RESUMO
This study aimed to determine the influence of heat stress during the dry period on milk yield and reproductive performance of Holstein cows in a hot environment. Breeding and milk production records of cows, as well as meteorological data between 2017 and 2020 from a commercial dairy herd (n = 12,102 lactations), were used to determine the relationship between climatic conditions during the dry period (average of the temperature-humidity index (THI) at the beginning, middle, and end of the dry period) and reproductive efficiency and milk yield traits. THI was divided into < 70 (no heat stress), 70-80 (moderate heat stress), and > 80 (severe heat stress). First-service pregnancy rate of cows decreased (P < 0.01) with increasing hyperthermia during the dry period (9.5, 7.3, and 3.4% for THI < 70, 70-80, and > 80, respectively). All-service pregnancy rate was highest (P < 0.01) for cows not undergoing heat stress during the dry period (60.2%) and lowest (42.6%) for cows with severe heat stress during the dry period. Cows not experiencing heat stress during the dry period required a mean ± SD of 5.6 ± 3.8 services per pregnancy compared with 6.5 ± 3.6 (P < 0.01) for cows subjected to THI > 80 during the dry period. Cows not suffering heat stress during the dry period produced more (P < 0.01) 305-day milk (10,926 ± 1206 kg) than cows subjected to moderate (10,799 ± 1254 kg) or severe (10,691 ± 1297 kg) heat stress during the dry period. Total milk yield did not differ (P > 0.10) between cows not undergoing heat stress (13,337 ± 3346 kg) and cows subjected to severe heat stress during the dry period (13,911 ± 4018 kg). It was concluded that environmental management of dry cows during hot months is warranted to maximize reproductive performance and milk yield in the following lactation.
Assuntos
Resposta ao Choque Térmico , Umidade , Lactação , Leite , Reprodução , Animais , Bovinos/fisiologia , Feminino , Reprodução/fisiologia , Resposta ao Choque Térmico/fisiologia , Gravidez , Transtornos de Estresse por Calor/veterinária , Transtornos de Estresse por Calor/fisiopatologia , Temperatura AltaRESUMO
Heat stress (HS) during the dry period of dairy cows in hot and dry conditions compromises the physiological status and mammary gland development of dairy cows, thereby negatively affecting milk component yield in the subsequent lactation. Our objective was to evaluate the effects of cooling Holstein cows under moderate or higher HS conditions (i.e., ambient temperature higher than 30 °C, with a temperature-humidity index of 78.2 units) during the dry period on prepartum physiological status, postpartum productivity, and calf growth. Twenty-four multiparous Holstein cows were divided into two groups: one with a cooling system based on spray and fans under a pen shade (CL, n = 12) and the other not-cooled (NC, n = 12). The cooling system operated 10 h/d (09:00-19:00 h) for 60 d prepartum. During the morning, rectal temperature and respiration frequency were lower in CL cows, but not in the afternoon, which was attributed to higher (P < 0.01) dry matter intake by CL cows. Total serum protein was higher (P < 0.01) in CL cows, but hemoglobin was higher in NC cows (P < 0.01), with no differences in other electrolytes, hormones, hematological components, and metabolites. Milk fat and fat and fat-protein corrected milk were higher (P < 0.05) in CL cows. Female and birth weight trended (P = 0.08) to be higher in CL cows. Cooling cows during the dry period had a limited effect on physiology prepartum but increased postpartum productivity of Holstein cows under hot and dry conditions.
Assuntos
Leite , Período Pós-Parto , Animais , Bovinos/fisiologia , Feminino , Leite/metabolismo , Período Pós-Parto/fisiologia , Gravidez , Estações do Ano , Lactação/fisiologia , Temperatura CorporalRESUMO
Embryo transfer (ET) in bovines was created with the purpose of increasing the pregnancy rate (PR) of animals with high genetic value; however, multiple factors have been found to affect the success of this reproductive biotechnology. These factors are frequently grouped in intrinsic and extrinsic factors. Thus, the objective of the present experiments was to assess the effect of intrinsic and extrinsic factors on the pregnancy rate under tropical conditions. To do this a total of 648 embryo transfer (ET) procedures were performed between January and December 2021. The intrinsic factors were size and location of the corpus luteum, body condition, genetic group, age and parity; while extrinsic factors were location of the farm, environmental comfort, season in which the ET was carried out, prevailing weather conditions, and the preservation, quality, and the development stage of embryos at the time of ET. A χi2 was used for analysis of main effects, and logistic regression analysis to calculate the probability of pregnancy and the association between intrinsic or extrinsic factors; additionally, a multivariate analysis of data clusters was used to find a linkage between the effects. While recipient female age had a negative effect (Odds ratio = 0.345-0.871) on PR (p < 0.05), being higher in younger cows, the rest of the intrinsic factors did not affect the PR. The significant (p < 0.05) extrinsic factors were THI category, season of year and type of embryo preservation, showing that the highest PR (p < 0.05) was obtained in the comfort THI category, during the winter season and using fresh embryos for transfer. The clustering analysis did not show any linkage between PR and intrinsic factors, while a linkage (p < 0.05) was found with season of the year and embryo preservation as extrinsic factors. It is concluded that age of the recipient cow and environmental conditions at the time of the embryo transfer are key factors to be considered for a successful pregnancy rate from in-vitro ET programs using dual-purpose cows under tropical conditions.
