Relationship Between Herd Management Practices in the Midwest on Milk and Fat Yield

A dairy management survey was conducted in fall 1985 and spring 1986 in the nine-state area served by the Midstates Dairy Records Processing Center in Ames, IA. The questionnaire, consisting of 57 questions with 254 possible choices, was used to survey dairy producers on DHI testing in Arkansas, Illinois, Iowa, Kansas, Missouri, Nebraska, North Dakota, Oklahoma, and South Dakota. The questions covered housing pactices, milking equipment and practices, feeding regimens, calf rearing and feeding, feed additives, various management categories, and artificial insemination usage. The survey responses were merged with the 1985 year end rolling herd production averages from the processing center. A completely fixed model was fit for all 254 potential responses. The greatest differences among solutions were found in the feeding categories with some of the major differences associated with type of grain and forage fed. Feed additives showed the next largest difference among categories with feed ingredients, such as distillers grain, whole cottonseed, and buffers being associated with higher herd averages. There was a positive association between the length of time a producer had been on DHI and herd averages. Herds using a total AI program had herd averages 506 kg higher than those using only a beef bull

Managing dairy labor (1993)

Reviewed October 1, 1993

G86-819 At What Weight Should Holstein Heifers Freshen?

This guide offers research findings on the appro-priate weights for Holstein heifer freshening and sug-gests producers be aware of economic considerations involved in heifer freshening. Most producers realize that the weight of a heifer at freshening affects the amount of milk produced during the first lactation. Heifers not fed balanced nutritional diets before freshening will not produce at an optimum level since they do not have the body reserves to maintain peak produc-tion. Likewise, a heifer that freshens very heavy will not pro-duce as much as she should because she is too heavy. There must be a break-even point at which a heifer should weigh to optimize first lactation production

G94-1197 The Genetics and Management of Sound Feet and Legs

Sound management of feet and legs in dairy animals affects performance. This guide offers suggestions for good management practices. Two major parameters affect the selection process for any trait: the heritability of the trait as well as the variation associated with the trait

EC87-262 Profitable Midwest Dairy Practices

Extension circular 87-262 is about profitable Midwest dairy practices

Feeding dairy cattle for proper body condition score (1993)

Body condition score is a critical measure of a dairy feeding system's effectiveness. Adequate body fat reserves promote milk production, reproductive efficiency and herd longevity. Excessively fat cows or overly thin cows run much greater risks of metabolic problems, lower milk yield, poor conception rates and dystocia (difficulty calving). Failure to attain proper body condition or rapid changes in body condition score during early lactation may indicate problems in herd health or feeding management. This publication will provide guidance for feeding dairy cattle for proper body condition score.Reviewed October 1993 -- Extension website

EC86-261 Goals for Profitable Dairying

Circular Extension 86-261: This circular is about the goals for profitable dairying, and focuses on the objective as the operator of the dairy farm business, such as establishing strategies that will result in long term profit

Estimation of Relative Economic Value for Herd Life of Dairy Cattle from Profile Equations

Lifetime records of 122,679 cows from 7557 herds, obtained from Mid States Dairy Records Processing Center (Ames, IA), were used to determine net income and net income for the planning horizon. With a planning horizon of five lactations for each cow, the estimated profit from the replacements was credited to each cow not surviving until fifth calving. Net income was defined as lifetime income minus costs. Net income for the planning horizon was defined as net income plus profit from replacements within the planning horizon. Income was from the sale of milk, calves, and culled cows. Costs were included for heifer rearing, feed, labor, and breeding. Longer herd life yielded greater profit for net income and net income for the planning horizon. The rate of increase in profit for longer herd life was reduced for net income for the planning horizon, which accounts for profit from cows replacing a culled cow compared with profit from net income. The relative economic value (phenotypic standard deviation basis) of production to herd life was 0.18:1 for net income and 0.46:1 for net income for the planning horizon. The relative value for herd life was overestimated by about 2.5 times when profit from replacements was not considered. Values for production relative to herd life increased for high milk prices and low feed prices. Lower prices for culled cows in combination with high prices for milk and feed increased the relative economic value of production

