Francisco Gerardo Véliz

Effect of lactation number, year, and season of initiation of lactation on milk yield of cows hormonally induced into lactation and treated with recombinant bovine somatotropin.

Records representing data from 1,500 barren Holstein cows over an 8-yr period from a large commercial dairy farm in northern Mexico were analyzed to determine the effects of lactation number and season and year of initiation of lactation on milk production of cows induced hormonally into lactation and treated with recombinant bovine somatotropin (rbST) throughout lactation. Peak and 305-d milk yields were also assessed as predictors of total milk yield in cows induced into lactation. A significant quadratic relationship was found between 305-d milk yield and number of lactation [7,607±145 and 9,548±181 kg for first- and ≥6-lactation cows, respectively; mean ± standard error of the mean (SEM)] with the highest production occurring in the fifth lactation. Total milk yields of cows with ≤2 lactations were approximately 4,500 kg less than milk yields of adult cows (the overall average ± standard milk yield was 13,544±5,491 kg per lactation and the average lactation length was 454±154 d). Moreover, 305-d milk production was depressed in cows induced into lactation in spring (8,804±153 kg; mean ± SEM) and summer (8,724±163 kg) than in fall (9,079±151 kg) and winter (9,085±143 kg). Partial regression coefficients for 305-d milk yield and peak milk yield indicated an increment of 157 kg of milk per lactation per 1-kg increase in peak milk yield (r(2)=0.69). Neither peak milk yield (r(2)=0.18) nor 305-d milk yield (r(2)=0.29) was accurate for predicting total milk yield per lactation. Year, parity, and season effects had significant influence on milk yield of cows induced into lactation and treated with rbST throughout lactation, and peak milk yield can assist in the prediction of 305-d milk yield but not total milk yield. This study also showed that hormonal induction of lactation in barren high-yielding cows is a reliable, practical, and affordable technique in countries where rbST treatment and prolonged steroid administration of dairy cows are legally permitted.

Factors influencing pregnancy per artificial insemination in repeat-breeder cows induced to ovulate with a CIDR-based protocol.

The aim of this study was to determine, using multiple logistic models, factors affecting pregnancy per AI (P/AI) following fixed-time artificial insemination (FTAI) in repeat breeders cows (RBC) treated with rbST throughout lactation. 498 RBC received a CIDR device and 100μg of GnRH on day 0. CIDR removal and PGF(2α) (25mg) treatment were done concurrently on day 7. Estradiol benzoate (EB, 1mg) was injected on day 8 and GnRH on day 9; cows were inseminated 16-20h later. Cows with an average milk protein <3% were 43% more likely (P<0.05) to become pregnant at FTAI than cows with milk protein ≥3%. Cows with <6 services had significantly increased chances of becoming pregnant than cows with ≥6 services at FTAI (P/AI 36 vs. 27%; P<0.05). CIDR-treated cows with less than three lactations were 1.7 times more likely (P/AI 35 vs. 21%; P<0.05) to become pregnant than cows in third or greater lactation. Cows with peak milk yields lower than 55kg were 1.5 times more likely to get pregnant than cows with peak milk yields greater than 55kg (P/AI 37 vs. 28%; P<0.05). P/AI was lower (30 vs. 35%; P<0.01) for cows with dry periods <62 days than cows with dry periods ≥62 days. Cows subjected to FTAI with a temperature-humidity index (THI) <76 were 45% more likely (P<0.05) to become pregnant than cows inseminated at a THI≥76. It was concluded that an acceptable proportion (32%) of RBC can become pregnant with the protocol used in the present study. Also, subfertility in CIDR-treated cows was associated with high peak yields, high milk protein, increased service, increased lactation, high THI at AI and short dry periods.

Milk Yield of Holstein Cows Induced into Lactation Twice Consecutively and Lactation Curve Models Fitted to Artificial Lactations