Assuntos
Transferência Embrionária , Taxa de Gravidez , Clima Tropical , Animais , Bovinos/fisiologia , Feminino , Gravidez , Transferência Embrionária/veterinária , Estações do AnoRESUMO
The objective of this retrospective study was to assess the effect of receiving a single (n = 50,285) or double (n = 4392) artificial insemination (AI), 12 h apart, within a timed artificial insemination protocol on pregnancy per AI (P/AI) in nulliparous heifers (inseminated with either sex-sorted or conventional semen) and pluriparous Holstein cows in a commercial dairy herd. Also, this study aimed to investigate the relationship between temperature-humidity index (THI) and time of the first AI and fertility. Fertility of cows receiving two AI with normothermia (THI <68) was higher (p < .05) than cows receiving a single AI (42.9% vs. 36.4%). P/AI of cows receiving two AI with severe heat stress (THI >85) was higher (p < .05) than cows receiving a single AI (21.0% vs. 12.6%). Regardless of heat stress conditions, applying the first AI in the morning increased (p < .05) P/AI in cows with double AI than in cows whose first AI occurred in the afternoon (38.4 vs. 33.3%). With moderate heat stress, and sexed-sorted semen, P/AI to timed AI was higher (65.0 vs. 51.9%; p < .05) in heifers receiving double AI than those serviced once. It was concluded that double AI, 12 h apart, enhanced fertility at timed AI than herd mates with a single AI, particularly with heat stress at breeding.
Assuntos
Líquidos Corporais , Sêmen , Gravidez , Bovinos , Animais , Feminino , Estudos Retrospectivos , Inseminação Artificial/veterinária , Fertilidade , Dinoprosta , Sincronização do Estro , Lactação , Progesterona , Hormônio Liberador de GonadotropinaRESUMO
Dorper rams are widely distributed throughout the world under different climatic conditions, however, little is known about their reproductive performance in desert regions. Ten Dorper rams were individually housed and exposed to thermoneutrality for 35 d in spring (23.6 ± 5.6 °C, mean ± SD) and outdoor heat stress (HS) for 35 d in summer (33.6 ± 2.0 °C) to evaluate the effect of seasonal HS on physiological responses, testicular biometry, and seminal quality under desert climatic conditions. Rectal temperature, respiration rate and coat surface temperatures in different body regions were measured every 7 d (0600, 1200, and 1800 h); also, testicular biometry was registered at 0600 h. Semen was collected via an artificial vagina 3 d after physiological variables were measured and seminal traits were evaluated. Rectal temperature, respiration rate and coat surface temperatures were higher (P < 0.01) at each hour of measurement in summer compared to spring. Overall, scrotal length and circumference, as well as testicular volume were higher (P < 0.01) in summer than in spring. Compared to spring conditions, summer HS caused lower (P ≤ 0.05) sperm concentration and viability combined with a higher percentage of sperm abnormalities without affecting ejaculate volume. Both mass and sperm motility were similar between seasons in the first two sampling weeks, and then decreased (P ≤ 0.03) due to summer HS. In conclusion, Dorper rams developed testicle hyperthermia and, consequently, showed poor semen quality due to the high environmental temperatures prevailing in desert regions.
