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1.
Int J Mol Sci ; 22(4)2021 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-33670752

RESUMO

The reproductive status of dairy cows remains a challenge for dairy farmers worldwide, with impaired fertility linked to a significant reduction in herd profitability, due in part to impaired immunity, increased metabolic pressure, and longer postpartum anestrous interval (PPAI). Exosomes are nanovesicles released from a variety of cell types and end up in circulation, and carry proteins, bioactive peptides, lipids, and nucleic acids specific to the place of origin. As such, their role in health and disease has been investigated in humans and animals. This review discusses research into exosomes in the context of reproduction in dairy herds and introduces recent advances in mass-spectrometry (MS) based proteomics that have a potential to advance quantitative profiling of exosomal protein cargo in a search for early biomarkers of cattle fertility.


Assuntos
Bovinos/fisiologia , Indústria de Laticínios , Exossomos/metabolismo , Reprodução/fisiologia , Animais , Epigênese Genética , Modelos Biológicos , Proteômica , Reprodução/genética
2.
Schweiz Arch Tierheilkd ; 163(2): 123-138, 2021 Feb.
Artigo em Alemão | MEDLINE | ID: mdl-33528363

RESUMO

INTRODUCTION: Introduction The impact of lameness on milk yield in dairy cows has been investigated already in many countries by several authors, taking into consideration almost exclusively locomotion scores ≥ 3. The aim of this study was to evaluate the impact of lameness and of the various lameness scores (2-5) on milk yield and milk solids in cows of the three most important dairy cattle breeds (Fleckvieh, Braunvieh, Holstein-Friesian) in Austria within one lactation period. Material and methods Locomotion scoring of dairy cows was performed by trained personnel every 30-40 days in 2014 during the course of routine performance testing. From the recorded locomotion scores (1-5) and the number of lameness episodes, the cows were classified into five lactation-locomotion-score-groups (LLS-G1-5). In total, data sets of 4005 cows from 144 dairy farms across Austria could be evaluated. Using two statistical models the fixed effects on LLS group, breed (evaluation across all breeds in model 1), farm, year and season of calving, parity and the «continuous effect¼ number of milking days were included in the analyses of milk, fat and protein yield. Results The mean, cumulative lameness prevalence during the observation period was 51.0%, and 8.1% were cows from the LLS-G5 group showing repeated and severe locomotion scores. During the first 100 days in milk 34.7% of all cows were lame. In model 1, all effects considered had a significant impact (P .


Assuntos
Bovinos/fisiologia , Lactação , Coxeadura Animal/fisiopatologia , Animais , Áustria/epidemiologia , Indústria de Laticínios , Feminino , Lactação/fisiologia , Coxeadura Animal/epidemiologia , Leite/química , Prevalência
3.
J Anim Sci ; 99(1)2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33523183

RESUMO

The objective of this study was to investigate the effects of processing index (PI) of barley grain and dietary undigested neutral detergent fiber (uNDF) concentration on dry matter (DM) intake, chewing activity, ruminal pH and fermentation characteristics, total tract digestibility, gastrointestinal barrier function, and blood metabolites of finishing beef heifers. The PI was measured as the density after processing expressed as a percentage of the density before processing, and a smaller PI equates to a more extensively processed. Six ruminally cannulated heifers (average body weight, 715 ± 29 kg) were used in a 6 × 6 Latin square design with three PI (65%, 75%, and 85%) × 2 uNDF concentration (low and high; 4.6% vs. 5.6% of DM) factorial arrangement. The heifers were fed ad libitum a total mixed ration consisting of 10% barley silage (low uNDF), or 5% silage and 5% straw (high uNDF), 87% dry-rolled barley grain, and 3% mineral and vitamin supplements. Interactions (P < 0.01) of PI × uNDF were observed for DM intake, ruminating and total chewing time, and DM digestibility in the total digestive tract. Intake of DM, organic matter (OM), starch, and crude protein (CP) did not differ (P > 0.14) between low and high uNDF diets, but intakes of NDF and acid detergent fiber were greater (P = 0.01) for high uNDF diets regardless of barley PI. Heifers fed high uNDF diets had longer (P = 0.05) eating times (min/d or min/kg DM) and tended (P = 0.10) to have longer total chewing times (min/kg DM) than those fed low uNDF diets. Additionally, heifers sorted (P = 0.01) against long particles (>19 mm) for high uNDF diets but not for low uNDF diets. Altering PI of barley grain did not affect (P > 0.12) total volatile fatty acid (VFA) concentration, molar percentages of individual VFA, or duration of ruminal pH < 5.8 and <5.6. Total VFA concentration was less (P = 0.01), acetate percentage was greater (P = 0.01), and duration of ruminal pH < 5.8 and <5.6 was less (P = 0.05) for high compared with low uNDF diets. Digestibility of DM, OM, and CP was greater (P = 0.02) for low vs. high uNDF diets with PI of 65% and 75%, with no difference between low and high uNDF diets at PI of 85%. Blood metabolites and gastrointestinal tract barrier function were not affected (P ≥ 0.10) by the treatments. These results suggest that increasing dietary uNDF concentration is an effective strategy to improve ruminal pH status in finishing cattle, regardless of the extent of grain processing, whereas manipulating the extent of barley processing did not reduce the risk of ruminal acidosis.


