.0%) embryos. Serum progesterone (P4) concentration on d 7 was associated with P/S at d 32 and 62. Cows in the quartile with the least serum P4 concentrations (quartile 1) had less probability of being pregnant on d 32 (33.4%) compared with cows in the 3 upper quartiles for serum P4 (45.7%, 55.6%, and 61.2% for quartile 2, quartile 3, and quartile 4, respectively). Sex ratio (male:female) at d 62 was skewed toward more male fetuses following ET (61.1:38.9) compared with AI (43.2:56.8) and was consistent with the sex ratio among in vitro blastocysts (61.2:38.8). In conclusion, P/S was similar for AI and ET, although pregnancy loss between d 32 and 62 was greater for ET than for AI.


Assuntos
Lactação , Progesterona , Feminino , Masculino , Gravidez , Bovinos , Animais , Estações do Ano , Fertilidade , Transferência Embrionária/veterinária , Inseminação Artificial/veterinária
2.
J Dairy Sci ; 106(12): 9778-9792, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37641334

RESUMO

The aims of this study were (1) to evaluate potential associations between genetic traits, postpartum phenotypes, cow factors, and postpartum vaginal discharge score (VDS); and (2) to investigate possible associations between postpartum VDS, plasma progesterone (P4) after first service, and reproductive performance. First- and second-parity (n = 2,842) spring-calving lactating dairy cows from 35 dairy herds were enrolled. Farm visits were performed every 2 wk during the postpartum period and weekly during the breeding period. Cows that were at wk 3 and wk 7 postpartum and between 7 and 13 d after first artificial insemination (AI) were examined. Body condition score (BCS) was measured on all farm visits using a 1-to-5 scale (low ≤2.5; target ≥2.75). Transrectal ultrasound examinations were conducted to determine the presence or absence of a corpus luteum (CL). Vaginal discharge score was determined at wk 3 and wk 7 using a Metricheck device (Simcro) and a 1-to-4 scale (1 = clear mucus; 4 = mucopurulent with >50% purulent material ± odor). At wk 3, cows having a VDS ≤2 were considered to have normal reproductive tract health status (RTHS). At wk 7, cows having VDS = 1 were considered to have normal RTHS. Blood samples were collected at each visit, and plasma concentrations of glucose, ß-hydroxybutyrate, fatty acids, and progesterone (only during breeding visit) were analyzed. Animals with target BCS at wk 3 and wk 7 had greater odds of having normal RTHS at wk 3 and wk 7, respectively, than cows with low BCS. Cows with a CL at wk 3 and wk 7 had greater prevalence of normal RTHS at wk 3 and wk 7, respectively, compared with cows without a CL. Cows with normal RTHS had a lesser plasma concentration of ß-hydroxybutyrate at wk 3 and wk 7 and greater plasma concentration of glucose at wk 3 compared with animals with abnormal RTHS. More cows in the greatest quartiles for the fertility subindex of the Economic Breeding Index and genetic merit for milk production traits (milk kg and milk protein [%]) had normal RTHS at wk 3 and wk 7 compared with the other quartiles. Cows with VDS = 4 at wk 7 postpartum had lesser plasma P4 concentration after first AI (-1.2, -1.1, and -1.0 ng/mL compared with cows with VDS = 1, 2, and 3, respectively). Similarly, cows with VDS = 4 at both wk 3 and wk 7 had lesser pregnancy at first service, lesser cumulative pregnancy rates at wk 3, 6, and 12 during the breeding period, and longer interval from mating start date to conception (+3 d if VDS = 4 at wk 3; +5 d if VDS = 4 at wk 7), compared with cows having other VDS. In conclusion, cows with superior genetic merit for fertility traits and milk production traits, and favorable fertility phenotypes at wk 3 and wk 7, were all associated with greater likelihood of having normal RTHS. In turn, abnormal postpartum RTHS and greater postpartum VDS (score = 4) were associated with lesser odds of successful pregnancy establishment.


Assuntos
Doenças dos Bovinos , Descarga Vaginal , Gravidez , Feminino , Bovinos , Animais , Lactação/genética , Progesterona , Estações do Ano , Ácido 3-Hidroxibutírico , Período Pós-Parto , Fertilidade/genética , Descarga Vaginal/veterinária , Fenótipo , Glucose
3.
J Dairy Sci ; 106(11): 8133-8151, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37641353

RESUMO

The objective of this study was to characterize the species composition and functional potential of the vaginal and uterine microbiota at 1 wk postpartum in dairy cows diagnosed with or without purulent vaginal discharge (PVD) at 3 wk postpartum. The hypothesis was that differences in the vaginal and uterine microbiota between cows diagnosed with (PVD+) or without (PVD-) PVD were dependent on parity and breed. Cytobrush samples of the vagina and uterus were collected at 1 wk postpartum from 36 Holstein-Friesian (7 primiparous and 29 multiparous) and 29 Jersey (10 primiparous and 19 multiparous) cows. Microbial DNA was isolated from each sample and processed for shotgun metagenomic sequencing. The odds of multiparous cows being diagnosed as PVD+ was less compared with primiparous cows (OR = 0.21). Neither the α-diversity nor ß-diversity of the uterine and vaginal microbiota were associated with PVD but the ß-diversity was different between breeds and between parities. In the vagina of primiparous cows, differences in the microbiota of PVD- and PVD+ cows were minor, but the microbiota of multiparous PVD+ cows had greater relative abundance of Fusobacterium necrophorum, Trueperella pyogenes, Porphyromonas levii, and greater functional potential for amino acid and protein synthesis, energy metabolism, and growth compared with PVD- cows. The uterus of primiparous PVD+ cows had lesser relative abundance of Bacteroides heparinolyticus compared with PVD- cows. In the uterine microbiota, differences included greater functional potential for cellulose biosynthesis and fucose catabolism in multiparous PVD+ cows compared with PVD- cows. In the uterine microbiota of primiparous PVD+ cows, the functional potential for gram-negative cell wall synthesis and for negative regulation of tumor necrosis factor signaling was lesser compared with multiparous PVD+ cows. In the vagina of Holstein-Friesian PVD+ cows, the relative abundance of Caviibacter abscessus was greater whereas in the vagina of Jersey PVD+ cows the relative abundance of Catenibacterium mitsuokai, Finegoldia magna, Klebsiella variicola, and Streptococcus anginosus was greater compared with PVD- cows. In the uterine microbiota of Holstein-Friesian cows, the functional potential for spermidine biosynthesis was reduced compared with PVD- cows. In summary, differences in the species composition and functional potential of the vaginal and uterine microbiota between PVD- and PVD+ cows were dependent on parity and breed. The findings suggest that alternative strategies may be required to treat PVD for different parities and breeds of dairy cow.

