Early luteal concentrations of progesterone were a reasonable predictor of concentrations on day seven and could be used to predict animals at risk of embryo loss.
Recent trials have revealed that fertilisation failure occurred in 53.5% of dairy animals (67.5% of cows, 18.8% of heifers) – a figure that is greater than previous estimates of between 10 and 20%. And the work also revealed that energy status in early lactation significantly affected fertilisation rate.
There is a detrimental effect of a bad calving on cows’ subsequent fertility and milk production. When calving difficulty increases, fertility declines and milk yield in the first stage of lactation also decreases.
It is not genetic merit for milk production or breed that has an adverse impact on embryo quality, but rather that a variety of factors associated with milk production, such as metabolism and nutritional management, induce hostile conditions that prevent optimal embryo development.
Dairy cow fertility is negatively associated with both genetic merit and level of production, and various other factors including season of calving, lactation number and difficult calvings.
Selection of the best dairy animals for breeding could be made on the basis of juvenile predictors through the use of genotyping coupled with phenotypic profiling of type traits and metabolic parameters.
Suffolk lambs grow faster than Texel lambs when parasite infection is minimised. And the interaction between breed and level of parasite challenge shows that the breed differences in lamb growth depend on level of parasite challenge.
Grazing lambs on chicory produces heavier carcases with a better killing out percentage. Female lambs also demonstrated increased loin juiciness.
High quality maize silage is an ideal forage for finishing lambs indoors, achieving higher intake characteristics and increasing daily live weight gain by up to 50g/d compared to lambs offered medium-quality grass silage.
Dietary vitamin E level did not affect lamb performance, but those fed grass silage grew more slowly and had a higher feed conversion ratio than those fed concentrates.
