The experiment involved observations of 2,514 Holstein-Friesian cows to determine the effects of environmental factors (cow's age, calving season, weight and sex of calves, housing system) and genetic factors on gestation length in dairy cattle and the correlation between gestation length and other reproductive traits (calving ease, stillbirth rates and placental expulsion). Genetic parameters ...

This study is the first to partially quantify the potential economic benefits that a vaccine, effective at protecting cattle against malignant catarrhal fever (MCF), could accrue to pastoralists living in East Africa. The benefits would result from the removal of household resource and management costs that are traditionally incurred avoiding the disease. MCF, a fatal disease of cattle caused b...

The study was conducted to evaluate the effect of thermal stress on expression profile of genes related to apoptosis in peripartum Sahiwal cows. For this, twelve pregnant dry Sahiwal cows were selected from Livestock Research Centre at National Dairy Research Institute, Karnal. The cows were divided into two groups consisting of six Sahiwal cows each. Cows of group I calved during thermoneutral...

Data from a selection experiment for growth carried out in Brazil were analyzed in order to evaluate the direct responses on yearling weight (YW) and the correlated responses on the size and reproduction traits of cows. The experiment was started in 1976, and in 1980 three lines of Nelore cattle were established: selection (NeS), traditional (NeT), both selected for higher YW, and control (NeC)...

A total of 65 multiparous cows that calved during the hot season (n = 21), temperate season (n = 23) or cold season (n = 21) were used to investigate the relationships between heat stress, seasonal changes, metabolic traits, body condition score (BCS), resumption of ovulation and occurrence of subclinical endometritis (SE). Cows were monitored for the first 7 weeks of lactation by ultrasonograp...

the aim of this study was to estimate genetic parameters of age at first calving and its relationship with productive traits of holstein dairy cows. a total of 24491 first lactation records (2x 305d) which were collected from 1995 to 2009 were used. the general linear model (glm) procedure was applied to determine effective factors on studied traits. herd-year-season (hys) and age at first calv...

In highly seasonal environments, offspring production by vertebrates is timed to coincide with the annual peak of resource availability. For herbivores, this resource peak is represented by the annual onset and progression of the plant growth season. As plant phenology advances in response to climatic warming, there is potential for development of a mismatch between the peak of resource demands...

Angus-cross, fall-calving beef cows (n = 153) were used in this experiment. The objective was to determine whether incorporating a period of corn stover and dried distiller grains with solubles (DDGS) feeding into a preexisting nutritional program that included grazing stockpiled tall fescue affects reproductive performance and progeny growth. On Julian d 267 cows were stratified and allotted b...

A 2-yr study using primiparous and multiparous, spring-calving, crossbred beef cows was conducted to evaluate the effects of supplemental whole corn germ on reproductive performance, calf performance, and serum leptin concentrations. Each year, cows were blocked by age and BCS and assigned randomly to one of three treatments: PRE (n = 115) cows received 1.14 kg/d (DM basis) of whole corn germ f...

Standard Lactation Curves were derived for South African Holstein and Jersey cows, using 20 herd-, 18 ageand six season classes. Six herd classes were below and 13 above the average production level for both breeds. A standard lactation curve was estimated for each combination of herd-, ageand season class, which resulted in 2 160 curves per trait per breed. Variation in Holstein yields was muc...