Inbred strains generated from native and exotic pigs were compared with their F1and f2 backcross populations for a range of litter size performance traits. Animals were intensively reared and at 81⁄2 months of age, the inbred genotypes from each strain were reciprocally mated to each other to generate F1 crossbred genotypes; while gilts from each crossbred group were backcrossed to their male p...

The objective of this study was to evaluate genetic and phenotypic parameters for some reproductive traits of Black Bengal does. Genetic parameters were estimated by Residual Maximum Likelihood procedure, fitting an animal model ignoring maternal genetic or permanent environmental effects. The least-squares means of litter size at birth (LSB), litter size at weaning (LSW), litter weight at birt...

the raini cashmere goat is one of the iranian goat breeds with a high economic value on international markets due to its high production and high quality. the bmp15 gene regulates granulose cell proliferation and differentiation by promoting granulosa cell mitosis, suppressing follicle-stimulating hormone receptor expression, and stimulating the kit ligand expression. this gene plays a pivotal ...

Despite the long history of purebred dogs and the large number of existing breeds, few studies of canine litter size based upon a large number of breeds exist. Previous studies are either old or include only one or a few selected breeds. The aim of this large-scale retrospective study was to estimate the mean litter size in a large population of purebred dogs and to describe some factors that m...

EVERAL investigators have reported the results of selecting for measures of growth rate or body size in mice (GOODALE 1938; MACARTHUR 1944, 1949; FALCONER 1953; RAHNEFELD et al. 1963; ROBERTS 1967). Direct response to selection has been substantial in each of these cases. Litter size has been shown to increase in several of the lines, the increase in the experiment reported by RAHNEFELD et al. ...

Data on litter production traits of does, involving 1120 litters, was collected over a 10-year period (1984 to 1994) and analyzed to estimate heritability and repeatability. Locally adapted does and bucks of predominantly New Zealand White breeding were involved. Traits studied were total litter size born and born alive, and litter size and weight at 21 days, 28 days (weaning) and 84 days (mark...

Variance components were estimated for maturing age, first litter size, and animal size in Finnish minks. The fitted animal models had direct genetic and maternal genetic effects, litter effects, and maternal environmental effects. Multivariate analysis was performed to determine covariances between the traits. Maternal effects represented a significant source of phenotypic variance in the matu...

Economic values or weights measure the net economic gain per unit genetic increase of a given trait. These were derived for sow productivity traits for use as weighting factors in a dam line selection index used by purebred or nucleus dam line breeders. The profit function approach was used in order to provide flexibility to alternative production systems, market requirements or population trai...

Laboratory mice (strain MF1) were used to determine whether sustainable rates of energy intake are limited during lactation. Mice raising natural-sized litters (N=71) reached an asymptote in their daily food intake between days 13 and 16 of lactation at 23.1 g x day(-1) and also between litter sizes of 9 and 15 pups (22.8 g x day(-1)). A second group of 37 females had their litter sizes manipul...