4.
Support Care Cancer ; 29(3): 1337-1345, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32642951

RESUMO

BACKGROUND: Sydney Cancer Survivorship Centre (SCSC) clinic provides multidisciplinary care after primary adjuvant treatment, with ~ 40% of attendees continuing follow-up with SCSC. METHODS: SCSC survivors completed measures of symptoms, quality-of-life and lifestyle factors at initial visit (T1), first follow-up (T2) and 1 year (T3). Analyses used mixed effect models, adjusted for age, sex and tumour type. RESULTS: Data from 206 survivors (2013-2019) were included: 51% male; median age 63 years; tumour types colorectal 68%, breast 12%, upper gastrointestinal 12%, other 8%. Mean time from: T1 to T2, 3.6 months; T1 to T3, 11.8 months. Mean weight remained stable, but 45% (35/77) of overweight/obese survivors lost weight from T1 to T3. Moderately-intense aerobic exercise increased by 63 mins/week at T2, and 68 mins/week T3. Proportion meeting aerobic exercise guidelines increased from 20 to 41%. Resistance exercise increased by 26 mins/week at T2. Global quality-of-life was unchanged from T1 to T2, improving slightly by T3 (3.7-point increase), mainly in males. Mean distress scores were stable, but at T3 the proportion scoring 4+/10 had declined from 41 to 33%. At T3, improvements were seen in pain, fatigue and energy, but > 20% reported moderate-severe fatigue, pain or sleep disturbance. Proportion reporting 5+ moderate-severe symptoms declined from 35% at T1 to 26% at T3, remaining higher in women. CONCLUSIONS: Survivors attending SCSC increased exercise by 3 months, and sustained it at 1 year. Most overweight/obese survivors avoided further weight gain. Survivors had relatively good quality-of-life, with improvement in many symptoms and lifestyle factors at 1 year.


Assuntos
Sobreviventes de Câncer/psicologia , Qualidade de Vida/psicologia , Sobrevivência , Austrália , Institutos de Câncer , Feminino , Humanos , Estilo de Vida , Masculino , Pessoa de Meia-Idade , Fatores de Tempo
5.
J Dairy Sci ; 104(11): 11747-11758, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34419268

RESUMO

To maximize efficiency, profitability, and societal acceptance of modern dairy production, it is important to minimize the production of male dairy calves with poor beef merit. One solution involves using sex-sorted sperm (SS) to generate dairy replacements and breeding all other cows to an easy-calving, short-gestation bull with good beef merit. We used the Pasture Based Herd Dynamic Milk Model to investigate the effect of herd fertility and use of SS on farm net profit in a herd of 100 cows. This was completed by simulating herds with differing fertility performance (good, average, poor), and differing farm reproductive management [conventional semen (CONV) or SS with varying pregnancy per artificial insemination (P/AI) relative to CONV (i.e., relative P/AI 100%, 85%, and 70%)]. As an additional consideration, the method of allocating SS to cows was also examined. The first option used SS on random heifers and cows (S). The second option used SS on heifers and targeted high-fertility cows (SSel). The final option was similar to SSel, but used a fixed-time artificial insemination (AI) protocol to facilitate AI on the farm mating start date (SSync). For CONV, dairy breed semen was used for AI until 50 animals were pregnant (50% chance of a female calf), whereas for S, SSel, or SSync the target number of animals successfully conceiving with SS was set at 28 (based on assumed 90% chance of a female calf from pregnancies derived from SS). Beef breed semen was used on all other dams. The results indicated that the biggest effect on farm net profit was not based on whether or not SS was used, but instead was most affected by the overall fertility performance of the herd. Total farm profit decreased by 10% between the good and average fertility herds, and decreased by a further 12% between the average and poor fertility herds. In almost all situations, when the relative P/AI with SS was ≥85%, use of SS led to an overall increase of the farm net profit. There was an economic benefit of using either SSel or SSync compared with S for the average and poor fertility herds but not for the good fertility herd, highlighting an interaction between SS P/AI and overall herd fertility as well as management practices. If the relative P/AI with SS was <70%, the use of SS led to a decrease in profitability in all simulations except for SSync, highlighting the importance of a good management strategy for use of SS. The findings in this study indicated that SS has significant potential to help facilitate greater integration between the dairy and beef production sectors, as well as increase farm profitability when used appropriately.


Assuntos
Inseminação Artificial , Pré-Seleção do Sexo , Animais , Bovinos , Indústria de Laticínios , Feminino , Fertilidade , Inseminação Artificial/veterinária , Masculino , Gravidez , Estações do Ano , Sêmen , Pré-Seleção do Sexo/veterinária , Espermatozoides
6.
J Dairy Sci ; 104(12): 12968-12979, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34482975

