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ABSTRACT: The preweaning management of dairy calves over the last 30 yr has focused on mortality, early weaning, and rumen development. Recent studies suggest that nutrient intake from milk or milk replacer during the preweaning period alters the phenotypic expression for milk yield. The objective of this study was to investigate the relationship between nutrient intake from milk replacer and pre- and postweaning growth rate with lactation performance in the Cornell dairy herd and a commercial dairy farm. The analysis was conducted using traditional 305-d first-lactation milk yield and residual lactation yield estimates from a test-day model (TDM) to analyze the lactation records over multiple lactations. The overall objective of the calf nutrition program in both herds was to double the birth weight of calves by weaning through increased milk replacer and starter intake. First-lactation 305-d milk yield and residuals from the TDM were generated from 1,244 and 624 heifers from the Cornell herd and from the commercial farm, respectively. The TDM was used to generate lactation residuals after accounting for the effects of test day, calving season, days in milk, days pregnant, lactation number, and year. In addition, lactation residuals were generated for cattle with multiple lactations to determine if the effect of preweaning nutrition could be associated with lifetime milk yield. Factors such as preweaning average daily gain (ADG), energy intake from milk replacer as a multiple of maintenance, and other growth outcomes and management variables were regressed on TDM milk yield data. In the Cornell herd, preweaning ADG, ranged from 0.10 to 1.58 kg, and was significantly correlated with first-lactation yield; for every 1 kg of preweaning ADG, heifers, on average, produced 850 kg more milk during their first lactation and 235 kg more milk for every Mcal of metabolizable energy intake above maintenance. In the commercial herd, for every 1 kg of preweaning ADG, milk yield increased by 1,113 kg in the first lactation and further, every 1 kg of prepubertal ADG was associated with a 3,281 kg increase in first-lactation milk yield. Among the 2 herds, preweaning ADG accounted for 22% of the variation in first-lactation milk yield as analyzed with the TDM. These results indicate that increased growth rate before weaning results in some form of epigenetic programming that is yet to be understood, but has positive effects on lactation milk yield. This analysis identifies nutrition and management of the preweaned calf as major environmental factors influencing the expression of the genetic capacity of the animal for milk yield.
Journal of Dairy Science 02/2012; 95(2):783-93. · 2.56 Impact Factor
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ABSTRACT: Semen processed with procedures intended to permit a flexible thaw method is used to breed millions of cows yearly. One method of thawing straws, the "pocket thaw" is used extensively with semen prepared with these procedures. Published field data is lacking for thaw method comparisons with semen processed to permit flexible-thawing. The objective of the present study was to measure the effect of semen thaw method (warm-water or pocket thaw) over all seasons and its interaction with herds, inseminators, straw package size, and sperm number on conception rate in commercial dairy heifer herds using semen processed with procedures historically optimized for success with flexible-thawing. Professional inseminators performed 11,215 services over a 16-month period in four large herds, achieving a 67.6% conception rate. Thaw method was alternated weekly. Thaw effect on conception status, determined by 70 days non-return rate, was estimated by a generalized linear mixed model. Neither thaw method nor number of sperm per straw significantly affected probability of conception (P=0.658 and 0.769, respectively). No interactions of thaw method with herd, sperm number, season, straw size, and straw size by season were detected (P=0.297, 0.526, 0.365, 0.723, and 0.824, respectively). Bull, herd, inseminator within herd, year, season, and straw size affected conception rate (P=0.002, 0.000, 0.000, 0.000, 0.000, and 0.014, respectively). In conclusion, for semen processed with procedures that permit flexible-thawing, thaw method (pocket thaw versus warm-water thaw) did not affect conception rate under commercial conditions and with routine semen handling methods.
Theriogenology 07/2005; 63(9):2535-49. · 1.96 Impact Factor
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ABSTRACT: Responses of registered Jersey cows to various levels of inbreeding were examined with pedigree data supplied by the American Jersey Cattle Association and test-day production data from 1970 through 1998 obtained from the Animal Breeding Center at Cornell University. Rate of increase in level of inbreeding is accelerating with time, making it more difficult for producers to make matings that avoid the potentially deleterious effects of inbreeding. Production losses caused by inbreeding were significant and curvilinear for all traits studied except somatic cell linear score, with the greatest losses at higher levels of inbreeding. Inbreeding was found to have the greatest effect on production at early ages and early in lactation. Early onset of the deleterious effects of inbreeding resulted in larger net present value losses than if effects of inbreeding occurred later in the life of an animal. Losses were probably enhanced because of the need to freshen animals as early as possible to maximize net present value returns. Survival decreased as level of inbreeding increased and was likely to have a greater negative impact on the financial health of the dairy enterprise than production losses.
