Nutritional effects of supplementary feeding on maternal blood metabolites, cortisol, thyroid hormones levels and on outcome of pregnancy of dry season kidding Tswana goats

Abstract

The nutritional effects on maternal blood metabolites levels and outcome of pregnancy in goats were investigated. The supplementary diet (106g/kg crude protein) was given to S animals at a rate of 400g/animal/d. Two weeks prior to and at parturition, S (Supplemented) does were heavier (P<0.05) and were in better (P<0.001) body condition than C (Control) animals. Eighty-nine percent of S animals kidded including abortions, while the value was 79 for C animals, however the difference was not significant (P>0.05). Prolificacy was higher for S but was not significantly different (P>0.05; 1.93±0.17 versus 1.64±0.18kid/doe for S and C respectively). Percentage reproductive wastage was lower (P<0.05) in S than C group. Birth weights were similar between S and C animals (P>0.05; 2.70±0.11 and 2.60±0.13kg). A significant (P<0.05) difference was recorded on the concentrations of cholesterol, haematocrit, triiodothyronine (T3) and tetraiodothyronine (T4) (P<0.01) between the groups, S animals having high values than C animals.It is discussed that infectious agents were not a prime cause of reproductive wastage. Kid viability at birth contributed to reproductive wastage and difference in T3 and T4 may be involved but not cortisol. Supplementary feeding of pregnant goats grazing natural pasture during the dry season can offset the detrimental effects of maternal nutritional stress and therefore reducing reproductive wastage.