Nineteen multiparous barren Holstein cows were subjected to an induction of lactation protocol for 21 d administering estradiol cypionate (2 mg kg−1 of body weight (BW) d−1, on day 1 to 14), progesterone (0.10 mg kg−1 of BW, on day 1 to 7), flumethasone (0.03 mg kg−1 of BW, on day 18 to 20) and recombinant bovine somatotropin (rbST; 500 mg per cow, on day 1, 6, 16 and 21). At the end of lactation and with a minimum of a 2-mon dry period, the same cows were again hormonally induced into lactation. Cows in both lactations were not artificially inseminated, they were milked 3 times daily and received rbST throughout lactation. Mean accumulated milk yield at 305 d in milk (DIM) did not differ between the first and second induced lactations ((9 710 ±1 728) vs. (9 309±2 150) kg; mean±SD). Total milk yield ((12 707±3 406) vs. (12 306±4 218) kg; mean±SD) and lactation length ((405±100) vs. (410±91) d; mean±SD) were not different between the first and second induced lactations. In a second study, 15 empirical models including exponential, power law, yield-density, sigmoidal and miscellaneous models were compared for their suitability by modeling 12-mon (n=334), 18-mon (n=164) and 29-mon (n=22) lactation cycles of Holsteins cows induced into lactation and treated with rbST throughout the lactation. Hoerl (Y= ab1/xxc), Wood (Y=axb exp(cx)) and Dhanoa (Y=ax(bc)exp(cx)) models were equally suitable to describe 12-mon lactations. An exponential model with five parameters (Y=exp(a+bx+cd2+e/x)) showed the best fit for milk yield for 18-mon lactations. The rational model (Y=a+bx/1+cx+dx2) was found to produce the closest fit for 29-mon lactations. It was concluded that, with the protocol used in the present study, multiparous cows respond favorably to a second cycle of induced lactation, with milk yield similar to that experienced during the first cycle. Thus, dairy producers might be able to lengthen the productive life of infertile high producing cows with a renewal of artificial lactation, which would imply an overall reduction in voluntary culling of cows. Also, various equations used to describe the lactation curves demonstrated the potential for fitting monthly milk records of Holstein cows with prolonged lactations and induced hormonally into lactation.

The Expression of Birth Weight is Modulated by the Breeding Season in a Goat Model

The Expression of Birth Weight is Modulated by the Breeding Season in a Goat Model Birth weight (BW) is frequently considered as an indicator to detect possible restrictions of intrauterine development. This study evaluated the effect of breeding season (BS) across year: spring (SP), summer (SM), fall (FL) and winter (WT) upon the expression of BW. This meta-analysis considered records (n = 1,084) collected from a commercial herd kept under intensive conditions (22° NL, 1,835 m). The definitive statistical model for BW analysis considered the independent variables kidding year, (KY), genetic group (GT), litter size (LS), gender (GN), breeding season (BS), kidding season (KS) plus the interactions (KY*GT) and (GN*BS). BW expression was affected (P<0.05) by KY, GN, LS, KS, and KY*GT. Interestingly, while BW expression was not affected (P>0.05) by kidding season, it was affected (P<0.05) by breeding season. The highest and lowest BW values were observed in SP and WN (3.34 vs. 3.10 kg; P<0.05), respectively. This physiological scenario could be the result of embryonic-fetal adaptive responses representing homeostatic adaptations due to alterations including doe nutritional status, available quantity and quality of food to both the embryo and the fetus as well as to a changing external environment. Wpływ sezonu rozpłodowego na ekspresję urodzeniowej masy ciała w modelu kozim Masa ciała przy urodzeniu (BW) często służy jako wskaźnik do wykrywania możliwych ograniczeń w wewnątrzmacicznym rozwoju płodu. W badaniach tych oceniano wpływ sezonu rozpłodowego (BS) w ciągu roku: wiosna (SP), lato (SM), jesień (FL), zima (WT) na ekspresję BW. W metaanalizie wzięto pod uwagę dane (n = 1084) zebrane z komercyjnego stada utrzymywanego w intensywnych warunkach (22° szer. geogr. półn., 1835 m n.p.m.). Ostateczny model statystyczny dla analizy BW uwzględniał następujące zmienne niezależne: rok wykotu (KY), grupę genetyczną (GT), wielkość miotu (LS), płeć (GN), sezon rozpłodowy (BS), sezon wykotów (KS) z interakcjami (KY*GT) i (GN*BS). Na ekspresję BW (P<0,05) wpłynęły KY, GN, LS, KS i KY*GT. Co ciekawe, na ekspresję BW (P>0,05) wpływał nie sezon wykotów, lecz sezon rozpłodowy (P<0,05). Najwyższe i najniższe wartości BW zaobserwowano na wiosnę i w zimie (3,34 vs. 3,10 kg; P<0,05). Ten fizjologiczny scenariusz mógł być rezultatem odpowiedzi adaptacyjnych zarodka/płodu, będących homeostatycznymi adaptacjami spowodowanymi zmianami w stanie odżywienia samicy, ilości i jakości pożywienia dostępnego zarówno dla zarodka, jak i płodu oraz zmiennym środowiskiem zewnętrznym.

