Effects of nutrition pre-partum and post partum on subsequent productivityand health of N'Dama cows infected with Trypanosoma congolense

This experiment studied the effects of body condition, long- and short-term levels of nutrition and trypanosomosis infection on the productivity of N' Dama cows using a 2 x 2 x 2 factorial cross-over design. Pre-partum, 23 cow s received supplements for 6 months (H), the other group of 20 for 2 months (L). Bath groups grazed native pastures. Two days post partum, half the co ws from each group were placed on a basal (B) or supplemented (S) plane of nutrition. The diet of concentrate, groundnut hay and andropogon hay was th e same, only the quantities differed. Four weeks post partum half the anima ls in each group were inoculated with T. congolense organisms (I), the othe rs acted as controls (C). The trial continued for a further 6 weeks. Pre-partum nutrition (H, L had no effect on dry-matter intake (DMI) but pre -partum feeding (H) improved post-partum productivity, evident by higher da rn live weights (P < 0.05), body condition (P < 0.001), calf birth weight ( P < 0.05) and calf live-weight gain (P < 0.01). Post-partum nutrition had n o effect on productivity. Trypanosomosis infection caused a reduction (P < 0.05) in total DMI. The decline in groundnut hay and concentrate intake was proportionally (P < 0.001) greater in the S-I group than in the B-I group. A low plane of nutrition pre-partum depressed milk yield but increased fat concentration (P < 0.05). Infection significantly reduced milk offtake (P < 0.05). The reduction in milk offtake (P < 0.01) and calf live weight (P < 0.05) were proportionally larger in the B-I than in the S-I group. Infecti on caused a decline in milk protein concentration (P < 0.05) and protein yi eld (P < 0.01) which teas independent of dietary effects. Infection reduced (P < 0.01) the packed-cell volume but there were no interactions with diet . None of the cows was pregnant 150 days post partum but seven were cycling , 3(5) in the H-S-I group, 2(7) in the H-B-I group, 1(5) in the L-B-I group and 1(5) in the LS-C group. These results suggest that S-I cows attempted to maintain milk yield at the expense of live weight whereas the B-I cows h ad insufficient live-weight reserves that could be mobilized. This suggests the nutritional balance and changes in weight at the time of infection mig ht be more important than historical planes of nutrition.