RESUMO

The aims of this study were to (1) evaluate postpartum phenotypes, cow factors, and genetic traits associated with plasma progesterone (P4) concentrations after first artificial insemination (AI); (2) determine variation in daily plasma P4 concentrations between d 7 and 13 after first AI; and (3) evaluate associations between plasma P4 concentrations and pregnancy success after first AI. First and second parity (n = 2,797) spring-calving lactating dairy cows from 35 dairy herds were enrolled. Farm visits were performed every 2 wk during the postpartum period as follows: cows that were at wk 3 (range: 14-27 d in milk) and wk 7 (range: 42-55 d in milk) postpartum were examined. Farm visits were performed weekly during the breeding season, and cows that were between 7 and 13 d after the first AI were examined. Body condition score (BCS) was measured at each visit using a 1 to 5 scale [low (≤2.75), target (≥3.0)]. Transrectal ultrasound examinations were conducted at wk 3 and wk 7 postpartum visits to determine presence or absence of a corpus luteum (CL) and uterine tract score [scale of G1 (best)-G4 (worst)]. Blood samples were collected at each visit, and plasma concentrations of glucose, ß-hydroxybutyrate, and fatty acids were analyzed. On the day of the weekly farm visit during the breeding season, blood samples for P4 determination were collected from all cows that were between 7 and 13 d after first AI during the breeding period. Cows that had a CL present and a G1 uterine score at wk 7 postpartum had greater plasma P4 concentration after first AI (+0.67 ng/mL and +0.4 ng/mL, respectively) compared with cows with no CL present and with a uterine score ≥G3. Cows with low BCS at wk 7 postpartum had lesser plasma P4 concentration after first AI than cows with target BCS. Each unit increase in plasma fatty acids and ß-hydroxybutyrate concentration at AI was associated with 0.45 ± 0.33 ng/mL (estimate ± standard error) and 0.07 ± 0.04 ng/mL greater plasma P4 concentration after first AI, respectively. Regarding genetic merit traits, each unit increase in fertility subindex was associated with 0.005 ± 0.003 ng/mL greater P4 concentration. In addition, for every 1 ng/mL increase in plasma P4 concentration, the odds of estimated probability of pregnancy per AI increased by 3% (odds ratio = 1.03; 95% confidence interval = 1.00, 1.05). In conclusion, cows with superior genetic merit for fertility traits and milk production traits, favorable fertility phenotypes at wk 7 postpartum, (e.g., presence of a CL, a G1 uterine score, and target BCS), and blood parameters indicative of better metabolic status at AI were all associated with greater plasma P4 concentration after AI. In turn, greater plasma P4 concentrations were associated with greater odds of successful pregnancy establishment. This study underlines the important associations between early postpartum fertility phenotypes (CL presence, uterine health status) and subsequent plasma P4 concentrations after first AI, and hence provides additional evidence of the mechanisms through which selection for fertility traits improves phenotypic fertility performance.


Assuntos
Lactação , Progesterona , Animais , Bovinos/genética , Feminino , Inseminação Artificial/veterinária , Fenótipo , Período Pós-Parto , Gravidez , Probabilidade , Estações do Ano
7.
N Z Vet J ; 69(1): 27-37, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32781918

RESUMO

Aims: To describe the current practices and preferences of New Zealand veterinarians towards continuing professional development (CPD), explore factors acting as perceived barriers to CPD engagement, and identify opportunities for reforming the current CPD regulations. Methods: A cross-sectional survey of all veterinarians registered with the Veterinary Council of New Zealand (VCNZ) was conducted in October 2019. Descriptive statistics were provided for all quantitative study variables and thematic analysis was performed on the free-text survey comments to identify key issues regarding the current CPD regulations in New Zealand. Results: Complete survey responses were provided by 222/3,484 (6.4%) registered veterinarians. Most respondents (153/222; 68.9%) were satisfied with the amount of CPD completed and spent a mean of $2,511 (median $2,000; min $0; max $20,000) on CPD activities each year. The most popular CPD formats were those involving collegial interaction including conference and skills training workshops. The choice of CPD activities was most commonly influenced by interest in the topics and the desire to become more competent in their work while the main barriers were difficulties fitting CPD around work and family commitments. There were 164 (73.9%) respondents who cited at least one occasion in the previous 12 months where participating in CPD caused them to modify their existing practices. Thematic analysis of the free-text comments revealed several major themes related to the administrative burden of recording CPD activities under the current regulatory framework, and the need to develop CPD plans tailored towards the unique circumstances and goals of individual veterinarians. Respondents also expressed concerns over the reliability of using CPD record audits for evaluating professional competency. Factors identified as being the most helpful for improving the current CPD framework were simplifying the CPD points categories and developing a mechanism to record and share CPD activities in real-time. Conclusions: While most respondents felt there was significant value in completing CPD, the current regulatory framework was perceived to be administratively burdensome and inflexible in allowing them to tailor CPD activities to match their unique employment situation, learning style and professional goals. Clinical relevance: Providing resources that could assist veterinarians to design and implement tailored CPD programmes may improve professional and personal outcomes. However, further research is needed to develop more effective mechanisms for identifying veterinarians who are not performing competently without placing excessive administrative burdens on those who are.


Assuntos
Atitude do Pessoal de Saúde , Educação Continuada , Médicos Veterinários/psicologia , Animais , Competência Clínica , Estudos Transversais , Humanos , Nova Zelândia , Inquéritos e Questionários
8.
N Z Vet J ; 69(1): 38-50, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32814498

RESUMO

Aims: To describe the experiences of employers, work colleagues, and mentors who have recently worked with new veterinary graduates in New Zealand, explore factors influencing perceptions of new graduate performance, and identify opportunities for providing better support to new graduates and their employers. Methods: All veterinarians registered with the Veterinary Council of New Zealand (VCNZ) were invited to participate in a cross-sectional survey. Descriptive statistics were calculated for all study variables and a mixed-effects multivariable logistic regression model was constructed to explore factors associated with perceptions of new graduate performance. Thematic analysis was performed on free-text comments to identify key issues with new graduate support. Results: The survey was completed by 83 veterinarians with 68 (81.9%) providing information on 95 individual new graduates they had mentored. New graduates exceeded expectations in their ability to research cases and communicate with colleagues while time management and awareness of financial issues were highlighted as weaknesses. The mean total time respondents spent supervising new graduates during their first year was 166.8 (median 95; min 0; max 852) hours. New graduates who were not considered the best applicants for the job and those who had left their job were 6.3 (95% CI = 2.11-11.8) and 5.4 (95% CI = 1.55-19.0) times, respectively, more likely to be rated as performing below expectations. Thematic analysis revealed major themes related to the inadequate preparation of students in veterinary school, employers lacking adequate training and resources to supervise new graduates, and intergenerational differences in work ethic and expectations, which may be contributing to burnout and dissatisfaction for new graduates and their employers. Components of new graduate support programmes that were perceived to be most helpful were having regular meetings between the supervisor and employee to discuss performance and wellbeing, having compulsory sessions with an experienced veterinarian for career advice, and having non-compulsory checklists of technical and non-technical skills to guide professional development planning. However, there was varying levels of support for including these measures in a formal new graduate support programme. Conclusions: While respondents highlighted many challenges faced by new graduates and their employers, there was often disagreement about the root cause of the problem and potential solutions. Clinical relevance: Providing non-compulsory checklists to help employers work with new graduates to develop tailored professional development plans and support structures within their unique practice environment may result in more positive experiences as new graduates transition from student to independent practitioner.