Assuntos
Bovinos/metabolismo , Fibras na Dieta/metabolismo , Digestão/fisiologia , Hordeum , Rúmen , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Bovinos/fisiologia , Dieta/veterinária , Fibras na Dieta/administração & dosagem , Feminino , Fermentação , Concentração de Íons de Hidrogênio , Mastigação , Nutrientes , Rúmen/química , Rúmen/metabolismo
4.
Trop Anim Health Prod ; 53(1): 99, 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33415567

RESUMO

The objective of this study was to evaluate the replacement of forage sorghum silage (FS silage) with BRS 716 biomass sorghum silage (BRS 716 silage) in diet of F1 ½ Holstein × ½ Zebu cows on their nutrient intake and digestibility, ingestive behavior, nitrogen balance, and milk yield and composition. The experimental design was in two 5 × 5 Latin squares, simultaneous, composed, each, by five animals, five treatments, and five experimental periods. The study included 10 cows with an initial body weight (BW) of 544 ± 12.84 and 88 ± 14 days of lactation at the beginning of the experiment. The treatments were defined by replacement FS silage at levels 0, 25, 50, 75, and 100% with BRS 716 silage. The roughage:concentrate ratio in the total dry matter (DM) of the diets was 75:25. The replacement of FS silage with BRS 716 silage reduced (p < 0.01) the dry matter intake and digestibility of dry matter, but it had not changed average milk yield (12.68 kg/day; p = 0.94), feed efficiency, body weight, the score of body condition, and the average daily gain of the cows. The milk composition was not changed except casein/total protein in milk that decreased and that increased linearly milk urea nitrogen. The inclusion of BRS 716 silage increased the activities of rumination and chewing and decreased the periods of feeding and idleness. The replacement of up to 100% of FS silage with BRS 716 silage in the diet of F1 Holstein × Zebu cows does not alter average milk yield, despite changing diet intake and digestibility.


Assuntos
Biomassa , Bovinos/fisiologia , Dieta/veterinária , Digestão , Lactação , Silagem/análise , Sorghum/química , Fenômenos Fisiológicos da Nutrição Animal , Animais , Feminino
5.
Trop Anim Health Prod ; 53(1): 70, 2021 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-33398462

RESUMO

Animal's well-being, growth, and production are modulated by environmental conditions, and managemental practices and can be deleteriously affected by global warming phenomenon. In the recent years, unprecedented climatic fluctuations like sustained higher temperatures and humidity, heat waves, and solar flares have led to economic losses in $ billions to both milk and meat industry. It is estimated that by 2050, the US dairy industry alone will borne more than $1.7 billion loss. As human dependency on animal products like milk, meat, and eggs for nutrition is exponentially rising, there is urgency for maximum production. The high yielding animals are already under tremendous metabolic pressure making them more susceptible to adverse climatic conditions. When exposed to heat stress, livestock display a variety of behavioral and physiological acclimatization as essential survival strategies, but at the cost of decreased milk, meat, or egg production. Most of the studies have explored the heat stress in animals and its effect on different milk productions in a specific region or country. A clear understanding of the impact of global warming on dairy enterprise is yet to be comprehended. So this exploratory study will analyze impact of global warming on current milk production trends, economics, and future perspectives.


Assuntos
Bovinos/fisiologia , Indústria de Laticínios , Cabras/fisiologia , Resposta ao Choque Térmico , Leite/metabolismo , Carneiro Doméstico/fisiologia , Animais , Indústria de Laticínios/economia , Indústria de Laticínios/estatística & dados numéricos , Indústria de Laticínios/tendências
6.
Trop Anim Health Prod ; 53(1): 102, 2021 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-33417076

RESUMO

The present study was aimed at evaluating the differences of ovarian follicular dynamics and circulating progesterone (P4) concentrations between crossbred Holstein heifers that ovulated and did not ovulate after a P4-based synchronization protocol. Twenty-one crossbred (Holstein × Thai native) heifers with random stages of the oestrous cycle were subjected to the ovulation synchronization protocol, using an intravaginal P4-releasing device (Eazi-Breed CIDR®) for 7 days. Out of 21 CIDR-treated heifers, 14 ovulating heifers were classified as the ovulatory group and 7 non-ovulating heifers were considered the anovulatory group. The heifers having new wave emergence in ovulatory and anovulatory groups were 11/14 (78.6%) and 4/7 (57.1%), respectively. In ovulating heifers, the mean (± SEM) diameter of preovulatory follicle (PF, mm) was significantly larger, compared to non-ovulating heifers (7.21 ± 0.32 versus 4.04 ± 0.44; P = 0.001), while the mean (± SEM) follicular growth rates (mm/d) in non-ovulating heifers tended to be lower, compared to ovulating heifers (0.73 ± 0.17 versus 1.06 ± 0.08; P = 0.07). The mean (± SEM) circulating P4 concentration (ng/ml) throughout the CIDR protocol (0-10 days) in non-ovulating heifers was significantly higher, in comparison with ovulating heifers (2.82 ± 0.27 versus 1.83 ± 0.16; P = 0.02). However, no significant difference in the mean corpus luteum volume between groups was observed. In conclusion, the present results suggested that elevated circulating P4 concentrations and smaller PF diameters could cause ovulation failure in crossbred Holstein heifers, following a 7-day CIDR-based synchronization protocol.


Assuntos
Bovinos/fisiologia , Folículo Ovariano/fisiologia , Ovulação/fisiologia , Progesterona/sangue , Animais , Ciclo Estral , Sincronização do Estro , Feminino
7.
J Dairy Sci ; 104(2): 1855-1863, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309350