Assuntos
Análise do Sêmen , Testículo , Feminino , Masculino , Ovinos , Animais , Testículo/fisiologia , Estações do Ano , Sêmen/fisiologia , Clima Desértico , Motilidade dos Espermatozoides , Carneiro Doméstico/fisiologia , Espermatozoides/fisiologia , Regulação da Temperatura Corporal , Resposta ao Choque TérmicoRESUMO
Two experiments were conducted to evaluate the effect of intramuscular administration of minerals during a TAI program on the reproductive responses of lactating Angus cows. All cows (n=353) were subjected to a 9-day TAI program based on CIDR insertion plus injections of estradiol, cloprostenol, and eCG, and then TAI 48 h later. In experiment 1, two groups were randomly created, one control with a placebo injection (CON, n=109), and the second received 10 mL of Fosfosan® (MIN, n=172) on day 0 of the synchronization. Conception rate (66.9 vs. 55%) and estrus percentage (55.8 vs. 44%) were higher (P≤0.05) in MIN than in CON cows. Given these results, a second experiment was conducted randomly assigning the cows to two treatments (n=36 each): a single injection of 10 mL of Fosfosan® (MIN-O) on day 0 or two injections of 10 mL of Fosfosan® (MIN-T) on synchronization days 0 and 7. Four cows of each treatment were randomly selected to be scanned with transrectal ultrasound before and during the synchronization protocol to assess ovarian structures and cyclicity, and at day 39 post-TAI for pregnancy diagnosis. Also, blood samples were obtained for the determination of serum minerals and progesterone (P4) concentrations. The number of mineral injections did not affect conception rate (P≥0.1229) conception rate, serum mineral and P4 concentrations, number, and size of emerging follicles, or follicle size according to 1 to 4 classifications. The MIN-T promoted (P<0.05) earlier follicular wave emergence than MIN-O. However, MIN-O cows had a dominant follicle of 15.12 mm, which is more significant (P<0.05) than that in MIN-T cows (13.5 mm). In conclusion, providing a single mineral injection of Fosfosan® at the start of a TAI program is an excellent reproductive strategy in lactating Angus cows to improve the dominant follicle growth, estrus response, and conception rate.
Assuntos
Lactação , Ovário , Animais , Bovinos , Feminino , Gravidez , Suplementos Nutricionais , Inseminação Artificial/veterinária , Ovário/diagnóstico por imagem , ReproduçãoRESUMO
The objective of this study was to develop an equation to predict rectal temperature (RT) using body surface temperatures (BSTs), physiological and climatic variables in pubertal Holstein heifers in an arid region. Two hundred Holstein heifers were used from July to September during two consecutive summers (2019 and 2020). Respiratory frequency (RF) was used as a physiological variable and ambient temperature, relative humidity and temperature-humidity index as climatic variables. For the body surface temperatures, infrared thermography was used considering the following anatomical regions: shoulder, belly, rump, leg, neck, head, forehead, nose, loin, leg, vulva, eye, flank, and lateral area (right side). Initially, a Pearson correlation analysis examined the relationship among variables, and then multiple linear regression analysis was used to develop the prediction equation. Physiological parameters RT and RF were highly correlated with each other (r = 0.73; PË0.0001), while all BST presented from low to moderate correlations with RT and RF. BST forehead temperature (FH) showed the highest (r = 0.58) correlation with RT. The equation RT = 35.55 + 0.033 (RF) + 0.030 (FH) + ei is considered the best regression equation model to predict RT in Holstein heifers in arid zones. This decision was made on the indicators R2 = 60%, RMSE = 0.25, and AIC = 0.25, which were considered adequate variability indicators.
