Genetic parameters of milk, fat, and protein yields were estimated in the first 3 lactations for registered Tunisian Holsteins. Data included 140,187; 97,404; and 62,221 test-day production records collected on 22,538; 15,257; and 9,722 first-, second-, and third-parity cows, respectively. Records were of cows calving from 1992 to 2004 in 96 herds. (Co)variance components were estimated by Baye...

1 Interpretative Summary: Effect of oral calcium supplementation on early lactation health 1 and milk yield in commercial dairy herds. By Oetzel and Miller, page 000. Low blood 2 calcium often occurs in older cows around calving and impairs subsequent health and milk yield. 3 Second lactation or greater cows in 2 commercial dairies with effective milk fever prevention 4 were divided into contro...

The effects of kappa-casein (kappa-CN) and beta-lactoglobulin (beta-LG) loci on milk production traits (milk, fat, protein, and lactose yield, fat, protein, and lactose content) and reproductive performance (gestation length, calving interval, age at first and second calving, number of services per conception) was estimated for 278 Holstein cows in the first 2 lactations. Genotypes of kappa-CN ...

four hundred and ninety five smallholder dairy farms in 52 villages of different cities in chaharmohal and bakhtiari province including 1321 lactating cows and totalling 2811 total mature cows (lactating and dry)were employed during winter 2009 to summer 2010 to estimate the economic opportunities as per cow in smallholder dairy farms. a questionnaire survey was employed to collect data from th...

The effect of growth rate from birth through 30 months of age on the reproductive performance of Polled Hereford heifers calving as 2-year-olds was examined. Heifers with high gains during the first winter as weanlings had higher breeding efficiency when bred as yearlings, had larger pelvic areas as 2-year-olds, gave birth to larger calves, had less calving difficulty at first parturition and h...

introduction secondary sex ratio (ssr) is the proportion of males to females at birth. it has been shown in many different mammalian species, many factors are associated with ssr. changes in secondary sex ratio in dairy cows is considered economically important and the ability to change it could affect the revenues and profitability of a dairy farm. thus, sperm or embryo sexing techniques in re...

Twinning costs the dairy industry an estimated $96 million each year. Twin pregnancy occurrence in high-producing cows is primarily a result of multiple ovulations associated with low circulating concentrations progesterone due to high milk production. The present retrospective observational study aimed identify associations between (1) previous parity yield and subsequent twin birth prevalence...

OBJECTIVE Aim of the current comparative study was to evaluate production outputs, reproduction efficiency and functional traits in dual-purpose Fleckvieh and Braunvieh cows, reared under temperate European conditions. METHODS A data-set from 414 Fleckvieh and 42 Braunvieh cows and 799 lactations was analysed. ID tag number, milk yield per milking session, number of steps/interval and milk co...

The aim of this study was to determine the effect of prepartum somatotropin injection in late-pregnant Holstein heifers on metabolism, milk production and resumption of postpartum ovulation. For this study, 31 late-pregnant Holstein heifers were used. The heifers were assigned randomly into two treatments: (1) 500 mg sc injections of somatotropin (somatotropin treatment, n = 15) at -35 and -21 ...

I t is a common observation of dairymen that the milk flow of the dairy cow rises for some time after calving and then declines steadily. In preceding papers 1 we have presented data and have offered an interpretation for the declining segment of the curve of milk secretion. Having found that after the first month of lactation the curve of milk secretion with the advance of the period of lactat...