Abstract:
Twenty, 7-8 month- old worm free male West African Dwarf (WAD) goats, were used to study the effect of protein supplementation on susceptibility to mixed infections of Haemonchus contortus and Trichostrongylus colubriformis. The objective of the study was to provide information on the effect of infection of WAD goats with the most prevalent native strain of gastrointestinal (GI) nematodes (Haemonchus contortus and Trichostrongylus colubriformis) and its interaction with dietary protein. The goats were assigned to four groups each containing five animals. Two groups were offered forages with concentrate supplement containing 17.06% crude protein, whereas the other two groups were offered forages alone. After an initial period of 4 weeks on the feeding regimen, two groups were selected for infection, one each from the supplemented and unsupplemented groups. An escalating infection of 500 infective larvae (L3), 1000L3, 2000L3 and 4000L3 was given consecutively for four weeks. The other two groups were used as non infected controls. Body weight, body condition scores (BCS) and packed cell volume (PCV), as well as serum biochemistry were determined for individual goats on the first day of infection (D0). These parameters were subsequently determined weekly throughout the duration of the experiment, which lasted for forty two days. Feed and water intakes were determined daily and the average weekly intakes were calculated. Patency and level of infection were monitored by carrying out faecal egg counts (FEC) twice weekly. At the end of the forty two day period (D42), all the animals were humanely sacrificed to recover both abomasal and intestinal worms. The carcasses were weighed and the dressing percentages calculated for each goat. The results showed that there was a positive correlation between protein supplementation and body weight gain and body condition score. However, protein supplementation had no significant (P> 0.05) effect on the PCV, total serum protein levels and serum albumin. Supplemented goats shed significantly fewer helminth eggs in faeces and harboured smaller burdens of the two worm species compared to unsupplemented goats. There was a negative but significant correlation between worm burden and body weight and BCS. The correlation between worm burden and PCV was also negative but not significant (P > 0.05), while that between worm burden and FEC was positive and significant (P < 0.05). Infection significantly (P < 0.05) affected feed intake but did not affect water intake. Dressing percentage was significantly affected by supplementation. These results therefore demonstrate that nutritional supplementation enhances the resistance of WAD goats to mixed infections of H. contortus and T. colubriformis and results in their improved performance.