Assuntos
Temperatura Corporal , Termografia , Bovinos , Animais , Feminino , Temperatura , Umidade , RespiraçãoRESUMO
Sustainability of dairy production depends largely on reproductive efficiency that is affected by heat stress due to high ambient temperature and humidity during summer. Supplementation of minerals has been proposed as a management strategy to minimize adverse impact of heat stress on fertility. The objective of this study was to determine the effects of an injectable mineral supplement (Fosfosan) containing selenium (Se), copper (Cu), potassium (K), magnesium (Mg) and phosphorus (P) on the ovarian structures, reproductive hormones and conception rate of heat-stressed Holstein cows. Sixteen cows were assigned during summer to one of two treatments, a control group (CON; n = 8) and a mineral-supplemented group (SUP; n = 8). Ambient temperature and relative humidity records were collected and processed to estimate the temperature-humidity index (THI), which confirmed a heat-stressed environment during the study (avg. THI = 79.4). Cows were subjected to a fixed-time artificial insemination (FTAI) program using the CIDR-Synch synchronization protocol. Traits indicative of ovarian activity were recorded during and after this protocol, as well as serum concentrations of reproductive hormones. Pregnancy diagnosis was made 28 and 35 d after FTAI. A completely randomized block design with repeated measures over time was performed to study ovarian functional structures and its hormonal profiles. Correlations and regressions were estimated to study relationships between ovarian structures and related hormones. Mineral supplementation did not increase follicular diameter or follicular populations (p > .05), yet tended to increase corpus luteum diameter (p < .10), and it enhanced (p < .01) oestrogen and progesterone serum concentrations and improved (p < .05) cow's conception rate. Diameter of dominant follicles and corpus luteum was correlated (p < .05) with oestrogen and progesterone levels, respectively, but only in mineral-treated cows. Two additional dairy herds were evaluated to confirm that mineral supplementation improved conception rate during the heat stress period (objective 2). Cows from dairy 1 received FTAI during winter (n = 401) and summer (n = 240), whereas cows from dairy 2 were bred after natural detected oestrus during winter (n = 558) and summer (n = 314). Conception rates were higher (p < .05) in winter than summer and they improved (p < .05) with mineral supplementation, but only in cows managed during summer. In conclusion, supplementation of minerals enhanced hormonal secretion from ovarian structures and improved conception rate in Holstein cows exposed to summer heat stress.
Assuntos
Doenças dos Bovinos , Transtornos de Estresse por Calor , Animais , Bovinos , Suplementos Nutricionais , Estrogênios/farmacologia , Sincronização do Estro , Feminino , Transtornos de Estresse por Calor/veterinária , Inseminação Artificial/veterinária , Lactação , Gravidez , Progesterona , ReproduçãoRESUMO
The traditional goat production systems on arid and semi-arid rangelands of northern Mexico are characterized by minimum external inputs; therefore, little is known about goat response to technological improvements. This observational study aimed to ascertain the effect of using improved goat production technologies and breed on milk yield and reproductive performance of goats on rangeland. The study was conducted from January 2017 to June 2018. Thirty-seven goat herds comprising 6393 animals were used. Goats supplemented with 250 g of concentrate (S-goats; 14% crude protein) 30 days before breeding produced significantly more daily milk yield (218 ± 61 vs. 200 ± 60 g) than the unsupplemented (UNS-goats) goats. Milk production per lactation was 12 percentage points greater in goats with access to plain salt throughout the year than those without salt access. The absence of deworming significantly depressed daily milk yield (189 ± 55 vs. 221 ± 61 for non-treated and treated goats). In 5 months, the lowest total milk yield was for Boer goats (26.9 ± 8.3 kg) and the highest for Nubian goats (36.1 ± 9.2 kg). The kidding rate was significantly higher in the S-goats than in the UNS-goats group (66.9 vs. 62.8%). Salt-supplemented goats had a significantly greater kidding rate than goats not receiving salt (68.5 vs. 61.2%). The lowest kidding rate was for Saanen goats and the highest for Nubian goats (66.2%). These findings indicate that milk yield and reproductive performance were primarily influenced by supplementing grazing goats with concentrates and salt in this semi-arid rangeland.
Assuntos
Cabras , Leite , Animais , Suplementos Nutricionais , Feminino , Cabras/fisiologia , Lactação/fisiologia , Leite/metabolismo , ReproduçãoRESUMO
Heat stress is a great challenge for feedlot operations established in arid zones. The aim of this study was to evaluate if increasing shade area in the pen improved physiological and productive variables in feedlot heifers under hot climate. A total of 510 European and Zebu heifers were randomly assigned to six pens which were divided in two treatments: (1) three pens with 100 heifers each with a shade area of 2.7 m2/head (control group [C]); and (2) three pens with 70 heifers each with a shade area of 3.7 m2/head (treated group [T]). Physiological variables respiratory frequency (RF) and body surface temperature (BST) of several anatomic regions were taken from 30 heifers per treatment (i.e., 10 heifers/pen). Feed intake on pen basis was recorded weekly and heifers were individually weighted on days 1, 26, and 66 of the study to calculate performance variables. Relative humidity (RH) and ambient temperature (AT) were recorded and used to estimate the temperature-humidity index (THI). Data was analyzed with analysis of variance. The average THI during the study was 81.7 units, which was categorized as dangerous heat stress. In both shaded areas, European heifers showed higher (P < 0.05) RF than Zebu heifers. In the afternoon, the temperature of head, neck, loin, paddle, and belly was higher (P < 0.05) in C compared with T. Heifers under T showed better (P < 0.05) daily weight gain (DWG), total weight gain (TWG), feed conversion (FC), and feed efficiency (FE) than heifers in C, with no effect on dry matter intake (DMI). Results indicate that during hot summer months, Zebu showed more tolerance to heat stress than European heifers; however, heifers under a shade area of 3.7 m2/head had better productive performance than those under a shade area of 2.7 m2/head during the finishing phase of the feedlot. Increasing the shade area in the finishing phase of beef cattle on feedlot improved some physiological and productive responses during heat stress.