RESUMO

The aims of the present study were to provide a portrait of the techno-economic status of dairy herds in Minas Gerais, Brazil, particularly with respect to bulk-tank somatic cell count (BTSCC) data, and to examine the herd-level associations of BTSCC with various economic performance indicators (EPI). Data from 543 herds, 1,052 herd-year records in total, spread over 3 years (2015-2017), from the South and Southwest mesoregions of Minas Gerais State were provided by the Brazilian Support Agency to Micro and Small Companies Division Minas Gerais (SEBRAE). Herds had an average of 82 lactating cows per herd, milk yield of 17 L/cow per day, and availability of financial information via routine monthly economic surveys. The EPI data (revenue, gross margin, GM; net margin, NM; profit; break-even point; and operational profitability) of each herd was measured monthly by SEBRAE personnel, and herd-year averages of all variables were computed. Bulk-tank data (SCC, total bacterial count, content of crude protein and fat) taken by producers or dairy processors were recorded by SEBRAE personal; and corresponding herd-year averages were calculated and included in the SEBRAE database. There were 209 selected herds, which passed all edit checks, and which had data for all 3 years. The EPI (all expressed on a per-cow basis, $/cow per year) were analyzed, including the effects of region, year, log (ln) BTSCC, production level, and herd size, together with the random effect of herd nested within region. A high proportion of herds (94.6%) presented data records (herd-years) with an average BTSCC > 200 × 103 cells/mL: 37.8% of herd-year records had BTSCC between >200 and ≤400, 14.5% with BTSCC between >400 and ≤500, 25% with BTSCC between >500 and ≤750, and 17.3% with BTSCC >750. For each unit increase in ln BTSCC, revenue declined by $228.5/cow per year, GM by $155.6/cow per year, and profit by $138.6/cow per year. Herds with cows of lower production (<14 kg/d) presented lower GM ($286.8/cow per year) compared with herds containing cows producing ≥14 kg/d (≥14 and <19 kg/d = $446.5, and ≥19 kg/d = $601.9). The small-scale milk producers (<39 lactating cows) presented lower revenue ($1,914.9/cow per year) and GM ($274.5/cow per year) and consequently a negative profit (-$224.1/cow per year) compared with other herd size categories (≥39 lactating cows). The reduction in milk yield was 641 L/cow per lactation for each unit increase in ln BTSCC; this represented 9.4% of the milk yield per lactation, assuming an average milk production of 6,843.3 L/cow per lactation of cows from herds that had BTSCC ≤ 200 × 103 cells/mL. Consequently, we found a negative association of BTSCC with profit; profit declining from $227.0 to -53.1/cow per year when the BTSCC increased from 100 to 750 × 103 cell/mL. In short, the lower the BTSCC, the greater the revenue, GM and NM, profit, and operational profitability of the herds. The reduction of milk yield was the main factor associated with higher BTSCC.


Assuntos
Bovinos/fisiologia , Indústria de Laticínios/economia , Lactação/fisiologia , Leite/citologia , Animais , Brasil , Contagem de Células/veterinária , Indústria de Laticínios/métodos , Feminino , Renda/estatística & dados numéricos , Inquéritos e Questionários
8.
J Dairy Sci ; 104(2): 1881-1886, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309351

RESUMO

Liner overpressure is a quantitative variable indicating the extent to which the vacuum difference across the liner during phase d (the liner compression phase) of milking machine pulsation exceeds the vacuum difference that would be just sufficient to stop milk flow from the teat. Previously defined methods of determining liner overpressure have required modifications to the milking machine, complex instrumentation, or both. Our method of measuring derived overpressure (OP) offers relatively simple instrumentation and realistic milking machine characteristics. We determined derived OP by measuring the duration of milk flow within a pulsation cycle, and then comparing that duration with the shape of the pulsation curve to deduce the pulsation chamber vacuum level corresponding to that duration. Derived OP by our method yielded measurements of OP that differed by less than 2.0 kPa from those determined by the most practical previous method, for 2 trial liners. Derived OP can serve as a method for comparing and evaluating liners, and the method we developed may also be applied to automatic control of the milking process.


Assuntos
Bovinos/fisiologia , Indústria de Laticínios/instrumentação , Indústria de Laticínios/métodos , Lactação/fisiologia , Glândulas Mamárias Animais/fisiologia , Pressão , Animais , Feminino , Leite , Vácuo
9.
J Dairy Sci ; 104(2): 1777-1793, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309365

RESUMO

The objective of this study was to extend a stable isotope-based assessment of AA absorption from rumen-degradable protein (RDP) sources to include determination of essential AA (EAA) availability from microbial protein (MCP). To demonstrate the technique, a study using a 2 × 2 factorial arrangement of treatments applied in a repeated 4 × 4 Latin square design was undertaken. Factors were high and low rumen-degradable protein and high and low starch. Twelve lactating cows were blocked into 3 groups according to days in milk and randomly assigned to the 4 treatment sequences. Each period was 14 d in length with 10 d of adaption followed by 4 d of ruminal infusions of 15N-labeled ammonium sulfate. On the last day of each period, a 13C-labeled AA mixture was infused into the jugular vein over a 6-h period to assess total AA entry. Rumen, blood, urine, and milk samples were collected during the infusions. Ruminal bacteria and blood samples were assessed for AA enrichment. Total plasma AA absorption rates were derived for 6 EAA from plasma 13C AA enrichment. Absorption of 6 EAA from MCP was calculated from total AA absorption based on 15N enrichment in blood and rumen bacteria. Essential AA absorption rates from total protein, MCP, and rumen-undegradable protein were derived with standard errors of the mean of 6, 14, and 14%, respectively. An average of 45% of absorbed EAA were from MCP, which varied among 6 EAA and was interactively affected by starch and RDP in diets. Microbial AA availability measured by isotope dilution method increased with the high RDP diets and was unaffected by starch level, except for Met, which decreased with high starch. Microbial protein outflow, estimated from urinary purine derivatives, increased with RDP and was not significantly affected by starch. This was consistent with measurements from the isotope dilution method. Total AA absorption rates measured from isotope dilution were similar to estimates from CNCPS (v. 6.55), but a lower proportion of absorbed AA was derived from MCP for the former method. Compared with the isotope and CNCPS estimates, the Fleming model underestimated microbial EAA and total EAA availability. An average of 58% of the absorbed EAA was converted into milk, which varied among individual AA and was interactively affected by starch and RDP in diets. The isotope dilution approach is advantageous because it provides estimates of EAA availability for individual EAA from rumen-undegradable protein and MCP directly with fewer errors of measurement than can be achieved with intestinal disappearance methods.


