nutrition has a significant effect on reproduction and lactation in ruminant. supply of require nutrient of dairy cows and ewes in early lactation is the main challenges that will be considered, since in most cases the animals facing negative energy balance after calving and the beginning of the period of lactation. negative energy balance may sometimes result in reduced livestock production an...

the objective of this study was to investigate the effect of principal components (pc) of the regression coefficients (co)variance matrix on the lactation curve, and on the formation of selection index to modify the curve, based on these pc’s, and as well to estimate additive genetic and phenotypic variances and heritability of the constructed selection index. lactation period of 301 d (5-305) ...

An understanding of the mechanisms regulating milk yield in sows is crucial for producers to make the best management decisions during lactation. Suckling of mammary glands by piglets is one factor that is essential for development of these glands during lactation and for the maintenance of lactation in sows. The process of mammary development is not static as the majority of it takes place in ...

Twenty one multiparous, nonpregnant, lactating dairy cows were used to assess the impact of stage of lactation on visceral tissue mass and small intestinal cell proliferation. Cows were slaughtered at each of 4 stages of lactation: 14, 90, 120, and 240 d of lactation. With stage of lactation, DMI increased through d 90 and thereafter remained similar through d 240 (quadratic). Carcass weight an...

Udder and teat morphology measurements were taken at approximately 7.5 hr after the a.m. milking for 131 East Friesian (EF) crossbred ewes at an average of 71 d in lactation. Additionally, milking time was recorded for each ewe during two evening and morning milkings. Average daily milk production, milking time, percentage of milk fat, percentage of milk protein, and somatic cell count were 2 L...

Objective To evaluate, in rat offspring, bone changes induced by excess maternal thyroxin during pregnancy and lactation, and to assess the reversibility of these changes after weaning. Material and methods Twenty Wistar rats were distributed in two groups, hyperthyroid and control, that were treated daily with L-thyroxin (50 mcg/animal) and placebo, respectively. The treatment was initiated se...

pregnancy to late lactation, whereas cytochrome oxidase remained constant. No change in the distribution of these enzymes or of protein was found at the three stages of the lactation cycle studied. 3. In mammary gland succinate-neotetrazolium reductase increased rapidly over parturition and throughout lactation; cytochrome oxidase showed a smaller increase during lactation. These increases were...

The present study was planned to find out the magnitude of environmental factors affecting udder type traits in Sahiwal cattle. Fourteen were measured for each randomly selected 100 lactating cattle maintained at Livestock Research farm, NDRI, Karnal, India. data analysed by least squares methods using general linear model procedures including parity, stage lactation and season calving classifi...