Journal of Dairy Science 10/2000; 83(9):2131-8. · 2.56 Impact Factor
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ABSTRACT: Responses of registered Holstein cows to various levels of inbreeding were examined with pedigree data supplied by the Holstein Association USA and test-day production data from 1970 through 1998 obtained from the Animal Breeding Center at Cornell University. Rate of increase in level of inbreeding has been accelerating over time, making it more difficult for producers to make matings that avoid the potentially deleterious effects of inbreeding. Milk production losses per lactation caused by inbreeding were generally 35 kg per percentage inbreeding level >0.01 but increased to 55 kg per percentage inbreeding level from 0.07 to 0.10. Somatic cell score was not affected by level of inbreeding. Inbreeding had the greatest effect on production at ages <22 mo and early in lactation. Early onset of the deleterious effects of inbreeding resulted in larger net present value losses than when effects of inbreeding occurred later. Losses were likely enhanced due to the need to freshen animals as early as possible to maximize net present value returns. Survival decreased as level of inbreeding increased and was likely to have a greater negative impact on the financial health of the dairy enterprise than production losses.
Journal of Dairy Science 08/2000; 83(8):1856-64. · 2.56 Impact Factor
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ABSTRACT: The commercial response to bovine somatotropin was examined in northeast dairy herds from 1990 to 1998 (4-yr preapproval and 4-yr postapproval). With DHI records and Monsanto customer files, a control group (never purchased Posilac) and a bovine somatotropin (bST) group (used on at least 50% of cows) were identified. A total of 340 herds were involved and, over the 8-yr period, there were over 80,000 cows, 200,000 lactations, and 2 million test days. Herd management comparisons demonstrated the response to bST was relatively constant each year of the postapproval period. Assuming 100% of cows were supplemented, response to bST over a 305-d lactation equaled 894 kg of milk, 27 kg of milk fat, and 31 kg of milk protein. Comparisons of lactation curves were used to identify where the bST response occurred in the lactation cycle. Analysis demonstrated the responses in milk, milk fat, and protein yield were minimal in the early phase of lactation, and then gradually increased until reaching a plateau over the last half of the lactation cycle. Persistency of lactation was also improved by bST, indicating the opportunity exists to extend lactation with combined use of bST and altered reproductive management. Average age and days in milk did not differ between control and bST herds. Thus, stayability and herd-life of animals were not altered by bST treatment. Somatic cell count (SCC) linear scores were minimally affected in herds utilizing bST and the pattern of SCC over the lactation cycle was unaffected. Overall bST improved lactation yield and persistency consistently over the 4-yr postapproval period with no effects on cow stayability and herd-life.
Journal of Dairy Science 01/2000; 82(12):2564-73. · 2.56 Impact Factor
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ABSTRACT: The effects of body weight (BW) gain, different sources of protein during the prepubertal period (90 to 320 kg of BW), and the performance of Holstein heifers during their first lactation were studied. Heifers (n = 273) were assigned to one of three dietary energy treatments that were designed to achieve average daily gains of 0.6, 0.8, and 1.0 kg/d. Within each energy treatment, different protein sources (plant protein and urea or both plant and animal proteins) were imposed. Actual average daily gains by heifers on each energy treatment were 0.68, 0.83, and 0.94 kg/d for heifers that were fed diets formulated for average daily gains of 0.6, 0.8, and 1.0 kg/d, respectively, which allowed the following ages at first calving: 24.5, 22.0, and 21.3 mo. Breeding was initiated when heifers weighed approximately 340 kg. Protein sources did not affect average daily gain or milk yield. Analysis of the preplanned comparisons of actual 305-d and 4% fat-corrected milk yields indicated that yield was significantly reduced for heifers grown at 0.94 kg/d (9387 and 8558 kg, respectively) compared with that of heifers grown at 0.68 kg/d (9873 and 9008 kg, respectively). However, further regression analysis of fat-corrected milk and residual milk from a test day model on prepubertal BW gain only explained 8 and 2% of the variation in milk yield, respectively. Postcalving BW and body condition score were different among treatments. Posttreatment factors, such as postcalving BW, accounted for more of the variation in milk yield than did prepubertal BW gain. Prepubertal BW gains, when evaluated on a continuum from 0.5 to 1.1 kg/d, explained little of the variation in milk yield; therefore, BW gain during the prepubertal period did not significantly affect milk yield during first lactation.
Journal of Dairy Science 02/1998; 81(2):527-38. · 2.56 Impact Factor
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ABSTRACT: Prediction of daily yield from single a.m. or p.m. milkings requires factors that are the reciprocal of the proportion of total yield expected from single milkings given the milking interval. Further adjustments to estimated milk yield account for DIM. Factors used by the Cornell Dairy Records Processing Lab were estimated from data collected from August 1983 to November 1984. These factors appear to be biased. Inconsistent estimates of daily yield were observed monthly. New factors were developed using recent data. Factors from a.m. milkings for milk and protein yield were smaller than those currently in use. The reverse was true for fat yield. Covariants for DIM were larger than those currently used. Differences were observed when factors using data with known and assumed milking intervals were compared. Factors for a.m. milkings with known intervals were smaller than those from p.m. milkings with the same known intervals. Use of covariants for DIM were compared with covariants for single milk yield. The latter explained more variation in yield. Factors were tested on independent data. New factors with covariants for single milk yield performed best for estimation of total daily yield.
