The objectives of this research were to study the relationship between somatic cell count (SCC) and intramammary infection (IMI) across the dry period and the risk of subclinical mastitis at the first dairy herd improvement (DHI) test of the subsequent lactation. A secondary objective was to determine SCC test characteristics for diagnosis of IMI at both the cow and quarter levels. A total of 2...

Estimates of genetic correlations were .17 between first lactation milk yield and concurrent calving interval, .10 between second lactation milk yield and first calving interval, and .82 between first and second milk yields. Corresponding phenotypic correlations were .27, .16, and .58. Heritability estimates were .27 and .25 for first and second lactations and .15 for calving interval. Estimate...

The aim of this study was to estimate genetic parameters for female fertility and production traits in first-parity Czech Holstein cows and to quantify the effect of using this information on the accuracy of a selection index in seven different scenarios. In order to estimate genetic (co)variance components, the DMU software running an AI-REML algorithm was used. The analyses were made using a ...

Intramammary infections in breeding age and pregnant heifers are much higher than previously thought. Many of these infections can persist for long periods of time, are associated with elevated somatic cell counts, and likely impair mammary development during gestation and affect milk production after calving. Prepartum intramammary antibiotic infusion of heifer mammary glands a few weeks befor...

This review presents genetic, phenotypic, environmental and other factors influencing functional longevity in dairy cattle. High yielding cows show a lower risk of culling than low producing cows. Cows with a lower milk yield have an approximately 2.7 times greater risk of culling as compared to cows with an average milk production. Genetic estimation of the length of productive life is possibl...

The objective of present study was to derive the economic values for number of inseminations to conception, calving interval, milk yield and stillbirth, using economic data of 10 Iranian Holstein herds. The economic values were derived by using the profit function methods and differentiating a profit equation with respect to the traits of interest. The cow fertility costs herd amortization or r...

The dairy cows experience negative energy balance during early lactation and feeding Bypass fat in ration can produce higher milk yield, improved reproduction with better economics. An experiment was planned to evaluate of total mixed (TMR) supplemented @ 100 g/day animals for -21 120 days calving. Total sixteen were divided control group having eight each. effect on production, economics evalu...

Abstract Exposing Holstein dry cows to short-day (SD) photoperiod of 8 hours per day can improve milk production post-calving by 3.2 kg day, compared exposed long-day (LD) 16 during the same period. To date, no studies have evaluated effect altered period on in Jersey cows. Our objective was study LD and SD both breeds. (n=33) dried off 60 days prior their due date were either (n=9 Holstein, n=...

Increased capability for milk production has been associated with a decline in fertility of lactating cows. Nutritional requirements increase rapidly with milk production after calving and result in negative energy balance (NEBAL). NEBAL delays the time of first ovulation through inhibition of LH pulse frequency and low levels of blood glucose, insulin and insulin-like growth factor-I (IGF-I) t...