Effects of inbreeding and heterosis and the difference between them were estimated by comparing linecross (L), topcross (T), inbred (I) and control line (C) Hereford females for reproductive and preweaning growth traits of their progeny. Inbred females (average inbreeding coefficient = 26.5%) originated from four single-sire inbred lines. Control females (average inbreeding coefficient = 6.9%) ...

this experiment was conducted using 172 male lambs of ghezel and mehraban breeds for two periods of 60 and 80 days. two systems of fattening were studied. the first group of lambs entered feedlot boxes immediately after weaning (spring) but the second group being fed on pasture, entered the experiment approximately 4 months later (autumn). fattening periods were 60 and 80 days. the average wean...

Sheep production is affected by genetic and non-genetic factors. A knowledge of these factors is essential for efficient management and for the accurate estimation of breeding values. The objective of this study was to establish the non-genetic factors which affect birth weight and weaning weight in Dorper, Mutton Merino and indigenous Sabi sheep breeds. A total of 2,625 birth and weaning weigh...

Gilt progeny have lighter weaning weights and greater postweaning medication and mortality rates compared with the progeny of older parity sows. Because weaning weight has been positively correlated with postweaning survival, this study aimed to determine whether the provision of supplemental milk preweaning could improve weaning weight and subsequent weights as well as postweaning survival of ...

BACKGROUND The recommended age of introduction of solids food to the diet of infants (weaning) has recently been increased in the UK to 6 months, but most babies are still weaned before the age of 4 months. AIMS To examine what predicts the age of weaning and how this relates to weight gain and morbidity using data from a population based cohort. METHODS Parents of 923 term infants born in ...

The effects of dam previous reproductive status (PRS) on the pre-adjustment of weaning weight for genetic evaluation (WWT) was examined for Santa Gertrudis (SANTA), Brahman (BRAH) and Tropical Composite (TCOMP) breeds of beef cattle. Weaning weight records were classified into 3 groups according to the dam’s PRS: whether in the last year, she had reared a bull calf (PBC), a heifer calf (PHC) or...

Economical and biological efficiencies of beef production to weaning and to slaughter were estimated in three groups, different in milk available (low, medium, and high) to the calves but with the same potential for growth. Data from different breed groups of cows (low [L] = Hereford x Angus, medium [M] = Red Poll x Angus, and high [H] = Milking Shorthorn x Angus) were used. Economical efficien...

The present study was performed to study the effect of inbreeding on the pre-weaning growth traits including the birth weight (BW), weaning weight (WW), average daily gain (ADG), Kleiber ratio (KR) and lamb survival from birth to weaning (SUR) in Baluchi, Iran-Black and Zandi sheep. Significant positive inbreeding trends were found only for Baluchi and Iran-Black breeds as 0.038 and 0.278, resp...

Data from 69,525 animals were used to compare two types of analyses, one of them having the weaning management group (WEMANG) included as an effect in the contemporary group (F_WEMANG) and the other considering the weaning management group as a random effect, not related to the mathematical model (R_WEMANG) for post-weaning traits. The components of (co)variance were estimated for pre-weaning t...