The objective of this study was to compare the environmental impact of Jersey or Holstein milk production sufficient to yield 500,000 t of cheese (equivalent cheese yield) both with and without recombinant bovine somatotropin use. The deterministic model used 2009 DairyMetrics (Dairy Records Management Systems, Raleigh, NC) population data for milk yield and composition (Jersey: 20.9 kg/d, 4.8%...

The objective of this study was to quantify how the pattern of milk production relative to time from calving is affected by parity in cows fed high quality rations. For this purpose two models; those of Emmans and Fisher (1986) and Dijkstra et al. (1997), were considered. Comparison with Wood’s (1967) function was made to evaluate their fitting ability. Daily records of milk yield from 40 cows ...

Records from the El-Serw research station belonging to Animal Production Research Institute were used to estimate the genetic parameters for the economically most important milk and growth traits in the Zaraibi goat breed. There were 99 and 110 half-sib families over the periods 1995-2003 and 1990-2003 for milk and growth traits, respectively. Milk traits were, milk yield during the first 90 da...

Since the initial report in 1978 of galactopoietic effects of a photoperiod of 16 h of light:8 h of darkness, numerous studies have confirmed long-day stimulation of milk yield. The endocrine factor(s) responsible for increased milk yield, however, has eluded identification. Recent studies suggest that insulin-like growth factor-I (IGF-I) may mediate the galactopoietic response to long day phot...

Milk yield and quality were observed on 93 Angus, Brahman, and reciprocal-cross cows over 3 yr to evaluate the interactions of direct and maternal breed effects and heterosis with forage environment. Forage environments were common bermudagrass (BG), endophyte-infected tall fescue (E+), and a rotational system (ROT) of both forages, in which each forage (BG or E+) was grazed during its appropri...

The objectives of this study were to estimate genetic correlations among body condition score (BCS), dairy form, milk yield, and days open in US Holsteins and investigate the potential of using BCS or dairy form evaluations as early indicators of days open. Dairy form and BCS obtained from the Holstein Association USA, Inc., were merged with mature equivalents (ME) for milk yields and days open...

Results from 4 switchback field trials involving 608 cows were combined to assess the effects of a protected B vitamin blend (BVB) vs 10 mg of unprotected biotin upon milk yield (kg), fat %, protein %, fat yield (kg) and protein yield (kg) in primiparous and multiparous cows. Trials consisted of 3 DHIA periods executed in the order control-test-control. Cows from 45 to 300 days in milk (DIM) at...

The aim of this present study is to describe changes occurring during the milking of cows in various periods following the introduction of an AMS (automatic milking system). The following cow milking parameters were analysed: milkings per cow per day, milking yield, milking speed and milking duration. An increase in milk yield in AMS barns has been found to be possible, but it is affected by a ...

The objective of the present study was to evaluate effects postpartum oral calcium supplementation on milk yield, energy-corrected fat concentration, protein and somatic cell count linear score across first 3 monthly tests postpartum, peak risk pregnancy at service, hazard by 150 d in 1,129 multiparous Jersey × Holstein crossbreed cows from 2 commercial dairies. After calving, were systematical...

The study was conducted to find the association of -Lactoglobulin locus with the milk performance traits in 157 lactating Sahiwal cows maintained at Cattle yard, NDRI, Karnal. Two different variants of -Lactoglobulin were detected from DNA by PCR-RFLP. It was found that the frequency of B allele was predominantly high (0.84± 0.03) than that of A allele (0.16± 0.03) in the population studied. ...