Assuntos
Atitude do Pessoal de Saúde , Competência Clínica , Relações Interprofissionais , Mentores/psicologia , Médicos Veterinários/psicologia , Adulto , Animais , Educação em Veterinária , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Nova Zelândia , Faculdades de Medicina Veterinária , Inquéritos e Questionários
9.
Diabet Med ; 37(6): 1049-1057, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32125000

RESUMO

AIMS: To examine the association of HbA1c and glucose levels with incident diabetic retinopathy according to black African or white European ancestry. METHODS: In this retrospective cohort study of 202 500 US Veterans with diabetes (2000-2014), measures included HbA1c , outpatient random serum/plasma glucose, and incident retinopathy [conversion from negative to ≥2 positive evaluations (ICD-9 codes), without a subsequent negative]. RESULTS: At baseline, the study population had a mean age of 59.3 years, their mean BMI was 31.9 kg/m2 , HbA1c level was 57 mmol/mol (7.4%) and glucose level was 8.8 mmol/l, and 77% were of white European ancestry (white individuals) and 21% of black African ancestry (black individuals). HbA1c was 0.3% higher in black vs white individuals (P < 0.001), adjusting for baseline age, sex, BMI, estimated glomerular filtration rate (eGFR), haemoglobin, and average systolic blood pressure and glucose. Over 11 years, incident retinopathy occurred in 9% of black and 7% of white individuals, but black individuals had higher HbA1c , glucose, and systolic blood pressure (all P < 0.001); adjusted for these factors, incident retinopathy was reduced in black vs white individuals (P < 0.001). The population incidence of retinopathy (7%) was associated with higher mean baseline HbA1c in individuals with black vs white ancestry [63 mmol/mol (7.9%) vs 58 mmol/mol (7.5%); P < 0.001)], but with similar baseline glucose levels (9.0 vs 9.0 mmol/l; P = 0.660, all adjusted for baseline age, sex and BMI). CONCLUSIONS: Since retinopathy occurs at higher HbA1c levels in black people for a given level of average plasma glucose, strategies may be needed to individualize the interpretation of HbA1c measurements.


Assuntos
Negro ou Afro-Americano , Diabetes Mellitus/metabolismo , Retinopatia Diabética/etnologia , Hemoglobinas Glicadas/metabolismo , População Branca , Idoso , População Negra , Glicemia , Retinopatia Diabética/epidemiologia , Retinopatia Diabética/etiologia , Retinopatia Diabética/metabolismo , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Estados Unidos/epidemiologia , United States Department of Veterans Affairs
10.
J Dairy Sci ; 103(8): 7509-7520, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32505400

RESUMO

The objective of this retrospective study was to compare survival during the first year of life and adult performance of offspring derived from artificial insemination (AI) with X-sorted or conventional sperm processed from the same ejaculates. We analyzed a data set that included AI of dairy heifers and lactating cows with fresh conventional sperm (3 × 106 sperm per straw), fresh X-sorted sperm (1 or 2 × 106 sperm per straw), or frozen X-sorted sperm (2 × 106 sperm per straw). The data set contained records of 5,179 offspring born on 396 farms. Offspring were classified as born from conventional sperm (CONV) if they were the product of an insemination with fresh conventional sperm, or born from X-sorted sperm (SS) if they were product of any of the 3 X-sorted sperm treatments. Generalized linear mixed models were used to evaluate the effect of sperm treatment on (1) survival during the first year of life; (2) reproductive performance, lactation performance, and survival of female offspring; and (3) slaughter characteristics of male offspring. Stillbirth rates and mortality rates during the first 2 mo of life were greater for male calves (2.8 and 5.0%, respectively) than for female calves (1.6 and 2.0%, respectively). No differences between offspring derived from SS and CONV were detected for incidences of stillbirth or mortality during the first 12 mo of life within sex of calf. Reproductive performance, milk volume, milk fat, milk protein yields during first; second; and third lactations, and survival to third lactation did not differ between female offspring derived from CONV and SS. Across all age groups, CONV steers had heavier carcasses than SS steers (325.3 vs. 318.3 kg), but there were no differences in weight between CONV and SS steers within any of the age groups (≤24, 25-27, 28-30, and >30 mo of age). The distribution of slaughter age did not differ between CONV and SS steers when the analysis was restricted to herds that reared steers derived from both types of sperm. Carcass conformation and fat scores of steers were not affected by sperm treatment. There was no difference in carcass weight between young bulls (≤2 yr) derived from CONV or SS. In conclusion, the results provide no evidence of differences in survival during the first year of life between offspring derived from CONV or SS, or for any of the reproductive and lactation performance characteristics studied between female offspring derived from CONV or SS. Modest differences in carcass weight between CONV and SS steers were detected, but this may reflect differences in management and husbandry in the rearing herds rather than the sex-sorting process. A controlled study using steers derived from conventional or X-sorted sperm from split ejaculates and reared under the same husbandry conditions is needed to clarify whether there is a true difference in body weight gain due to the sex-sorting process.


