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 ...

Three levels of dietary crude protein (CP), provided by soybean meal, were fed to determine effects of protein intake on progesterone and luteinizing hormone (LH) concentrations in serum of early postpartum high-producing dairy cows. Serum LH increased between the first and second weeks of lactation in all groups. Cows fed 12.7% CP had decreased basal serum LH levels (1.1 + .04 ng/ml) as compar...

The aim of the present study was to show the distribution of cows by days in milk (DIM) at first AI, effect of DIM at first AI on reproductive performance and some factors influencing DIM at first AI. A total of 767 Holstein Frisian cows that calved from January 2004 to December 2007 in 14 dairy herds were used. The first AI conception rate (FAICR) was 34.0%. Seventy-five percent of the cows we...

Thirty-six lactating Alpine does were used to determine effects of stage of lactation and level of feed intake on energy utilization. Twelve does were assigned to measurement periods in early, mid, and late lactation (wk 5, 13, and 27, respectively). For 6 does of each group, after ad libitum consumption of a 60% concentrate diet, feed intake was restricted to near the metabolizable energy (ME)...

The aim of the present study was to compare the occurrence and duration of clinical mastitis in different seasons, stages of lactation period and parities in a Holstein dairy farm in Iran. A retrospective epidemiological survey from April 2005 to March 2008 was conducted on 884 clinical mastitis cases of 7437 lactations. Data of each case including calendar-date of mastitis onset, days in milk ...

A. PR expression and regulation IV. Progesterone Regulation of Gene Expression in the Uterus, Ovary, and Chick Oviduct A. Progesterone effects on proliferation and decidu-alization in the uterus during the menstrual cycle B. Progesterone regulation of insulin-like growth factor (IGF) pathways in the endometrium C. Control of ovulation D. Implantation, uterine proliferation, and early pregnancy ...

d before initiating treatments. Cows were blocked by lactation number and assigned randomly to 3 treatments consisting of variations of the Ovsynch protocol. Cows in Cosynch-48 and Ovsynch received injections of GnRH 7 d before and 48 h after a PGF injection. Fixed-time inseminations (TAI) were made at the time of the second GnRH injection (0 h; Cosynch-48) or 24 h (Ovsynch). Those in Cosynch-7...