A noninvasive method for measuring mammary apoptosis and epithelial cell activation in dairy animals using microparticles extracted from milk

AbstractMilk production from dairy animals has been described in terms of 3 processes: the increase in secretory cell numbers in late pregnancy and early lactation, secretion rate of milk per cell, and the decline in cell numbers as lactation progresses. This latter process is thought to be determined by the level of programmed cell death (apoptosis) found in the animal. Until now, apoptosis has been measured by taking udder biopsies, using magnetic resonance imaging scans, or using animals postmortem. This paper describes an alternative, noninvasive method for estimating apoptosis by measuring microparticles in milk samples. Microparticles are the product of several processes in dairy animals, including apoptosis. Milk samples from 12 Holstein cows, at or past peak lactation, were collected at 5 monthly samplings. The samples (n=57) were used to measure the number of microparticles and calculate microparticle density for 4 metrics: annexin V positive and merocyanine 540 dye positive, for both and total particles, in both whole milk (WM) and spun milk. Various measures of milk production were also recorded for the 12 cows, including daily milk yield, fat and protein percentage in the milk, somatic cell count, and the days in milk when the samples were taken. A high correlation was found between the 4 WM microparticle densities and days in milk (0.46 to 0.64), and a moderate correlation between WM microparticle densities and daily milk yield (−0.33 to −0.44). No significant relationships were found involving spun milk samples, somatic cell count, or fat and protein percentage. General linear model analyses revealed differences between cows for both level of microparticle density and its rate of change in late lactation. Persistency of lactation was also found to be correlated with the WM microparticle traits (−0.65 to −0.32). As apoptosis is likely to be the major contributor to microparticle numbers in late lactation, this work found a noninvasive method for estimating apoptosis that gave promising results. Further investigation is required to find out the factors affecting microparticle production and how it changes throughout lactation

The development of lamb production systems using one type of Sudanese sheep

The study compares the growth performance of Watish lambs in the Sudan under traditional production systems with those of lambs kept in feedlots and on irrigated pastures by a series of trials designed to investigate the components of more intensive systems of lamb production. It investigates some attributes of lamb carcasses in light of local market conditions and studies why lambs kept under the traditional system are sold at over two years of age while more intensively reared lambs can be sold at 8 to 14 months of age depending on the system

Selection as a means of improving a self-contained sheep breed, eg. Clun Forest

SIGLEAvailable from British Library Document Supply Centre- DSC:D75829/87 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

The growth and carcass weight of young Watish Sudan Desert sheep when fed concentrate supplements to berseem (Medicago sativa) grazing

Young Watish lambs grazing berseem grow at 148 and 105 g/day for males & females respectively, over a 20-week period. The provision of various concentrate supplements marginally increased live-weight gains but this practice was not recommended as being of economic value. Hot carcass weight of young Watish lambs was highly related to live-weight at slaughter but killing-out percentage was less so. The practical implications of these results are discussed

Milk production and growth performance of a Turkish Awassi flock when outcrossed with Israeli improved Awassi rams

The Awassi population (22,000 ewes) of the Ceylanpinar State Farm, situated in south-east Anatolia, is used to produce both meat and milk under a semi-intensive system of management. Rams of the intensively managed Israeli Improved Awassi type were introduced to the Ceylanpinar flock and both growth and milk production were monitored between 1993 and 1999. Individual performance of lambs and yearling ewes were recorded and analysed by genotype (Ceylanpinar (C), Israeli Improved Awassi (I)xCeylanpinar (F1), CxF1 (B1C), IxF1 (B1I), B1CxC (B2C.C). Using least-squares analysis to account for the effect of flock, year, sex, birth type and weaning age, the least-squares mean weaning weights for male lambs of the different genotypes were 18.3 (C), 19.3 (F1), 19.7 (B1I), 18.3 (B1C) and 18.2 (B2C.C) kg. Similar trends were found for other growth traits. Least squares analysis of milk production between days 90 and 150 of lactation and the 120 days post weaning also demonstrated a superiority of F1 and B1I over C ewes. The offspring of the highly selected Israeli Improved Awassi genotypes, from an intensive production system, were found to give higher performance than local sheep, in a semi-intensive system. Increases of between 5 (growth) and 20% (milk) were found when comparing the F1 to the Ceylanpinar sheep. © 2001 Elsevier Science B.V. All rights reserved

Genetic parameters derived from using a biological model of lactation on records of commercial dairy cows

The object of this study was to investigate the genetics of lactation curve parameters derived from a biological model of lactation and the relationships among them. This biological model fitted 2 logistic curves to mimic the initial increase in milk secretory cell numbers in early lactation and the progression of apoptosis in late lactation. Records from 82,255 Holstein-Friesian heifers from commercial dairy herds in the United Kingdom, recorded from 1994 to 2003, were analyzed. The heritabilities of 2 lactation curve parameters, maximum secretion potential and relative cell death rate, were 0.27 and 0.08 respectively. Maximum secretion potential was highly genetically correlated with peak yield (0.99), and relative cell death rate was highly correlated with persistency of lactation (0.84). Heritability values for the traits analyzed showed a characteristic pattern. Total milk yield traits, maximum secretion potential, and peak yield had similar and moderate heritabilities (similar to 0.3). Traits associated with late lactation had lower heritability values (similar to 0.1), whereas day of peak yield and early lactation traits had little genetic variation. The permanent environmental variance of the various traits ranged from 0.08 to 0.26 of the phenotypic variance. Parameters from the 2 logistic curves were not highly correlated, suggesting that selection programs could be devised to exploit genetic variation in both aspects of lactation independently