Assuntos
Doenças dos Bovinos , Transtornos de Estresse por Calor , Animais , Temperatura Corporal , Bovinos , Ingestão de Alimentos/fisiologia , Feminino , Transtornos de Estresse por Calor/veterinária , Resposta ao Choque Térmico , Estações do AnoRESUMO
The objective was to determine the effects of feeding soybean oil (SBO), an ingredient rich in n-6 polyunsaturated fatty acids (PUFA), to late gestation hair ewes on physiological responses, feedlot performance, and serum metabolite and electrolyte concentrations of their growing ewe lambs under outdoor heat stress conditions. Twenty-four Dorper × Pelibuey ewe lambs weaned (body weight = 21.5 ± 0.2 kg, age= 2 months, and multiple birth) born from ewes fed 0, 30, or 60 mg of SBO/kg dry matter (DM) during late gestation were selected (n = 8/treatment) to conduct a 30-day feeding trial during the summer season of a desert region (temperature = 34 °C and temperature-humidity index = 35 units). While rectal temperature was unaffected in any daytime, respiratory rate in the afternoon quadratically increased (P = 0.05) as the SBO levels increased from 0 to 60 mg/kg DM in the maternal diet. Final weight, average daily gain, and feed efficiency linearly increased (P = 0.04) with increasing levels of SBO. Body surface temperatures and serum concentration of glucose, cholesterol, triglyceride, total protein, urea, sodium, potassium, and chlorine did not vary by the SBO inclusion in the maternal diet. In conclusion, feeding late gestation hair ewes with source rich in n-6 PUFA appears to be an effective maternal nutritional strategy to improve post-weaning growth without compromising the thermoregulatory ability of their growing offspring under a heat stress environment.
Assuntos
Fenômenos Fisiológicos da Nutrição Animal , Transtornos de Estresse por Calor , Ração Animal/análise , Animais , Regulação da Temperatura Corporal , Dieta , Suplementos Nutricionais , Ácidos Graxos Ômega-6 , Feminino , Transtornos de Estresse por Calor/veterinária , Resposta ao Choque Térmico , Gravidez , OvinosRESUMO
Impacts of an additional cooling event during the night on physiological and productive parameters of two breeds (B) of dairy cows under severe heat stress conditions were determined. Fifteen Holstein (H) and 15 Jersey x Holstein (JxH) cows were assigned to one of the two cooling strategies (CS), where the difference was an added 1 h cooling event during the night (i.e., 3X and 4X cooling events) with the 4X group having the added night cooling event. Maximum and minimum average temperature/humidity indices during the study were 86 and 77 units, respectively. There were no CS x B interactions for any response variable. Body condition score (BCS) was similar between CS, but H cows had higher (P<0.05) condition than JxH. There were no differences in rectal temperature due to CS or B. Respiration rate between breeds and cooling strategies were similar throughout the day. However body surface temperatures of head, thurl, right flank, and udder were higher (P<0.05) in 3X versus 4X cows, and H cows maintained a higher (P < 0.05) temperature in thurl and right flank than JxH during PM hours. Metabolites and hormone concentrations were not affected by CS, but H cows had lower (P < 0.05) triiodothyronine and higher (P < 0.05) thyroxine, than JxH. The 4X cows had higher (P<0.05) milk yield and milk energy output than 3X cows. While H cows produced more milk than JxH, the latter had higher (P < 0.05) milk component levels. In general, JxH cows were judged to have to demonstrate a more desirable physiological response and milk composition outcome than H cows. An additional night cooling event was judged to result in more desirable physiological and productive responses than in cows without this extra night cooling event under the extremely hot and dry environmental conditions during the study.