Conception rate of artificially inseminated Holstein cows affected by cloudy vaginal mucus, under intense heat conditions

The objective of this work was to obtain prevalence estimates of cloudy vaginal mucus in artificially inseminated Holstein cows raised under intense heat, in order to assess the effect of meteorological conditions on its occurrence during estrus and to determine its effect on conception rate. In a first study, an association was established between the occurrence of cloudy vaginal mucus during estrus and the conception rate of inseminated cows (18,620 services), raised under intense heat (mean annual temperature of 22°C), at highly technified farms, in the arid region of northern Mexico. In a second study, data from these large dairy operations were used to assess the effect of meteorological conditions throughout the year on the occurrence of cloudy vaginal mucus during artificial insemination (76,899 estruses). The overall rate of estruses with cloudy vaginal mucus was 21.4% (16,470/76,899; 95% confidence interval = 21.1-21.7%). The conception rate of cows with clean vaginal mucus was higher than that of cows with abnormal mucus (30.6 vs. 22%). Prevalence of estruses with cloudy vaginal mucus was strongly dependent on high ambient temperature and markedly higher in May and June. Acceptable conception rates in high milk-yielding Holstein cows can only be obtained with cows showing clear and translucid mucus at artificial insemination.

The effects of four protocols for the treatment of retained placenta on reproduction performance and milk yield in Holstein cows

MELLADO M. Autonomous Agrarian University Antonio Narro, Department of Animal Nutrition, Saltillo SOLANO R. Autonomous Agrarian University Antonio Narro, Department of Veterinary Science VELIZ F. Autonomous Agrarian University Antonio Narro, Department of Veterinary Science DE SANTIAGO A. Autonomous Agrarian University Antonio Narro, Department of Veterinary Science GAYTAN L. Autonomous Agrarian University Antonio Narro, Department of Animal Nutrition GARCIA J. Autonomous Agrarian University Antonio Narro, Department of Animal Nutrition http://dx.doi.org/10.12681/jhvms.16030

Effect of quality of colostrum on health, growth and immunoglobulin G concentration in Holstein calves in a hot environment

Abstract The aim of this study was to determine the effect of ingestion of pasteurized and subsequently frozen–thawed pooled colostrum (≥50 mg Ig/mL) with different bacterial counts and immunoglobulin concentration (IgC) on the occurrence of diarrhea and pneumonia in 306 neonatal Holstein calves in a hot environment. Calves were assigned to be fed colostrum with total bacterial counts (TBC) lower or greater than 100 000 colony‐forming units (cfu)/mL, total coliform counts (TCC) greater or lower than 10 000 cfu/mL, and IgC lower or higher than 85 mg Ig/mL. Calves fed colostrum with TBC ≥100 000 cfu/mL were more likely (risk ratio 1.34, confidence interval 1.05–1.71; P < 0.05) to present pneumonia than calves receiving colostrum with lower TBC (incidence 53.2 vs. 39.8%). Calves fed colostrum with high TCC had increased chances of suffering pneumonia (51.4 vs. 42.1%; P < 0.05) than calves fed colostrum with lower TCC. Calves fed colostrum with ≥85 mg Ig/mL tended to present higher daily weight gain (505 ± 113 vs. 484 ± 126 g; P = 0.09). TBC and TCC in colostrum did not influence the incidence rate of diarrhea. It was concluded that under the conditions of the present study, heavy contamination of on‐farm pasteurized frozen–thawed colostrum is seemingly unavoidable and this contamination poses a threat for pneumonia, but not for diarrhea.

Milk production, kidding interval and kid growth of indigenous goats of southern Mexico

espanolResumen: Se registro la produccion de leche, el intervalo entre partos y el crecimiento de los cabritos de cabras criollas del sur de Mexico en pastoreo en bosque tropical. La produccion de leche por lactancia (108 d) fue de 26.9 ± 9.3 kg. La ganancia diaria de peso de los cabritos fue de 67 ± 27 g. La produccion diaria de leche explico que la variacion de la ganancia de peso de los cabritos fuera menor a 1 %. Se concluyo que, debido a la alta inversion energetica en la reproduccion (intervalo entre partos de 195 ± 8 d), el bajo merito genetico para la produccion de leche, su bajo peso corporal (28.7 ± 3.3 kg) y la sub-optima nutricion (solo 6 h diarias de pastoreo), la produccion de leche de las cabras criollas del sur de Mexico es muy pobre, lo cual obliga a sus cabritos a depender del forraje nativo a una edad muy temprana. EnglishAbstract: Milk production, kidding intervals and kid growth were evaluated in 20 multiparous indigenous goats of southern Mexico, grazing on a tropical forest. The association between milk production and kid growth rate was also assessed. The total average milk yield was 26.9 ± 9.3 kg, in lactations of 108 ± 13 d. Average daily weight gain of kids was 67 ± 27 g. Considering the entire lactation, daily milk yield accounted for less than 1 % of the known variation in kid weight gain. It was concluded that, due to the high energy investment in reproduction (mean kidding interval of these goats was 195 ± 8 d), low genetic merit for milk production, low adult body weight (28.7 ± 3.3 kg), and sub-optimum nutrition (6 h daily grazing), the lactation performance of the indigenous goats of southern Mexico was very poor, which forces kids to depend upon native forage at an early age.