Assuntos
Aminoácidos Essenciais/farmacocinética , Bactérias/metabolismo , Bovinos/fisiologia , Proteínas na Dieta/metabolismo , Rúmen/metabolismo , Rúmen/microbiologia , Aminoácidos Essenciais/administração & dosagem , Aminoácidos Essenciais/metabolismo , Animais , Disponibilidade Biológica , Dieta/veterinária , Feminino , Lactação/fisiologia , Leite/química , Amido/metabolismo
10.
J Dairy Sci ; 104(2): 1591-1603, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309372

RESUMO

The objectives of this experiment were to determine the effects of increased diet fermentability and polyunsaturated fatty acids (FA) with or without supplemental 2-hydroxy-4-(methylthio)-butanoic acid (HMTBa), isoacids (IA; isobutyrate, 2-methylbutyrate, isovalerate, and valerate) or the combination of these on milk fat depression (MFD). Ten Holstein cows (194 ± 58 DIM, 691 ± 69 kg BW, 28 ± 5 kg milk yield) were used in a replicated 5 × 5 Latin square design. Treatments included a high-forage control diet (HF-C), a low-forage control diet (LF-C) causing MFD by increasing starch and decreasing neutral detergent fiber (NDF), the LF-C diet supplemented with HMTBa at 0.11% (28 g/d), the LF-C diet supplemented with IA at 0.24% of dietary dry matter (60 g/d), and the LF-C diet supplemented with HMTBa and IA. Preplanned contrasts were used to compare HF-C versus LF-C and to examine the main effects of HMTBa or IA and their interactions within the LF diets. Dry matter intake was greater for LF-C versus HF-C, but milk yield remained unchanged. The LF-C diet decreased milk fat yield (0.87 vs. 0.98 kg/d) but increased protein yield compared with HF-C. As a result, energy-corrected milk was lower (28.5 vs. 29.6 kg/d) for LF-C versus HF-C. Although the concentration of total de novo synthesized FA in milk fat was not affected, some short- and medium-chain FA were lower for LF-C versus HF-C, but the concentrations of C18 trans-10 isomers were not different. Total-tract NDF apparent digestibility was numerically lower (42.4 vs. 45.6%) for LF-C versus HF-C. As the main effects, the decrease in milk fat yield observed in LF-C was alleviated by supplementation of HMTBa through increasing milk yield without altering milk fat content and by IA through increasing milk fat content without altering milk yield so that HMTBa or IA, as the main effects, increased milk fat yield within the LF diets. However, interactions for milk fat yield and ECM were observed between HMTBa and IA, suggesting no additive effect when used in combination. Minimal changes were found on milk FA profile when HMTBa was provided. However, de novo synthesized FA increased for IA supplementation. We detected no main effect of HMTBa, IA, and interaction between those on total-tract NDF digestibility. In conclusion, the addition of HMTBa and IA to a low-forage and high-starch diet alleviated moderate MFD. Although the mechanism by which MFD was alleviated was different between HMTBa and IA, no additive effects of the combination were observed on milk fat yield and ECM.


Assuntos
Ácido Butírico/administração & dosagem , Bovinos/fisiologia , Suplementos Nutricionais/análise , Ácidos Graxos/química , Glicolipídeos/metabolismo , Glicoproteínas/metabolismo , Gotículas Lipídicas/metabolismo , Leite/metabolismo , Ração Animal/análise , Animais , Dieta/veterinária , Carboidratos da Dieta/administração & dosagem , Fibras na Dieta/metabolismo , Ingestão de Alimentos , Ácidos Graxos/metabolismo , Ácidos Graxos Insaturados/administração & dosagem , Ácidos Graxos Voláteis/química , Ácidos Graxos Voláteis/metabolismo , Feminino , Fermentação , Glicoproteínas/efeitos dos fármacos , Lactação , Gotículas Lipídicas/efeitos dos fármacos , Metionina/análogos & derivados , Leite/química , Nutrientes/metabolismo , Amido/administração & dosagem
11.
J Dairy Sci ; 104(2): 1794-1810, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309382

RESUMO

Kernel processing and theoretical length of cut (TLOC) of whole-plant corn silage (WPCS) can affect feed intake, digestibility, and performance of dairy cows. The objective of this study was to evaluate for lactating dairy cows the effects of kernel processing and TLOC of WPCS with vitreous endosperm. The treatments were a pull-type forage harvester without kernel processor set for a 6-mm TLOC (PT6) and a self-propelled forage harvester with kernel processor set for a 6-mm TLOC (SP6), 12-mm TLOC (SP12), and 18-mm TLOC (SP18). Processing scores of the WPCS were 32.1% (PT6), 53.9% (SP6), 49.0% (SP12), and 40.1% (SP18). Twenty-four Holstein cows (139 ± 63 d in milk) were blocked and assigned to six 4 × 4 Latin squares with 24-d periods (18 d of adaptation). Diets were formulated to contain 48.5% WPCS, 15.5% citrus pulp, 15.0% dry ground corn, 9.5% soybean meal, 6.8% low rumen degradability soybean meal, 1.8% calcium soap of palm fatty acids (FA), 1.7% mineral and vitamin mix, and 1% urea (dry matter basis). Nutrient composition of the diets (% of dry matter) was 16.5% crude protein, 28.9% neutral detergent fiber, and 25.4% starch. Three orthogonal contrasts were used to compare treatments: effect of kernel processing (PT6 vs. SP6) and effect of TLOC (particle size; SP6 vs. SP12 and SP12 vs. SP18). Cows fed SP6 produced 1.2 kg/d greater milk yield with no changes in dry matter intake, resulting in greater feed efficiency compared with PT6. Cows fed SP6 also produced more milk protein (+36 g/d), lactose (+61 g/d), and total solids (+94 g/d) than cows fed PT6. The mechanism for increased yield of milk and milk components involved greater kernel fragmentation, starch digestibility, and glucose availability for lactose synthesis by the mammary gland. However, cows fed SP6 had lower chewing time and tended to have greater levels of serum amyloid A compared with PT6. Milk yield was similar for SP6 and SP12, but SP12 cows tended to have less serum amyloid A with greater chewing time. Cows fed SP18 had lower total-tract starch digestibility and tended to have lower plasma glucose and produce less milk compared with cows fed SP12. Compared with PT6, feeding SP6 raised linear odd-chain FA concentration in milk. Similarly, a reduction of these same FA occurred for SP12 compared with SP6. Cows fed SP6 had greater proportion of milk C14:1 and C16:1 compared with PT6 and SP12. Lesser trans C18:1 followed by greater C18:0 concentrations were observed for SP12 and PT6 compared with SP6, which is an indication of more complete biohydrogenation in the rumen. Under the conditions of this study, the use of a self-propelled forage harvester with kernel processing set for a 12-mm TLOC is recommended for WPCS from hybrids with vitreous endosperm.