Assuntos
Transtornos de Estresse por Calor , Lactação , Animais , Temperatura Corporal , Bovinos , Feminino , Transtornos de Estresse por Calor/veterinária , Temperatura Alta , Umidade , LeiteRESUMO
BACKGROUND: Ferulic acid is a natural occurring compound with antioxidant and antimicrobial bioactive properties, and recently was proposed as a new alternative growth promoter in meat-producing animals without changing meat quality parameters. The present study aimed to evaluate the impact of two doses of ferulic acid (FA) on the feedlot performance, carcass traits, and physicochemical and sensory characteristics of meat quality in commercial heifers. Ninety heifers (3/4 Bos taurus; n = 270; body weight = 480 ± 10 kg) were randomly assigned to one of the following treatments (30 days): Control, fed with a basal diet; FA250 or FA500 offered the same diet further supplemented with FA at 250 or 500 mg kg-1 feed, respectively. Feedlot performance, carcass traits, and physicochemical and meat sensory characteristics were evaluated. RESULTS: FA supplementation increased average daily gain (ADG) by 21%, hot carcass weight by 1.8% and cold carcass weight by 1.6% with respect to the control (P < 0.05). FA500 treatment caused a decrease (P < 0.05) in some carcass traits. However, carcass characteristics of economic importance, such as cold carcass dressing and LT muscle area, were improved by FA250 supplementation (P < 0.05), causing a possible growth promoter effect. Physicochemical and sensory parameters of meat were not altered by FA supplementation (P > 0.05). CONCLUSION: Ferulic acid has the potential for use as a growth promoter additive in finishing heifers without negatively affecting the meat quality, as occurs with some synthetic growth promotants compounds used in animal production. © 2020 Society of Chemical Industry.
Assuntos
Bovinos/crescimento & desenvolvimento , Ácidos Cumáricos/metabolismo , Suplementos Nutricionais/análise , Carne/análise , Ração Animal/análise , Animais , Bovinos/metabolismo , Feminino , Humanos , Masculino , Controle de Qualidade , PaladarRESUMO
Our aim was to evaluate the effects of progesterone supplementation after fixed-time artificial insemination (FTAI) on physiological and reproductive variables and serum thyroid hormone concentrations of cooled Holstein heifers during a hot summer season. Sixty-nine Holstein heifers were randomly assigned to three treatments: (1) heifers under visual estrus detection and inseminated according to AM-PM rule (n = 23; control (C)), (2) heifers subjected to FTAI after estrus synchronization using a CIDR insert (n = 24; FTAI group), and (3) heifers treated as the FTAI group plus progesterone supplementation between the day 4 and 14 post-insemination with a reused CIDR device (n = 22; FTAI+SP4 group). All heifers were cooled daily with misting and fans. Physiological variables were measured; likewise, blood samples were collected to determine serum progesterone, thyroxine, and triiodothyronine concentrations. Both respiration rate and rectal temperature were similar among treatments. Conception rate was greater (P < 0.05) in C (65.2%) and FTAI+SP4 (59.1%) heifers than in FTAI heifers (33.3%). Serum triiodothyronine and progesterone concentrations of FTAI+SP4 heifers were similar to those of C heifers but greater (P < 0.05) than those of FTAI heifers. In conclusion, progesterone supplementation post-insemination increased conception rate and serum progesterone concentrations without affecting thermoregulation capacity in Holstein heifers subjected to FTAI and cooling during a hot summer season.
Assuntos
Sincronização do Estro , Progesterona , Animais , Bovinos , Suplementos Nutricionais , Dinoprosta , Feminino , Hormônio Liberador de Gonadotropina , Inseminação Artificial/veterinária , Estações do Ano , Hormônios TireóideosRESUMO
The objective of this study was to evaluate growth performance, and mammary gland parenchyma (PAR) development in Holstein female calves fed whole milk combined with milk replacer for 15% total solids (15TS) or only milk (11% TS; 11TS). The effects of zilpaterol hydrochloride (ZH) and an estrogenic implant (EI) on growth performance, serum metabolites, and PAR development in post-weaning calves (63-90 days of age) fed 15TS or 11TS were also investigated. In the first phase, 78 calves were randomly divided into two groups (n = 39/group), 15TS, or 11TS (5 to 8 L/day; starter ad libitum). After weaning, calves were randomly assigned to four treatments, no EI, EI, ZH, and ZH-EI. In phase 1, 15TS calves had greater (P < 0.01) average body weight at weaning than 11TS calves (82.0 ± 5.8 vs. 74.1 ± 5.7 kg). Pre-weaning average daily gain (718 ± 67 vs. 576 ± 64 g/day) was higher (P < 0.01) for 15TS calves than 11TS calves. Feed/gain (1.5 ± 0.3 vs. 1.8 ± 0.3 kg of DMI/kg of gain) was lower (P < 0.01) for 15TS calves than 11TS calves. PAR area (8.8 ± 3.3 vs. 5.0 ± 1.6 cm2) was greater (P < 0.01) for 15TS calves than 11TS calves. No differences (P > 0.10) in average daily gain (986 ± 79 g/day across treatments) were observed in calves receiving ZH, EI, or ZH-EI fed 15TS or 11TS diets previously. However, the PAR area of 15TS calves administered ZH-EI was 2.2 times greater (P < 0.01) than 11TS calves with no ZH and CI. This study demonstrated the benefits of supplying milk with 15% TS for enhancing overall animal growth and PAR development. Further use of ZH and EI during the post-weaning period did improve mammary PAR growth.
