Genetic parameters for prolificacy traits for Columbia (COLU), Polypay (POLY), Rambouillet (RAMB), and Targhee (TARG) breeds of sheep were estimated with REML using animal models. Traits were number of live births (LAB), litter size at birth (LSB) and weaning (LSW), and litter weight weaned (LWW). Numbers of observations ranged from 5,140 to 7,095 for prolificacy traits and from 5,101 to 8,973 ...

Although the components of litter size (ovulation rate, embryonic survival and uterine capacity) responsive to genetic selection are well established. However, the reality in existing “hyper-prolific” sows is that increased selection pressure for numbers born has led to indirect negative effects of intra-uterine crowding, reprogramming of fetal development, less efficient post-natal growth perf...

Lactating rabbits (n=1335) were artificially inseminated to study the effect of the addition of caffeine on rabbit semen stored for up to 96 h. Concentration of 0-5 mM/l were tested. Whereas a concentration of 0.2 mM/l increased spermatozoa motility, higher concentration values adversely affected reproductive parameters. Spermatozoa stored at 18 degrees C for 72-96 h did not have the capacity t...

Mice deficient for endothelial nitric oxide synthase (NOS3(-/-)) may represent a good model for studying embryo loss and intrauterine growth retardation caused by vascular deficiencies. We determined the effects of embryo genotype (homozygous vs. heterozygous descendants with paternal or maternal source of the non-functional NOS3 allele) and maternal environment (NOS3(-/-) vs. wild-type NOS3(+/...

2. FACTORS AFFECTING MILK PRODUCTION IN GOATS 2.1 Genetic Factors 12 2.1.1 Breed Differences and Selection 2.1.2 Inbreeding 2.1.3 Crossbreeding 2.1.4 New Genetic Technology 2.2 Physiological Factors 15 2.2.1 Age 2.2.2 Seasonal Influence 2.2.3 Multiple Births 2.2.4 Length of Lactation and Dry Period 2.3 Milking Management 17 2.3.1 The Use of a Milking Machine 2.3.2 Milking Frequency and Milking ...

ne method for increasing sow prolificacy (i.e., pigs per sow per year) is to increase litters per year by reducing the interval between farrowing and subsequent conception. Although this objective may be realized by weaning the litter earlier, short lactations are often associated with reduced sow reproductive performance.1 A potential alternative to earlier weaning is to induce ovulation and c...

Economic weights have been estimated in two breeds (Latxa and Manchega) using economic and technical data collected in 41 Latxa and 12 Manchega dairy sheep flocks. The traits considered were fertility (lambing per year), prolificacy (number of lambs), milk yield (litres) and longevity (as productive life, in years). A linear function was used, relating these traits to the different costs in the...