Assuntos
Bovinos , Inseminação Artificial/veterinária , Sêmen , Espermatozoides , Cromossomo X , Animais , Animais Recém-Nascidos , Feminino , Congelamento , Inseminação Artificial/métodos , Lactação , Modelos Lineares , Masculino , Leite , Proteínas do Leite , Mortalidade , Gravidez , Estudos Retrospectivos , Espermatozoides/citologia
11.
J Dairy Sci ; 103(1): 929-939, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31668438

RESUMO

The objective was to evaluate the reproductive performance of frozen sex-sorted sperm at 4 × 106 sperm per dose (SexedULTRA 4M, Sexing Technologies, Navasota, TX) relative to frozen conventional sperm in seasonal-calving pasture-based dairy cows. Semen from Holstein-Friesian (n = 8) and Jersey (n = 2) bulls was used. Four of the Holstein bulls used were resident at or near a sex-sorting laboratory (Cogent, UK, or ST Benelux, the Netherlands). The remaining 6 bulls were located at studs in Ireland. For these 6 bulls, ejaculates were collected, diluted with transport medium, and couriered to Cogent in parcel shippers. Transit time from ejaculation to arrival at the sorting laboratory was 6 to 7 h. For all bulls, ejaculates were split and processed to provide frozen conventional sperm (CONV) at 15 × 106 sperm per straw and frozen sex-sorted (SS) sperm at 4 × 106 sperm per straw and used to inseminate lactating dairy cows after spontaneous estrus. Pregnancy diagnosis was performed by ultrasound scanning (n = 7,246 records available for analysis). Generalized linear mixed models were used to examine effects on pregnancy per AI (P/AI) at first artificial insemination, with sperm treatment (CONV vs. SS), bull (n = 10), and treatment × bull interaction as the fixed effects, and herd (n = 142) as a random effect. Overall, P/AI was greater for cows inseminated with CONV than for those inseminated with SS (59.9% vs. 45.5%; 76.0% relative to CONV). This study was not designed to compare resident bulls vs. shipped ejaculates, but the magnitude of the difference between P/AI achieved by CONV and SS was apparently less for resident bulls (60.3% vs. 50.2%) than for shipped ejaculates (58.6% vs. 40.7%). We discovered a treatment × bull interaction for shipped ejaculates (P/AI ranged from 45 to 86% relative to CONV) but not for the resident bulls (P/AI ranged from 81 to 87% relative to CONV). Relative P/AI of SS compared with CONV was greater in cows with high or average fertility potential (76.1% and 78.3%, respectively) than in cows with low fertility potential (58.1%). In 33.1% of the enrolled herds, the P/AI achieved with SS was 90% or more of the P/AI achieved with CONV; this was mainly explained by herds in which SS performed exceptionally well but CONV performed poorly. In conclusion, SS had lower overall P/AI compared with CONV; however, P/AI achieved with SS was dependent on the bull, fertility potential of the cow, and herd. Strategies to improve the P/AI with SS in seasonal-calving pasture-based lactating dairy cows require further research.


Assuntos
Bovinos/fisiologia , Inseminação Artificial/veterinária , Lactação/fisiologia , Preservação do Sêmen/veterinária , Pré-Seleção do Sexo/veterinária , Criação de Animais Domésticos , Animais , Feminino , Fertilidade , Congelamento , Inseminação Artificial/métodos , Masculino , Gravidez , Estações do Ano , Sêmen , Espermatozoides
12.
J Dairy Sci ; 103(1): 1002-1015, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31677840

RESUMO

The objective of this study was to evaluate the associations between corpus luteum (CL) status, uterine health, body condition score (BCS), metabolic status, and parity at wk 3 and 7 postpartum in seasonal-calving, pasture-based, lactating dairy cows. The associations between those phenotypes and individual genetic traits were also evaluated. First- and second-parity spring-calving lactating dairy cows (n = 2,600) from 35 dairy farms in Ireland were enrolled. Farms were visited every 2 weeks; cows that were at wk 3 (range 14 to 27 DIM) and wk 7 (range 42 to 55 DIM) postpartum were examined. Body condition score was measured using a scale of 1 to 5 with 0.25 increments. Transrectal ultrasound examination was performed at wk 3 and 7 postpartum to determine presence or absence of CL and ultrasound reproductive tract score. Blood samples were collected at each visit and the concentrations of glucose, ß-hydroxybutyrate (BHB), and fatty acids (FA) were analyzed by using enzymatic colorimetry. Cows were grouped into 3 BCS categories [low (≤2.5), target (≥2.75 and ≤3.25), and high (≥3.5)]; 2 CL status categories: (present or absent); 2 uterine health status (UHS) categories (normal and abnormal); and 3 metabolic status categories [good (high glucose, low fatty acids and BHB), poor (low glucose, high fatty acids and BHB), and moderate (all other combinations)]. Fisher's exact test was used to test associations between variables and was supplemented by logistic regression. We found associations between UHS (wk 3 and 7), BCS (wk 3 and 7), parity (wk 3 and 7) metabolic status (wk 3), and predicted transmitting ability for calving interval (PTA for CIV; wk 3) and CL status. Cows that had abnormal UHS, low BCS, primiparity, and poor metabolic status, and were in the quartile with the greatest PTA for CIV were less likely to have had CL present at wk 3 and 7 postpartum. We also found associations between CL status (wk 3 and 7), BCS (wk 3 and 7), parity (wk 3 and 7), and PTA for CIV (wk 3) and UHS. Cows that did not have a CL present had low BCS, primiparity, and that were in the quartile with greatest PTA for CIV, had a greater risk of abnormal UHS at wk 3 and 7 postpartum. We observed strong associations between CL status, UHS, BCS, metabolic status, parity, and individual genetic traits at wk 3 and 7 postpartum in seasonal-calving, pasture-based lactating dairy cows. Achieving target BCS and good metabolic status, and selecting cows based on PTA for CIV, are all expected to increase the likelihood of hastening the resumption of estrous cyclicity and enhancing uterine health during the postpartum period.


Assuntos
Bovinos/genética , Fertilidade/genética , Lactação/fisiologia , Criação de Animais Domésticos , Animais , Bovinos/fisiologia , Feminino , Irlanda , Lactação/genética , Leite/metabolismo , Paridade , Período Pós-Parto , Gravidez , Estações do Ano
13.
J Dairy Sci ; 103(1): 1016-1030, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31759601