Assuntos
Ração Animal , Leite , Ração Animal/análise , Animais , Peso Corporal , Bovinos , Dieta/veterinária , Feminino , DesmameRESUMO
Tuberculosis remains a significant infectious disease of farm animals and humans worldwide. The objective of this study was to assess various risk factors associated with testing positive for bovine tuberculosis (bTB) in high-yielding Holstein cows in an intensive dry-lot dairy operation. In a retrospective observational study, 9312 records from Holstein cows from a large dairy herd in northern Mexico were used. The incidence rate of lactating cows reactor to bTB was 7.3 cases/100 cow years (95% CI = 6.7-7.9%). Multiple logistic regression models indicated that cows with total milk yield during the first lactation >10,200 kg were 1.3 times (95% confidence intervals (CI) for odds ratio (OR) = 1.2-1.6) more likely to be detected as bTB reactors than cows with total milk yield <10,200 kg (8.2 vs. 6.4%; P < 0.01). The risk of being reactor to bTB increased with xÌ total milk yield/lactation >11,500 kg (OR=2.7, 95% CI = 2.3-3.3; 10.4 vs. 4.2%) compared with cows with xÌ total milk yield/lactation <11,500 kg. Cows with >10,200 kg 305-day milk yield in the last lactation was associated (P < 0.01) with 1.3 times higher odds (95% CI for OR = 1.1-1.5) of being classed as reactors than cows with <10,200 kg. Cows with peak milk yield >48 kg were 1.9 times (95% CI for OR = 1.6-2.2) more likely to be reactor to bTB than cows with peak milk yield <48 kg (9.2 vs. 5.1%; P < 0.01). Cows with either puerperal metritis (OR = 0.07, 95% CI = 0.5-0.9) or carrying twins (OR = 0.05, 95% CI = 0.01-0.19) had a protective role for being reactor to bTB. This study showed that increased milk production was associated with a higher risk of becoming positive to tuberculin skin test in high-yielding Holstein cows.
Assuntos
Doenças dos Bovinos , Tuberculose Bovina , Animais , Bovinos , Feminino , Lactação , México/epidemiologia , Leite , Fatores de Risco , Tuberculose Bovina/diagnóstico , Tuberculose Bovina/epidemiologiaRESUMO
A survey was completed to determine water use by small-scale dairy farms in Mexicali Valley of Mexico and to associate it with dairy production parameters. Mexicali Valley surrounds the capital city of the state Baja California, Mexicali. Sixty-one smallholders were interviewed in person in this rural area of northwestern Mexico. On average, small dairy holders had more than 20 years of experience and were ~ 55 years of age; people working on their farms are especially relatives. A low percentage was literate (20%), and they belong to a local dairy association. Milk yield/cow/year does not reach 4000 kg of milk and 75% of producers do not follow a defined management program for their cattle. Hand-milking is still practiced by 27% of the producers, and there is a general lack of infrastructure to maintain milk in a refrigerated state so that there is a very high risk of zoonotic diseases. Water use efficiency (WUE) was linearly correlated (P < 0.05) with total irrigated area, but not with animal production parameters. Regression equations constructed to explain WUE exhibited low adjustment, and WUE was not associated (P > 0.05) with milk yield. Small dairy producers in Mexicali Valley are in a generally poor situation with low water use practices; however, required more government support to increase their benefits from this livestock activity.