Assuntos
Bovinos/fisiologia , Endosperma/metabolismo , Manipulação de Alimentos/métodos , Silagem/análise , Zea mays/metabolismo , Animais , Fibras na Dieta/metabolismo , Ingestão de Alimentos , Feminino , Lactação/fisiologia , Lactose/metabolismo , Leite/química , Leite/metabolismo , Proteínas do Leite/metabolismo , Tamanho da Partícula , Rúmen/metabolismo , Amido/metabolismo
12.
J Dairy Sci ; 104(2): 1728-1743, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309368

RESUMO

The effect of neutral detergent fiber (NDF) degradability of corn silage in diets containing lower and higher NDF concentrations on lactational performance, nutrient digestibility, and ruminal characteristics in lactating Holstein cows was measured. Eight ruminally cannulated Holstein cows averaging 91 ± 4 (standard error) days in milk were used in a replicated 4 × 4 Latin square design with 21-d periods (7-d collection periods). Dietary treatments were formulated to contain either conventional (CON; 48.6% 24-h NDF degradability; NDFD) or brown midrib-3 (BM3; 61.1% 24-h NDFD) corn silage and either lower NDF (LNDF) or higher NDF (HNDF) concentration (32.0 and 35.8% of ration dry matter, DM) by adjusting the dietary forage content (52 and 67% forage, DM basis). The dietary treatments were (1) CON-LNDF, (2) CON-HNDF, (3) BM3-LNDF, and (4) BM3-HNDF. Data were analyzed as a factorial arrangement of diets within a replicated Latin square design with the MIXED procedure of SAS (SAS Institute Inc., Cary, NC) with fixed effects of NDFD, NDF, NDFD × NDF, period(square), and square. Cow within square was the random effect. Time and its interactions with NDFD and NDF were included in the model when appropriate. An interaction between NDFD and NDF content resulted in the HNDF diet decreasing dry matter intake (DMI) with CON corn silage but not with BM3 silage. Cows fed the BM3 corn silage had higher DMI than cows fed the CON corn silage, whereas cows fed the HNDF diet consumed less DM than cows fed the LNDF diet. Cows fed the BM3 diets had greater energy-corrected milk yield, higher milk true protein content, and lower milk urea nitrogen concentration than cows fed CON diets. Additionally, cows fed the BM3 diets had greater total-tract digestibility of organic matter and NDF than cows fed the CON diets. Compared with CON diets, the BMR diets accelerated ruminal NDF turnover. When incorporated into higher NDF diets, corn silage with greater in vitro 24-h NDFD and lower undegradable NDF at 240 h of in vitro fermentation (uNDF240) allowed for greater DMI intake than CON. In contrast, for lower NDF diets, NDFD of corn silage did not affect DMI, which suggests that a threshold level of inclusion of higher NDFD corn silage is necessary to observe enhanced lactational performance. Results suggest that there is a maximum gut fill of dietary uNDF240 and that higher NDFD corn silage can be fed at greater dietary concentrations.


Assuntos
Bovinos/fisiologia , Fibras na Dieta/metabolismo , Digestão/fisiologia , Lactação/fisiologia , Rúmen/metabolismo , Zea mays/metabolismo , Animais , Dieta/veterinária , Fibras na Dieta/administração & dosagem , Ingestão de Alimentos , Feminino , Fermentação , Leite/química , Proteínas do Leite/metabolismo , Silagem/análise , Zea mays/química
13.
J Dairy Sci ; 104(2): 1645-1659, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309369

RESUMO

The aim of this study was to evaluate the short- and long-term effects of initial serum total protein (STP) concentration, average starter feed intake (SI) during the last week of the preweaning period, and average daily gain (ADG) on the growth, fertility, and performance of Holstein heifers during their first lactation. Eighty-four female Holstein dairy calves were weaned at d 56 of age and then the study continued until the end of the first lactation. Growth performance, including body weight, ADG, withers height, and its change were analyzed monthly from 3 to 450 d of life, and reproduction data and performance in the first lactation of primiparous dairy heifers over a 4-yr period (2015 to 2019) were recorded. In the first 24 h of life, calves received 4 L of colostrum (<2 h and <12 h after birth); on d 2 and 3: 2 feedings/d of 2 L of transition milk; from d 4 to 49: 6 L/d of milk replacer (150 g of powder/L as-fed) in 3 feedings; and from d 50 to 56: 2 L/d of milk replacer in 1 feeding. The calves were fed pelleted starter feed from d 4 to 56, and after that from 8 wk until 3 mo of age, a dry total mixed ration with an 85:15 ratio of weaning pelleted starter to straw. From 3 to 7 mo and from 8 mo of age to calving, the total mixed ration contained 16.9% and ~14.0% crude protein, respectively, on a dry matter basis and ~2.40 Mcal of metabolizable energy/kg on a dry matter basis. The results of the current study showed that the initial STP concentration of primiparous dairy heifers was associated with improved growth performance, especially greater body weight and withers height. In addition, with increasing levels of initial STP concentration, age at first estrus, artificial insemination (AI) service, pregnancy, and calving was decreased by 16, 18, 25, and 25 d, respectively. Initial STP concentration was positively correlated with milk production and increased total milk yield and yield of energy-corrected milk by about 1,558 kg and 1,149 kg during first lactation. Calves with higher average starter feed intake during the last week of the preweaning period had better growth performance, which in turn was positively associated with fertility parameters, accelerated first estrus (by 17 d), and reduced age at AI service (by 13 d). Preweaning ADG was favorably associated with fertility performance of heifers, with faster occurrence of first estrus and a reduction in age at AI service, pregnancy, and calving. Also, increasing preweaning ADG increased milk yield, energy-corrected milk, and 4% fat-corrected milk at 305 DIM by about 829, 754, and 763 kg at first lactation of primiparous heifers. These results indicate that in the rearing period, particular attention should be paid to the initial STP concentration, average SI during the last week of this period, and rearing ADG to increase growth, fertility, and performance in the first lactation of primiparous dairy heifers.