RESUMO

The objective of this study was to evaluate associations between corpus luteum (CL) status, uterine health, body condition score (BCS), metabolic status, parity, genetic merit for fertility traits, and reproductive performance in pasture-based dairy cows managed for seasonal reproduction. First- and second-lactation (n = 2,600) spring-calving dairy cows from 35 dairy farms located in Ireland were enrolled in the study. Farms were visited every 2 wk, and animals that were at wk 3 (range: 14-27 d in milk) and wk 7 (range: 42-55 d in milk) postpartum were examined. Body condition score was measured using a 1-to-5 scale in 0.25-point increments. Transrectal ultrasound examination was performed at wk 3 and 7 postpartum to determine presence or absence of CL and ultrasound reproductive tract score (scale of G1-G4). Blood samples were collected at each visit, and the concentrations of glucose, ß-hydroxybutyrate (BHB), and fatty acids (FA) were analyzed using enzymatic colorimetry. Animals were grouped into 3 BCS categories [low (≤2.5), target (2.75-3.25), and high (≥3.5)], 2 CL categories (present or absent), 2 uterine health status categories (normal or abnormal), and 3 metabolic status categories [good (high glucose, low FA and BHB), poor (low glucose, high FA and BHB), and moderate (all other combinations)]. Fisher's exact test was used to test for associations between variables and was supplemented by logistic regression. More cows with a CL at wk 7 were served during the first 21 d of the breeding period compared with cows without a CL. Cows classified as having a uterine score of G3 or G4 at wk 3 and 7 had lower odds of pregnancy establishment during the breeding period compared with animals with a uterine score of G1 or G2. Animals with low BCS at wk 7 had lower odds of pregnancy establishment than cows with a target BCS. Cows classified as having good metabolic status at both wk 3 and wk 7 had greater odds of pregnancy establishment during the first 21 d of the breeding season than those classified as having poor metabolic status. Overall, primiparous cows had greater reproductive performance than second-parity cows. Animals in the quartiles with the best predicted transmitting ability for survival and calving interval had better reproductive performance compared with animals in the other quartiles. Cows that had better genetic merit for fertility traits and good metabolic status, achieved target BCS, and had a favorable ultrasound reproductive tract score and a CL present at wk 7 postpartum had superior reproductive performance.


Assuntos
Bovinos/genética , Lactação/genética , Período Pós-Parto , Criação de Animais Domésticos , Animais , Bovinos/fisiologia , Suplementos Nutricionais , Feminino , Fertilidade/genética , Irlanda , Lactação/fisiologia , Leite/metabolismo , Gravidez , Reprodução/genética , Estações do Ano
14.
J Dairy Sci ; 103(2): 1685-1700, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31837792

RESUMO

The objective of the current study was to examine phenotypic fertility performance and survival, and to gain insight into underlying factors that may contribute to greater fertility performance in 2 divergent genetic groups (GG) of Holstein-Friesian, selected using the Irish Economic Breeding Index (EBI). The GG were evaluated across 3 spring calving pasture-based feeding treatments (FT) over 4 yr. The 2 divergent GG were (1) high EBI; representative of the top 5% nationally (elite), and (2) EBI representative of the national average (NA). In each year, 90 elite and 45 NA cows were randomly allocated to 1 of 3 FT: control, lower grass allowance, and high concentrate. No interaction between GG and FT was observed for any of the measures of fertility investigated. The elite cows achieved significantly greater pregnancy rate to first service (+14.9 percentage points), and significantly greater pregnancy rates after 21, 42, and 84 d of breeding (+17.3, +15.2, and +9.6 percentage points, respectively) compared with NA. The number of services per cow was fewer for elite (1.57) compared with NA (1.80). The interval from mating start date to pregnancy was significantly shorter for elite cows compared with NA. The elite cows maintained greater mean body condition score than NA throughout the study (2.91 vs. 2.72), and had greater body condition score at calving, artificial insemination, and drying off compared with NA. The elite cows had greater mean circulating concentrations of insulin-like growth factor-1 compared with NA. No significant effect was observed of GG on commencement of luteal activity, or progesterone profile variables. Greater survival to the start of fifth lactation was observed for elite cows. The elite cows were 43% less likely to be culled than NA by the beginning of the fifth lactation. The results highlight the success of the Economic Breeding Index to deliver reproductive performance and longevity consistent with industry targets across a range of seasonal pasture-based FT. The results also clearly demonstrate the potential of appropriate genetic selection to reverse negative fertility trends incurred during previous decades of selection for milk production alone.


Assuntos
Bovinos/fisiologia , Indústria de Laticínios , Dieta/veterinária , Fertilidade , Animais , Cruzamento , Bovinos/genética , Bovinos/crescimento & desenvolvimento , Indústria de Laticínios/métodos , Feminino , Fertilidade/genética , Inseminação Artificial/veterinária , Lactação , Leite , Poaceae , Gravidez , Progesterona , Reprodução/genética , Estações do Ano
15.
J Dairy Sci ; 103(12): 12059-12068, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33069411

RESUMO

The objective was to use ovulation synchronization with timed artificial insemination (TAI) to evaluate the effect of timing of artificial insemination (AI) with frozen sex-sorted sperm on fertility performance in pasture-based compact calving herds. Ejaculates from 3 Holstein-Friesian bulls were split and processed to provide frozen sex-sorted sperm (SS) at 4 × 106 sperm per straw, and frozen conventional sperm at 15 × 106 sperm per straw (CONV). A modified Progesterone-Ovsynch protocol was used for estrous synchronization, with TAI occurring 16 h after the second GnRH injection for cows assigned to CONV, and either 16 h (SS-16) or 22 h (SS-22) for cows assigned to SS. Pregnancy diagnosis was conducted by transrectal ultrasound scanning of the uterus 35 to 40 d after TAI (n = 2,175 records available for analysis). Generalized linear mixed models were used to examine the effects of treatment on pregnancy per artificial insemination (P/AI). Fixed effects included treatment (n = 3), bull (n = 3), treatment by bull interaction, parity (n = 4), days-in-milk category (n = 3), and treatment by days-in-milk category, with herd (n = 24) included as a random effect. Pregnancy per AI was greater for CONV compared with both SS-16 and SS-22 (61.1%, 49.0%, and 51.3%, respectively), and the SS treatments did not differ from each other (relative P/AI for SS-16 and SS-22 vs. CONV were 80.2% and 84.0%, respectively). There were significant bull and treatment by bull interaction effects. Additional analysis was undertaken using a model that included herd as a fixed effect. This analysis identified marked herd-to-herd variation (within-herd relative P/AI for the combined SS treatments vs. CONV ranged from 48-121%). The tertile of herds with the best performance achieved a mean relative P/AI of 100% (range = 91-121%), indicating that P/AI equivalent to CONV is achievable with SS. Conversely, the tertile of herds with the poorest performance achieved a mean relative P/AI of 67% (range = 48-77%). We found that SS resulted in poorer overall P/AI compared with CONV sperm regardless of timing of AI. Marked variation existed between herds; however, one-third of herds achieved P/AI results equal to CONV. Identification of factors responsible for the large herd-to-herd variation in P/AI with SS, and development of strategies to reduce this variation, warrant further research.


