Early lactation parameters are difficult to estimate from commercial dairy records due to the small number of records available before the peak of production. A biological model of lactation was used with weekly milk records from a single Holstein herd to estimate these early lactation parameters and the secretion rate of milk from the average cell throughout lactation. A genetic analysis of th...

test day records of first lactation holstein cows from 1996 to 2008 were obtained from animal breeding center of iran and used in this research. data consisted of 872125 test-day milk records of 95816 cows from 59 herds. (co)variance components and genetic parameters were estimated using random regression model via gibbs sampling method. two order legendre polynomials and third coefficient of w...

random regression models (rrm) are used for genetic estimations of milk traits in dairy cows. rrm utilize data on traits that are repeated during the time, such as milk trait, which allows of the evaluation of the test day production information. in this study, to estimate genetic parameters for milk production trait, test day records (tdr) were collected from the first lactation of holstein co...

The contribution of hypothalamic appetite-regulating peptides to further hyperphagia accompanying the course of lactation in rats was investigated by using PCR array and real-time PCR. Furthermore, changes in the mRNA expression for appetite-regulating peptides in the hypothalamic arcuate nucleus (ARC) were analyzed at all stages of pregnancy and lactation, and also after weaning. Food intake w...

Lactation alters maternal metabolism and increases food intake in rats to support milk production. Pancreatic lipase (PL) is primarily responsible for fat digestion in adults and is regulated by dietary fat. The present research determined the regulation of PL by lactation and dietary fat. In Expt 1, eighteen Sprague-Dawley dams and twelve age-matched virgins (controls) were fed a low-fat diet ...

Most studies on the factors limiting sustained energy intake (SusEI) during peak lactation period have been performed in females at the 1st lactation event. However, an inconsistent change in SusEI is observed between the 1st and 2nd lactation event. Thus, the limits to SusEI may be associated with reproductive experiences, but the effects of reproductive experiences on SusEI or reproductive ou...

The objective of this study was to estimates the genetic and environmental components for the lactation curve parameters, milk yield, age at first calving (AFC), calving interval (CI) and somatic cell count (SCC) in Iranian Holstein cows. The dataset consisted of 210625 test day records from 25883 cows with milk yield in the first parity recorded from July 2002 to September 2007 in a total of 9...

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...

Weekly total body energy content (TBEC) was calculated for 444 Holstein cows in their first 3 lactations. These calculations were based on body lipid and protein changes predicted from weekly changes in body condition score and live weight of each cow. In first lactation, cows lost TBEC during the initial 8 wk, regained it by wk 22, and continued to build up their reserves until wk 37. Cows sta...