Assuntos
Proteínas Sanguíneas/análise , Bovinos/fisiologia , Ingestão de Alimentos/fisiologia , Ganho de Peso/fisiologia , Ração Animal/análise , Animais , Indústria de Laticínios/métodos , Dieta/veterinária , Metabolismo Energético , Feminino , Fertilidade , Inseminação Artificial/veterinária , Lactação/fisiologia , Leite/metabolismo , Paridade , Gravidez , Desmame
14.
J Dairy Sci ; 104(2): 1680-1695, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309371

RESUMO

Our objective was to determine if methods for preparing total mixed ration [TMR; horizontal paddle mixer with knives (PK) vs. vertical auger (VA) mixer] would alter the physical form of the TMR and affect utilization of diets with increasing amounts of modified wet distillers grains with solubles (MWDGS). Holstein cows (n = 24 with 12 ruminally cannulated; 144 d in milk ± 31 d at start) were used in a split-plot design with mixer type as the whole plot and MWDGS concentrations as subplots in a replicated 3 × 3 Latin square arrangement with 35-d periods. Inclusion rates of MWDGS were 10, 20, and 30% of dietary dry matter, primarily replacing corn, soybean meal, soyhulls, and whole cottonseed. Feed dry matter intake (DMI) was less for PK (23.8 kg/d) than for VA (25.7 kg/d), but was unaffected by MWDGS concentration. Milk production did not differ by concentration of MWDGS or by interaction of MWDGS × mixer. Milk fat percentage declined with increasing MWDGS but the interaction between mixer and MWDGS showed that decreases were larger with VA mixing. Cows fed the diet containing 30% MWDGS mixed with PK averaged 3.45% (1.24 kg/d) milk fat, whereas cows fed the same diet mixed with VA averaged 2.81% (1.10 kg/d) fat. Concentrations of trans-10,cis-12 C18:2 in milk fat likely explain the differences observed in milk fat yield; the concentration of trans-10,cis-12 C18:2 increased as MWDGS was increased and the MWDGS × mixer interaction showed that VA had greater concentrations. Greater mean particle size and increased variation in particle size with VA may partially explain differences in milk fat via increased sorting that allowed for an altered rumen environment and favored alternative biohydrogenation pathways. Feed conversion efficiency (FCE; energy-corrected milk/DMI) decreased linearly as MWDGS increased, but FCE tended to be maintained when higher MWDGS diets were mixed using PK rather than VA. Ruminal pH and ammonia concentration decreased linearly as MWDGS increased. The PK mixer resulted in greater FCE when higher amounts of MWDGS were fed, primarily because milk fat content and yield were not as depressed and DMI was lower at similar milk yields.


Assuntos
Bovinos/fisiologia , Dieta/veterinária , Grão Comestível , Manipulação de Alimentos/métodos , Lactação/fisiologia , Rúmen/metabolismo , Amônia/análise , Ração Animal/análise , Animais , Feminino , Concentração de Íons de Hidrogênio , Lipídeos/análise , Leite/química , Tamanho da Partícula , Rúmen/química , Soja , Zea mays
15.
J Dairy Sci ; 104(2): 1744-1758, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309378

RESUMO

The objective of this study was to differentiate the effects of acute heat stress (HS) from those of decreased dry matter intake (DMI) during the prepartum period on metabolism, colostrum, and subsequent production of dairy cows. Holstein dairy cows (n = 30) with similar parity and body weight were randomly assigned to 1 of 3 treatments on 45 d before calving: (1) cooled (CL, n = 10) conditions with ad libitum feed intake, (2) HS conditions with ad libitum feed intake (n = 10), and (3) pair-fed cooled (CLPF, n = 10) with reduced DMI similar to the HS group while housed under cooled conditions. The reduction in the amount of feed offered to the CLPF cows was calculated daily as the percentage decrease from the average DMI of HS cows relative to the CL cows. For CLPF and CL cows, barns provided shade, sprinklers, and fans, whereas the HS cows were provided only with shade. Cows in all groups received individually the same total mixed ration. Cows were dried off 60 d before the expected calving. Cows in the HS group and, by design, the CLPF cows had reduced DMI (~20%) during the experiment. Heat stress decreased gestation length, first colostrum yield, and calf birth weight compared with CL and CLPF cows. Milk yield decreased 21% (5 kg) in the HS and 8% (2 kg) in CLPF cows, indicating that reduced feed intake during late gestation accounted for 60% of the total reduced milk yield. The CLPF cows exhibited an elevated NEFA concentration compared with the CL and HS cows. The HS cows had a greater mRNA abundance of HSP70 in the peripheral blood leukocytes at 21 d prepartum compared with the other groups. At calving, the mRNA abundance of HSP70 was greater in HS cows, followed by CLPF, compared with the CL cows. In conclusion, HS during the late gestation period caused metabolism and production differences, which were only partially attributed to reduced feed intake in dairy cows.


Assuntos
Bovinos/fisiologia , Colostro/fisiologia , Ingestão de Alimentos/fisiologia , Resposta ao Choque Térmico/fisiologia , Lactação/fisiologia , Parto/fisiologia , Ar Condicionado , Animais , Peso ao Nascer , Feminino , Idade Gestacional , Abrigo para Animais , Leite/metabolismo , Gravidez , Temperatura
16.
J Dairy Sci ; 104(2): 1887-1899, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309358