Assuntos
Bovinos/fisiologia , Inseminação Artificial/veterinária , Lactação , Ovulação , Estações do Ano , Espermatozoides , Animais , Estro/efeitos dos fármacos , Sincronização do Estro/métodos , Feminino , Fertilidade/efeitos dos fármacos , Congelamento , Hormônio Liberador de Gonadotropina/farmacologia , Lactação/efeitos dos fármacos , Modelos Lineares , Masculino , Leite , Ovulação/efeitos dos fármacos , Paridade , Gravidez , Progesterona/farmacologia , Processos de Determinação Sexual , Espermatozoides/efeitos dos fármacos , Fatores de Tempo
16.
N Z Vet J ; 68(4): 214-224, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32151233

RESUMO

Aims: To explore the experiences of recent veterinary graduates in their first employment position, to investigate risk factors for leaving this position, and to identify their preferences towards new graduate support programmes.Methods: All 693 individuals who completed their veterinary degree and registered with the Veterinary Council of New Zealand between May 2014 and May 2019 were invited to participate in a cross-sectional survey regarding their employment experiences. Descriptive statistics were calculated for all study variables and a multivariable logistic regression model was constructed to explore factors associated with increased risk of new graduates leaving their first position. Thematic analysis was performed on the free-text comments to identify key issues with new graduate support.Results: The survey was completed by 162/693 veterinarians (23.4%). Of 153 respondents who provided information on their first employment position, 61 (39.9%) commenced their veterinary career in companion animal practice, 44 (28.8%) in mixed animal practice, 36 (23.5%) in large animal practice, and 12 (7.8%) worked in another veterinary discipline. Most respondents (124/153; 81.0%) were rostered for after-hours emergency shifts during their first year with variable levels of support from their practice. Among 72 respondents (44.4%) who had left their first job, the mean length of employment was 1.4 (median 1; min 1; max 4) years. The most common reasons reported for leaving were a toxic practice culture and lack of adequate support. The risk of leaving was increased by being put in situations they could not handle (OR 5.26; 95% CI = 1.49-20.6) and employers that did not regularly check their wellbeing (OR 5.08; 95% CI = 1.52-18.9). Only 56/144 (38.9%) respondents and 30/144 (20.8%) respondents supported introducing compulsory checklists of technical and soft skills, respectively. Providing regular feedback, creating a supportive practice culture, setting reasonable workload expectations, providing clinical and professional advice, and developing tailored skills development plans were identified as key areas that employers of new graduates should address.Conclusions: Lack of appropriate mentoring and toxic practice cultures were the most common reasons for new graduates leaving their first job. Although respondents identified that employers should provide new graduates with better support, most were not supportive of introducing a compulsory programme.Clinical relevance: To help new graduates transition into their first professional veterinary roles, employers should ensure that new graduates are only placed in situations that they can handle competently and check regularly on their mental and physical wellbeing.


Assuntos
Emprego , Satisfação no Emprego , Médicos Veterinários , Coleta de Dados , Feminino , Humanos , Masculino , Nova Zelândia
17.
Opt Express ; 27(8): 11312-11322, 2019 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-31052977

RESUMO

We demonstrate frequency modulation (FM) in an external cavity (EC) III-V/silicon laser, comprising a reflective semiconductor optical amplifier (RSOA) and a silicon nitride (SiN) waveguide vertically coupled to a 2D silicon photonic crystal (PhC) cavity. The PhC cavity acts as a tunable narrowband reflector giving wavelength selectivity. The FM was achieved by thermo-optical modulation of the reflector via a p-n junction. Single-mode operation was ensured by the short cavity length, overlapping only one longitudinal laser mode with the reflector. We investigate the effect of reflector modulation theoretically and experimentally and predict a substantial tracking of the resonator by the laser frequency with very small intensity modulation (IM).

18.
Support Care Cancer ; 27(10): 3739-3747, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30710242

RESUMO

PURPOSE: Cancer survivors experience significant health concerns compared to the general population. Sydney Survivorship Clinic (SSC) is a multi-disciplinary clinic aiming to help survivors treated with curative intent manage side effects, and establish a healthy lifestyle. Here, we determine the health concerns of survivors post-primary treatment. METHODS: Survivors completed questionnaires assessing symptoms, quality of life (QOL), distress, diet, and exercise before attending SSC, and a satisfaction survey after. Body mass index (BMI), clinical findings and recommendations were reviewed. Descriptive statistical methods were used. RESULTS: Overall, 410 new patients attended SSC between September 2013 and April 2018, with 385 survivors included in analysis: median age 57 years (range 18-86); 69% female; 43% breast, 31% colorectal and 19% haematological cancers. Median time from diagnosis, 12 months. Common symptoms of at least moderate severity: fatigue (45%), insomnia (37%), pain (34%), anxiety (31%) and with 56% having > 5 moderate-severe symptoms. Overall, 45% scored distress ≥ 4/10 and 62% were rated by clinical psychologist as having 'fear of cancer recurrence'. Compared to population mean of 50, mean global QOL T-score was 47.2, with physical and emotional well-being domains most affected. Average BMI was 28.2 kg/m2 (range 17.0-59.1); 61% overweight/obese. Only 31% met aerobic exercise guidelines. Overall, 98% 'agreed'/'completely agreed' attending the SSC was worthwhile, and 99% would recommend it to others. CONCLUSION: Distress, fear of cancer recurrence, fatigue, obesity and sedentary lifestyle are common in cancer survivors attending SSC and may best be addressed in a multi-disciplinary Survivorship Clinic to minimise longer-term effects. This model is well-rated by survivors.


