Moderate and high levels of dietary protein on clinico-biochemical and production responses of lambs to repeated Haemonchus contortus infection

Abstract

Effect of moderate and high levels of dietary protein and repeated Haemonchus contortus infection on clinical-biochemical and production responses was studied in Chokla lambs. In a 2 × 2 factorial design, two levels of protein (moderate, MP and high, HP) was supplemented to control (C) and infected (I; challenged with H. contortus) lambs. Thus, twenty-four 4 to 5 months old Chokla lambs (16.8 ± 0.53 kg) were randomly distributed into a total of 4 treatment groups of 6 animals each, designated as MPC (moderate protein control), MPI (moderate protein infected), HPC (high protein control) and HPI (high protein infected). The infected groups were drenched with 300 infective larvae (L3)/kg LW on day 0 and subsequently with 400 L3/kg LW three times a week for 10 consecutive weeks. Concentrate was restricted to 2.5% of live weight (LW) and roughage was offered ad libitum. Weekly record of body weight and faecal egg counts (FEC) and bi-weekly assessment of haematological parameters such as haemoglobin, packed cell volume, differential leucocyte count and biochemical parameters such as serum protein, albumin, iron, urea, creatinine and cholesterol were followed during the experimental period of 10 weeks. A metabolism trial was conducted after 8 weeks of experimental feeding to assess N utilization pattern in different groups. Lambs in HP had higher feed and nutrient intake (DM, CP, OM, ME) than MP. Infection exerted a more significant adverse effect on feed and nutrient intake by lambs in MP. Lambs of MPI showed a lower N balance corresponding with a lower N uptake, but had similar utilization efficiency. They also had lower (P < 0.05) average daily gain, but no significant effect on body condition score. No clinical signs were evident in infected lambs on varied protein nutrition. Although FEC and adult worm counts were higher in MPI, a varied FEC peak during 4 and 5 weeks in HP and MP, respectively was indicative of non-significant effect of increasing protein nutrition on parasite establishment. However, there was significant improvement in the ability of lambs to withstand the pathogenic effects of H. contortus infection in HPI suggesting that the diet associated with increased resilience. A decreased performance in MPI could be overcome by increasing diet palatability that ensures adequate uptake of protein.