RESUMO

Shortening or omitting the dry period to improve the energy balance in early lactation have the trade-offs of reduction in milk production and loss of opportunity for dry-cow therapy (DCT; i.e., intramammary antibiotic use at dry-off). Customized dry-period strategies (i.e., deciding upon DCT and dry-period length per cow) could mitigate negative effects of short or no dry periods on milk production and udder health and simultaneously retain benefits from improved energy balance and fertility. In this study, we evaluated 3 decision trees to customize dry-period strategies for individual cows. In the control tree (CT), all cows had a 60-d dry period, with DCT if somatic cell count (SCC) was >150,000 cells/mL before dry-off. In decision tree 1 (T1), parity 1 and parity >1 cows were assigned DCT if SCC was ≥150,000 cells/mL and SCC ≥50,000 cells/mL, respectively; whereas in decision tree 2 (T2), the threshold for DCT was SCC ≥200,000 cells/mL for all animals. In T1 and T2, cows with DCT were assigned a 60-d dry period, whereas cows without DCT were assigned a 30-d or 0-d dry period if their milk production remained >12 kg/d at 67 and 37 d before calving, respectively. Cows were monitored from 8 wk before to 14 wk after calving. Milk production and composition, SCC, body condition score, body weight, and occurrence of treatment for disease (related to calving and start of lactation) were compared between CT (n = 61 cows), T1 (n = 59 cows), and T2 (n = 63 cows). Effects of decision trees (CT, T1, T2) and of dry-period strategies (60-d dry with or without antibiotics, 30-d dry, or 0-d dry) on measured variables were analyzed separately with mixed models, effects on udder-health status with a logistic regression, and occurrence of treatment for diseases with a Pearson chi-squared test. In T1, 36% of cows qualified for 30-d and 2% for 0-d dry periods, whereas in T2 this was 51% and 30% for 30-d and 0-d dry periods, respectively. Compared with CT, cows in T1 and T2 on average produced more milk in the 8 wk before calving (0.2 vs. 3.9 vs. 7.1 kg/d in CT vs. T1 vs. T2), and less in the 14 wk after calving (40.0 vs. 37.0 vs. 35.2 kg/d in CT vs. T1 vs. T2). There was no difference in udder-health status in the transition period among decision trees. In the first 14 wk after calving, recovery of body weight was greater for T2 than CT and T1. Overall, 30-d and 0-d dry periods reduced milk revenues, but this might be financially compensated by improved cow health with customized dry-period strategies.


Assuntos
Antibacterianos/uso terapêutico , Bovinos/fisiologia , Metabolismo Energético , Leite/metabolismo , Criação de Animais Domésticos , Bem-Estar do Animal , Animais , Peso Corporal/efeitos dos fármacos , Contagem de Células/veterinária , Feminino , Lactação/efeitos dos fármacos , Glândulas Mamárias Animais/fisiologia , Leite/química , Paridade , Gravidez
17.
J Dairy Sci ; 104(2): 1951-1966, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309359

RESUMO

Estimated breeding values of a selection index, production, durability, health, and fertility traits from Canadian Ayrshire, Jersey, and Brown Swiss bulls and cows were used to study genetic selection differentials (GSD). The bulls and cows were born from 1950 and 1960, respectively. The GSD for the 3 Canadian dairy populations were studied along the 4-path selection model: sire-to-bull (SB), dam-to-bull (DB), sire-to-cow (SC), and dam-to-cow (DC) pathways. We also determined the variations in realized GSD due to herd and herd × year of conception in addition to the effects of some environmental factors on realized GSD of the SC and DC paths. The mean realized GSD of the DB were higher than those of other paths and were increasing for lifetime performance index, 305-d milk yield, 305-d fat yield, and 305-d protein yield in all 3 dairy cattle populations. We observed no clear trends in realized GSD for type traits in all 3 dairy cattle breeds except for the apparent increasing trends in realized GSD of mammary system, dairy strength, and feet and legs in the DB and SC paths of the Ayrshire breed. No clear patterns were observed in the realized GSD of daughter fertility in the SB, DB, and SC paths of all dairy cattle breeds. Realized GSD for somatic cell score showed increasing and favorable trends in the 3 most influential selection paths (SB, DB, and SC). Year of conception influenced realized GSD of artificial insemination bulls in Ayrshire, Jersey, and Brown Swiss dairy populations. Selection emphases for the SC path generally increased with time. There was considerable variation among herds in selection pressures applied in the SC and DC pathways but no clear association with housing system or region. This study demonstrates that variations exist among herds of minor dairy cattle breeds in their selection for economically important traits. These variations offer opportunities for further improvements in these populations.


Assuntos
Bovinos/genética , Fertilidade/genética , Fertilização , Leite/metabolismo , Seleção Genética , Animais , Canadá , Bovinos/fisiologia , Feminino , Genética Populacional , Inseminação Artificial/veterinária , Lactação , Masculino , Fenótipo
18.
J Dairy Sci ; 104(2): 1967-1981, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309360

RESUMO

Resilience is the ability of cows to cope with disturbances, such as pathogens or heat waves. To breed for improved resilience, it is important to know whether resilience genetically changes throughout life. Therefore, the aim was to perform a genetic analysis on 2 resilience indicators based on data from 3 periods of the first lactation (d 11-110, 111-210, and 211-340) and the first 3 full lactations, and to estimate genetic correlations with health traits. The resilience indicators were the natural log-transformed variance (LnVar) and lag-1 autocorrelation (rauto) of daily deviations in milk yield from an expected lactation curve. Low LnVar and rauto indicate low variability in daily milk yield and quick recovery, and were expected to indicate good resilience. Data of 200,084 first, 155,784 second, and 89,990 third lactations were used. Heritabilities were similar based on different lactation periods (0.12-0.15 for LnVar, 0.05-0.06 for rauto). However, the heritabilities of the resilience indicators based on full first lactation were higher than those based on lactation periods (0.20 for LnVar, 0.08 for rauto), due to lower residual variances. Heritabilities decreased from 0.20 in full lactation 1 to 0.19 in full lactation 3 for LnVar and from 0.08 to 0.06 for rauto. For LnVar, as well as for rauto, the strongest genetic correlation between lactation periods was between period 2 and 3 (0.97 for LnVar, 0.96 for rauto) and the weakest between period 1 and 3 (0.81 for LnVar, 0.65 for rauto). Similarly, for both traits the genetic correlation between full lactations was strongest between lactations 2 and 3 (0.99 for LnVar, 0.95 for rauto) and weakest between lactations 1 and 3 (0.91 for LnVar, 0.71 for rauto). For LnVar, genetic correlations with resilience-related traits, such as udder health, ketosis, and longevity, adjusted for correlations with milk yield, were almost always favorable (-0.59 to 0.02). In most cases these genetic correlations were stronger based on full lactations than on lactation periods. Genetic correlations were similar across full lactations, but the correlation with udder health increased substantially from -0.31 in lactation 1 to -0.51 in lactation 3. For rauto, genetic correlations with resilience-related traits were always favorable in lactation period 1 and in most full lactations, but not in the other lactation periods. However, correlations were weak (-0.27 to 0.15). Therefore, as a resilience indicator for breeding, LnVar is preferred over rauto. A multitrait index based on estimated breeding values for LnVar in lactations 1, 2, and 3 is recommended to improve resilience throughout the lifetime of a cow.