Assuntos
Ansiedade/psicologia , Sobreviventes de Câncer/psicologia , Neoplasias/psicologia , Sistemas de Apoio Psicossocial , Qualidade de Vida/psicologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Exercício Físico , Fadiga/psicologia , Medo/psicologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/patologia , Recidiva Local de Neoplasia/psicologia , Neoplasias/terapia , Dor , Comportamento Sedentário , Distúrbios do Início e da Manutenção do Sono , Inquéritos e Questionários , Adulto Jovem
19.
J Dairy Sci ; 102(5): 4651-4661, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30852009

RESUMO

The hypothesis of this study was that cows with good genetic merit for fertility traits (Fert+) would produce oocytes and embryos of greater quality than cows with poor genetic merit for fertility traits (Fert-) and that mRNA expression of candidate genes would reflect the observed differences in quality. The aim of the study, therefore, was to determine the effect of genetic merit for fertility traits on morphological classification and mRNA abundance of key genes in immature oocytes and cumulus cells following ovum pick-up and in embryos following superovulation, artificial insemination (AI), and uterine flushing. In experiment 1, 17 Fert+ and 11 Fert- cows, ranging from 54 to 84 d in milk, were submitted to ovum pick-up on 4 occasions during a 2-wk period. Recovered cumulus-oocyte complexes (COC) were morphologically graded. Oocytes and cumulus cells were separated, and mRNA abundance of genes associated with oocyte developmental competence was measured. There was no effect of genotype on the distribution of COC grades or on the mRNA abundance of the candidate genes in grade 1 COC. In experiment 2, 20 Fert+ and 19 Fert- cows, ranging from 71 to 189 d in milk, were submitted to superovulation and AI. The uteri of cows that responded to the superovulation protocol (17 Fert+ and 16 Fert- cows) were nonsurgically flushed 7 d postovulation. Recovered embryos were morphologically graded, and mRNA abundance of genes associated with embryo development was measured in grade 1 blastocysts. The response to the superovulation protocol was assessed by counting the number of codominant follicles on the day of AI, which was similar for both genotypes (22.0 ± 9.7 and 19.8 ± 8.2 for Fert+ and Fert- cows, respectively). There was no effect of genotype on the proportion of transferable embryos recovered or on the mRNA abundance of the candidate genes tested in the grade 1 blastocysts. Of the total embryos classified as blastocysts, however, the Fert+ cows tended to have a greater proportion of grade 1 blastocysts compared with Fert- cows (90% vs. 64%, respectively). In conclusion, genetic merit for fertility traits had a no effect on mRNA abundance of the candidate genes that were examined in immature oocytes and cumulus cells and in embryos recovered after superovulation. The observed differences in morphological blastocyst quality following superovulation would suggest that the superior reproductive performance of Fert+ cows could arise during the later stages of embryo development from d 7 until maternal recognition of pregnancy.


Assuntos
Bovinos/genética , Desenvolvimento Embrionário/genética , Fertilidade/genética , Leite/metabolismo , Reprodução/genética , Animais , Blastocisto/fisiologia , Bovinos/embriologia , Bovinos/fisiologia , Transferência Embrionária/veterinária , Feminino , Genótipo , Inseminação Artificial/veterinária , Lactação , Recuperação de Oócitos/veterinária , Oócitos/fisiologia , Fenótipo , Gravidez , Superovulação , Útero/fisiologia
20.
J Dairy Sci ; 102(11): 10530-10542, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31447149

RESUMO

Our objective in this study was to evaluate the reproductive performance of dairy heifers and cows inseminated with fresh or frozen sex-sorted semen (SS) in seasonal-calving pasture-based dairy herds. Ejaculates of 10 Holstein-Friesian bulls were split and processed to provide (1) fresh conventional semen at 3 × 106 sperm per straw (CONV); (2) fresh SS at 1 × 106 sperm per straw (SS-1M); (3) fresh SS semen at 2 × 106 sperm per straw (SS-2M); and (4) frozen SS at 2 × 106 sperm per straw (SS-FRZ). Generalized linear mixed models were used to evaluate the effect of semen treatment and other explanatory variables on pregnancy per artificial insemination (P/AI) in heifers (n = 3,214) and lactating cows (n = 5,457). In heifers, P/AI was greater for inseminations with CONV (60.9%) than with SS-FRZ (52.8%) but did not differ from SS-1M (54.2%) or SS-2M (53.5%). Cows inseminated with CONV had greater P/AI (48.0%) than cows inseminated with SS, irrespective of treatment (SS-1M, SS-2M, and S-FROZEN; 37.6, 38.9, and 40.6%, respectively). None of the SS treatments differed from each other with regard to P/AI in either heifers or cows. The relative performance of SS compared with CONV was also examined [i.e., relative P/AI = (SS P/AI)/(CONV P/AI) × 100]. Frozen SS achieved relative P/AI >84%. Bull affected P/AI in both heifers and cows, but no bull by semen treatment interaction was observed. In heifers, P/AI increased with increasing predicted transmitting ability for milk protein percentage. In cows, P/AI increased with increasing Economic Breeding Index (EBI) and with days in milk (DIM) at AI but decreased with increasing EBI milk subindex, parity and with DIM2. Cows in parity ≥5 had the lowest P/AI and differed from cows in parities 1, 2, or 3. Dispatch-to-AI interval of fresh semen did not affect P/AI in lactating cows, but a dispatch-to-AI interval by bull interaction was detected whereby P/AI was constant for most bulls but increased with greater dispatch-to-AI intervals for 2 bulls. In conclusion, frozen SS achieved greater P/AI relative to conventional semen than was previously reported in lactating cows. Fresh SS did not achieve greater P/AI than frozen SS, regardless of whether the sperm dose per straw was 1 × 106 or 2 × 106. A bull effect for all semen treatments, as well as a dispatch-to-AI interval by bull interaction for fresh semen, highlights the importance of using a large team of bulls for breeding management.


Assuntos
Bovinos/fisiologia , Fertilidade , Preservação do Sêmen/veterinária , Sêmen/fisiologia , Animais , Cruzamento , Feminino , Congelamento , Inseminação Artificial/veterinária , Lactação , Modelos Lineares , Masculino , Leite , Paridade , Gravidez , Estações do Ano , Preservação do Sêmen/métodos , Pré-Seleção do Sexo/veterinária
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