Assuntos
Indústria de Laticínios/estatística & dados numéricos , Fazendas/estatística & dados numéricos , Abastecimento de Água/estatística & dados numéricos , Água/análise , MéxicoRESUMO
The objective of this study was to compare the fertility of Holstein heifers under cooling and inseminated with sexed semen during the summer versus winter season. Eighty heifers were divided into two groups: (1) summer group (n = 40), consisted of heifers under visual heat detection and inseminated with sexed semen. These heifers were also provided with artificial cooling under shade area from 1000 to 1800 h. (2) Winter group (n = 40), heifers under shade only and with the same reproductive protocol than the summer group. The rectal temperature and respiratory rate were higher (P < 0.05) in the summer group. Vaginal temperature presented higher values in summer (P < 0.05) in most of the daylight hours except between 1100 and 1200 h (P > 0.05). Progesterone, as measured from the AI to 21 days after AI, showed higher values (P < 0.05) in days 6, 12, 18, and 21 during summer compared with winter in pregnant heifers; also, non-pregnant heifers had higher concentrations of progesterone on days 6, 9, 15, and 21 (P < 0.05) in winter. The conception rate in winter at day 35 post-AI (65%) was higher (P < 0.05) than those observed during summer (37.5%). In conclusion, although the lower fertility observed during summer with sexed semen, it can be considered as normal and comparable to the conception rate with conventional semen under hot climate.
Assuntos
Fertilização , Inseminação Artificial/veterinária , Progesterona/sangue , Sêmen/fisiologia , Animais , Bovinos , Feminino , México , Gravidez , Estações do AnoRESUMO
This study was conducted to evaluate the effects of hair coat characteristics on thermophysiological variables and body surface temperatures (BST), measured with infrared thermography, as well as milk yield of Holstein cows in a hot environment. Physiological and milk yield variables were assessed using 103 pluriparous Holstein cows. Also, hair angle (HA), density of hair coat (D), diameter of hair (HD), hair length (HL), weight of hair coat (Wt), and coat thickness (CT) were recorded. Biplot analysis (principal components analysis) revealed that HL was closely associated with Wt, CT, and HD and all these variables had a positive association with rectal temperature. Both CT and HL were found to be negatively associated with shoulder and neck temperature; tympanic temperature showed no association with BTS. Cows with short hair coat (length < 17 mm) did not produce more milk in 305 days than cows with longer hair coat (9673 ± 1604 vs. 9277 ± 817; P = 0.12). On the other hand, milk fat percentage at the middle of lactation was higher (P < 0.01) in cows with longer hair relative to cows with coat hair < 17 mm (3.71 vs. 3.35%, respectively). In conclusion, physical characteristics of the coat of Holstein cows were not associated with the 305-day milk yield but cows with longer hair produced a greater milk fat percentage at the middle of lactation compared to cows with short hair.
Assuntos
Bovinos/fisiologia , Temperatura Alta , Lactação/fisiologia , Leite , Animais , Temperatura Corporal , Feminino , CabeloRESUMO
Forty Dorper × Pelibuey sheep females were used to evaluate the effects of physiological state on physiological variables and serum concentrations of metabolites, thyroid hormones, and electrolytes under outdoor heat stress conditions. Females were selected as follows (n = 10 per group): weaning ewe lambs (WEL; 3 months old), replacement nulliparous ewes (RNE; 8 months old), non-pregnant and non-lactating multiparous ewes (NME; 3-4 years old) and lactating multiparous ewes (LME; 3-4 years old). While physiological variables were measured both morning and afternoon, blood samples were collected before feeding in the morning to determine all blood components. Three contrasts were constructed: (1) WEL vs. older ewes, (2) RNE vs. multiparous ewes, and (3) NME vs. LME. Compared with older ewes, WEL had higher (P < 0.01) rectal temperature (RT) and hair coat temperatures through the day, and also higher (P < 0.01) respiratory rate (RR) only in the afternoon. Serum levels of glucose and cholesterol were lower (P ≤ 0.02) in WEL than in older ewes. Nulliparous ewes compared with multiparous had always similar RT but higher (P ≤ 0.05) hair coat temperatures in most of the body regions by the morning and higher (P < 0.01) RR, without difference for hair coat temperatures in the afternoon. Only serum glucose (P = 0.07) and urea nitrogen (P < 0.01) levels were affected by parturition number, being lower in multiparous ewes. Regarding the effect of lactation, while RR was unaffected, afternoon RT and hair coat temperatures in most of the body regions through the day were higher (P ≤ 0.03) in lactating ewes. In addition, LME had lower (P < 0.01) serum levels of glucose, cholesterol, and urea nitrogen, but higher (P = 0.02) triiodothyronine levels than NME. In conclusion, ewe lambs and lactating ewes were less tolerant to heat stress, while nulliparous and multiparous ewes showed similar thermoregulatory ability.