Assuntos
Bovinos/genética , Lactação/genética , Leite/metabolismo , Animais , Bovinos/fisiologia , Feminino , Testes Genéticos/veterinária , Longevidade , Glândulas Mamárias Animais/fisiologia , Fenótipo
19.
J Dairy Sci ; 104(2): 2008-2017, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33358169

RESUMO

Breeding objectives in the dairy industry have shifted from being solely focused on production to including fertility, animal health, and environmental impact. Increased serum concentrations of candidate biomarkers of health and fertility, such as ß-hydroxybutyric acid (BHB), fatty acids, and urea are difficult and costly to measure, and thus limit the number of records. Accurate genomic prediction requires a large reference population. The inclusion of milk mid-infrared (MIR) spectroscopic predictions of biomarkers may increase genomic prediction accuracy of these traits. Our objectives were to (1) estimate the heritability of, and genetic correlations between, selected serum biomarkers and their respective MIR predictions, and (2) evaluate genomic prediction accuracies of either only measured serum traits, or serum traits plus MIR-predicted traits. The MIR-predicted traits were either fitted in a single trait model, assuming the measured trait and predicted trait were the same trait, or in a multitrait model, where measured and predicted trait were assumed to be correlated traits. We performed all analyses using relationship matrices constructed from pedigree (A matrix), genotypes (G matrix), or both pedigree and genotypes (H matrix). Our data set comprised up to 2,198 and 9,657 Holstein cows with records for serum biomarkers and MIR-predicted traits, respectively. Heritabilities of measured serum traits ranged from 0.04 to 0.07 for BHB, from 0.13 to 0.21 for fatty acids, and from 0.10 to 0.12 for urea. Heritabilities for MIR-predicted traits were not significantly different from those for the measured traits. Genetic correlations between measured traits and MIR-predicted traits were close to 1 for urea. For BHB and fatty acids, genetic correlations were lower and had large standard errors. The inclusion of MIR predicted urea substantially increased prediction accuracy for urea. For BHB, including MIR-predicted BHB reduced the genomic prediction accuracy, whereas for fatty acids, prediction accuracies were similar with either measured fatty acids, MIR-predicted fatty acids, or both. The high genetic correlation between urea and MIR-predicted urea, in combination with the increased prediction accuracy, demonstrated the potential of using MIR-predicted urea for genomic prediction of urea. For BHB and fatty acids, further studies with larger data sets are required to obtain more accurate estimates of genetic correlations.


Assuntos
Biomarcadores/sangue , Bovinos/fisiologia , Fertilidade , Genômica , Leite/química , Espectrofotometria Infravermelho/veterinária , Ácido 3-Hidroxibutírico/sangue , Animais , Bovinos/sangue , Indústria de Laticínios , Ácidos Graxos/sangue , Feminino , Genótipo , Linhagem , Fenótipo , Ureia/sangue
20.
J Dairy Sci ; 104(2): 1928-1950, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33358171

RESUMO

The identification of functional genetic variants and associated candidate genes linked to feed efficiency may help improve selection for feed efficiency in dairy cattle, providing economic and environmental benefits for the dairy industry. This study used RNA-sequencing data obtained from liver tissue from 9 Holstein cows [n = 5 low residual feed intake (RFI), n = 4 high RFI] and 10 Jersey cows (n = 5 low RFI, n = 5 high RFI), which were selected from a single population of 200 animals. Using RNA-sequencing, 3 analyses were performed to identify: (1) variants within low or high RFI Holstein cattle; (2) variants within low or high RFI Jersey cattle; and (3) variants within low or high RFI groups, which are common across both Holstein and Jersey cattle breeds. From each analysis, all variants were filtered for moderate, modifier, or high functional effect, and co-localized quantitative trait loci (QTL) classes, enriched biological processes, and co-localized genes related to these variants, were identified. The overlapping of the resulting genes co-localized with functional SNP from each analysis in both breeds for low or high RFI groups were compared. For the first two analyses, the total number of candidate genes associated with moderate, modifier, or high functional effect variants fixed within low or high RFI groups were 2,810 and 3,390 for Holstein and Jersey breeds, respectively. The major QTL classes co-localized with these variants included milk and reproduction QTL for the Holstein breed, and milk, production, and reproduction QTL for the Jersey breed. For the third analysis, the common variants across both Holstein and Jersey breeds, uniquely fixed within low or high RFI groups were identified, revealing a total of 86,209 and 111,126 functional variants in low and high RFI groups, respectively. Across all 3 analyses for low and high RFI cattle, 12 and 31 co-localized genes were overlapping, respectively. Among the overlapping genes across breeds, 9 were commonly detected in both the low and high RFI groups (INSRR, CSK, DYNC1H1, GAB1, KAT2B, RXRA, SHC1, TRRAP, PIK3CB), which are known to play a key role in the regulation of biological processes that have high metabolic demand and are related to cell growth and regeneration, metabolism, and immune function. The genes identified and their associated functional variants may serve as candidate genetic markers and can be implemented into breeding programs to help improve the selection for feed efficiency in dairy cattle.


Assuntos
Ração Animal/análise , Bovinos/genética , Ingestão de Alimentos , Variação Genética/genética , Leite/metabolismo , Reprodução/genética , Animais , Bovinos/fisiologia , Indústria de Laticínios , Feminino , Fígado/fisiologia , Locos de Características Quantitativas/genética , RNA/genética , Análise de Sequência de RNA/veterinária
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