Journal of Dairy Science 02/1995; 78(1):221-35. · 2.56 Impact Factor
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ABSTRACT: Genetic parameters were estimated for yields and percentages of milk, fat, and protein for registered Italian Brown Swiss cows. Data were 72,690 mature equivalent 305-d first lactation yields split by herd average milk into four files. An expectation-maximization REML algorithm was used on a multiple-trait model with equal design matrices for fixed and random effects. Data were preadjusted for geographical area, age-month of calving, and days open. The model included herd-year and sire genetic group as fixed effects and sires as random effects. Estimates of heritability were .28, .30, .26, .42, and .34 for milk, fat, and protein yields, and fat and protein percentages, respectively. Genetic correlations of milk yield and milk component percentages were negative, as expected. Correlation of protein yield and protein percentage was null. Results show an increasing tend of variance components from low to high herd yields, indicating that dispersion of yield about the mean increases as average yield increases. Relative differences among environmental components were larger than those among genetic components, yielding larger estimates of heritability in herds with lower yield. Estimates of heritability for milk from low to high herd yields were .42, .38, .35, and .33.
Journal of Dairy Science 12/1993; 76(11):3594-600. · 2.56 Impact Factor
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ABSTRACT: Test day models were used to estimate lactation curves for milk, fat, protein, fat percentage, and protein percentage and to study the influence of age, season, and herd productivity on Holstein lactation curves. Random effects of lactation within herd and fixed effects of herd test date were absorbed. Fixed effects of cow's age on test day and either DIM (57 divisions) by parity (1, 2, greater than or equal to 3) class or season of calving (winter or summer) by DIM by parity class were estimated. Lactation curves for yield traits derived from DIM solutions were flatter for first versus later lactation, even without addition of age effects. Differences between lactation curves for the two seasons were slight, suggesting that most observed seasonal differences are caused by seasonal productivity accounted for by herd test date effects. At peak, winter calving cows yielded slightly more milk of similar fat percentage but of lower protein percentage than those calving in summer. Data were also partitioned into nine subsets based on rolling herd milk and fat percentage. Lactation curves for yield traits, but not percentage traits, varied with rolling herd milk. Lactation curves for fat yield and percentage varied with rolling herd fat percentage.
Journal of Dairy Science 07/1992; 75(6):1691-700. · 2.56 Impact Factor
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ABSTRACT: The commercial response to bovine somatotropin was examined in northeast dairy herds from 1990 to 1998 (4-yr preapproval and 4-yr postapproval). With DHI records and Monsanto customer files, a control group (never purchased Posilac) and a bovine somatotropin (bST) group (used on at least 50% of cows) were identified. A total of 340 herds were involved and, over the 8-yr period, there were over 80,000 cows, 200,000 lactations, and 2 million test days. Herd management comparisons demonstrated the response to bST was relatively constant each year of the postapproval period. Assuming 100% of cows were supplemented, response to bST over a 305-d lactation equaled 894 kg of milk, 27 kg of milk fat, and 31 kg of milk protein. Comparisons of lactation curves were used to identify where the bST response occurred in the lactation cycle. Analysis demonstrated the responses in milk, milk fat, and protein yield were minimal in the early phase of lactation, and then gradually increased until reaching a plateau over the last half of the lactation cycle. Persistency of lactation was also improved by bST, indicating the opportunity exists to extend lactation with combined use of bST and altered reproductive management. Average age and days in milk did not differ between control and bST herds. Thus, stayability and herd-life of animals were not altered by bST treatment. Somatic cell count (SCC) linear scores were minimally affected in herds utilizing bST and the pattern of SCC over the lactation cycle was unaffected. Overall bST improved lactation yield and persistency consistently over the 4-yr postapproval period with no effects on cow stayability and herd-life.
Journal of Dairy Science.
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ABSTRACT: The primary advantages of reducing age at first calving (AFC) include reducing rearing costs as well as reducing time in which the heifer is only a capital drain on farm resources. The primary disadvantage of reducing AFC is that it is frequently associated with a reduction in first-lactation milk yield. Despite this reduction in first-lactation milk yield, production per year of herd life is typically increased by reduced AFC. Furthermore, although the first lactation yield may be influenced by AFC, future lactations are decidedly not. In addition, stayability and health of cows are not influenced by reduced AFC as long as heifers freshen at an adequate weight. Most analyses indicate that the financial advantage afforded from heifers that freshen at a low AFC seems to at the least offset any milk lost during the first lactation. Furthermore, when the time value of money is considered in this analysis, a reduced AFC (~22 months) seems likely to represent a more fiscally sound management decision. When applying these ideas on the farm, a properly managed feeding and breeding program should permit a firstlactation cow to weigh ~1,210 lb after freshening at 22 months of age. The National Research Council recommends a postpartum weight equal to 82% of her mature body weight. This can be achieved with a maximal prepubertal average daily gain (ADG) of 2 lb/day when a traditional preweaning program is employed or 1.8 lb/day when an intensified preweaning program is employed. Because of the well defined link between inadequate body weight at calving and increased mortality and morbidity in first-lactation cows, achieving this target post-calving body weight is of critical importance.
