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Antibiotic-free diets for weaned pigs allocated under unclean housing conditions generates immunological challenges that impact on growth performance leading to changes in the efficiency of nutrient utilization for lean tissue gain. Under unclean housing conditions, pigs are often exposed to different kinds of stressors that can lead to the stimulation of the immune system. This pigs immunologically challenged have higher requirements for certain AA and especially those that are involved in the immune system. Although Lys is primarily used for body protein synthesis and not in the immune system, it is the first limiting AA in most swine diets and is the reference AA in defining the ideal protein ratios for the optimal dietary supply of the other essential AA. The objective of this study was to determine the dietary Lys requirement for weaned pigs fed antibiotic-free diets and subjected to clean or unclean housing conditions. One hundred and ninety-two piglets weaned at 21±1 d and with an initial average BW of 7.2±0.50 kg BW were used in a 6-wk study. Pigs were fed corn–wheat–soybean meal based-diets to determine dietary Lys requirement. Piglets were allocated to different treatments based on BW, gender and litter of origin in a 2x4 factorial arrangement with the main factors being dietary Lys (four dietary lysine contents: 0.94, 1.09, 1.25 and 1.43%) and sanitation condition (clean and unclean).
The average daily gain (ADG) and gain to feed ratio (G:F) linearly increased (P<0.05) with dietary lysine contents, but were lower (P<0.001) under unclean sanitation conditions from day 0 to 7 but not from day 8 to 21. During days 8 to 21, the dietary standardized ileal digestible (SID) Lys linearly increased (P<0.001) the ADG and G:F. Moreover, sanitary conditions had a significant effect on ADG and G:F except during days 15 to 21 for the ADG. The ADFI was not affected by the dietary Lys level, but pigs raised under unclean conditions had a lower ADFI (P<0.01) throughout the experimental period. During the overall 21d period, the ADG was affected by the dietary Lys (linear; P<0.001) and the sanitary conditions (P<0.001), whereas only dietary lysine contents affected G:F.
The results show that the lysine requirement for piglets fed antibiotic free-diets is higher than NRC (1998) recommendation and could be similar to NRC (2012) recommendation. Unclean sanitary condition resulted in reduced growth rate and feed intake, but had no effect on feed efficiency.
Kahindi, R. K. Htoo, J. K. and Nyachoti, C. M. 2014. Effect of dietary lysine content and sanitation conditions on performance of weaned pigs fed antibiotic-free diets. Canadian Journal of Animal Science, 2014, 94(1): 115-118. DOI:10.4141/cjas2013-016