CUBIC SPLINES FOR ESTIMATING LACTATION CURVES AND GENETIC PARAMETERS OF FIRST LACTATION HOLSTEIN COWS TREATED WITH BOVINE SOMATOTROPIN

The objective was to estimate genetic parameters and fit lactation curves for cows treated or not treated with bovine somatotropin (bST) and fit specific lactation curves for each animal for both random genetic and permanent environmental components from individual test-day milk, fat, and protein yields with a cubic spline model. A total of 70,752 test-day observations for first lactation Holstein cows recorded as treated bST and 73,387 test-day observations for untreated cows that calved between 1994 and early 1999 were obtained from Dairy Records Management Systems in Raleigh, North Carolina. The model included herd test-day, age at first calving, bST treatment, and days in lactation when test-day yield was recorded as fixed effects. Cubic splines were fitted for the overall lactation curve, additive genetic effects, and permanent environmental effects. The cubic splines used five predetermined intervals between days 0, 50, 135,220, and 305. Estimates of the (co)variances for the random components of cubic spline model with five knots were obtained with REML. Estimates of genetic parameters were calculated for the average test day model within each of the ten 30-d test day intervals. The estimates of heritability for milk, fat, and protein yields ranged from 0.09 to 0.15, 0.06 to 0.10, and 0.08 to 0.15 for test-day one to test-day ten. Estimates of genetic correlations between testdays ranged from 0.99 to 0.34 for milk yield, 0.99 to 0.49 for fat yield, and 0.99 to 0.36 for protein yield. Estimates of phenotypic correlations between test-days ranged from 0.67 to 0.27 for milk yield, 0.52 to 0.16 for fat yield, and 0.60 to 0.19 for protein yield. Differences between bST treated and untreated cows of 2 to 4 kg and 0.10 to 0.16 kg for milk and fat yields (smaller for protein yield) at day 90 were maintained until about day 305 of lactation

Genetic Parameters and Responses of Linear Type, Yield Traits, and Somatic Cell Scores to Divergent Selection for Predicted Transmitting Ability for Type in Holsteins

The objective was to examine the direct and correlated responses of linear type, yield traits, and somatic cell scores (SCS) to divergent selection for predicted transmitting ability for type (PTAT) in Holsteins, while maintaining selection for yield traits across lines. For four generations, one-half of the University of Nebraska research Holstein herd was bred to Holstein sires with PTAT -1.50 and the other half to sires with PTAT - 1.25, with nearly equal predicted transmitting abilities for yield traits for both groups. Estimates of genetic and residual correlations and heritabilities were obtained from REML estimates of (co)variance components. Model for type traits included fixed effect of date cows were classified, effects of age in days at freshening, and stage of lactation at classification. Year-season when cows freshened was fixed effect in model for yield and SCS. Animal genetic and residual effects were random. Final score, milk, fat, and protein yields, and SCS had heritability estimates of 0.38, 0.13, 0.22, 0.09, and 0.38, respectively. Heritability estimates for type traits ranged from 0.04 to 0.52. Estimates of genetic correlations of final score with SCS and milk, fat, and protein yields were -0.64, 0.01, -0.18, and 0.06, respectively. Estimates of genetic correlations among linear type traits ranged from -0.77 to 1.00. Means of estimated breeding values for final score, stature, strength, body depth, fore udder attachment, rear udder height and width, udder cleft, udder depth, and front teat placement were significantly different between lines in the third generation. Milk, fat, and protein yields were not significantly different between lines in third generation, whereas SCS was significantly different. Estimate of genetic correlation between final score and SCS suggest that selection on PTAT would result in a change for SCS. In this study, divergent selection on PTAT of sires had a significant effect on udder and body traits, but little or no effect on feet and leg traits