The effect of dietary energy concentration and lysine/digestible energy ratio on growth performance and nitrogen deposition of young hybrid pigs

Abstract

An experiment was conducted to examine the effects of dietary lysine/digestible energy (DE) ratio (g/MJ) and dietary energy concentration on growth performance and body composition of young hybrid gilts from 9-1 to 25-4 kg live weight. Seven pigs were assigned to each of 10 dietary treatments consisting oflysine/DE ratios from 0-6 to 1-4 in 0-2 g/M] increments and two ). Food was provided ad libitum and at 25-4 kg all pigs were slaughtered and body composition was determined. Responses to lysine/DE ratios were different for each DE concentration. The pigs given the 16-40 MJ/kg DE diets had a higher daily liveweight gain (DLWG) and nitrogen deposition rate (NDR) than those given the 14-25 MJ/kg diets up to the 1-2 gl MJ lysine/DE ratio. Beyond this point no DE effects were evident. Lipid deposition rate (LDR) was higher for all 16-40 MJ/kg diets as compared with the 14-25 MJ/kg diets and decreased with increasing lysine/DE ratio. The 14-25 MJ/kg diets resulted in increasing efficiency of nitrogen and gross energy utilization with increasing lysinel DE ratio up to the 1-0 g/MJ ratio after which it declined. Efficiency of lipid utilization decreased with increasing lysine/DE ratio for all 14-25 MJ/kg diets. The 16-40 MJ/kg diets resulted in a decrease in nitrogen and gross energyutilization efficiency with increasing lysine/DE ratio while lipid efficiency decreased up to the 1 -0 g/MJ lysine/DE ratio after which it increased. Young hybrid pigs given high energy diets appear to be less sensitive to dietary lysine/DE ratio than those given lower energy diets. The optimum lysine/DE ratio for the genotype tested from 9 to 25 kg live weight was of the order of 1-2 g/MJ for both DE concentrations. The maximum DLWG and NDR of the genotype tested over the live-weight range of 9 to 25 kg appears to be of the order of 620 and 17 g/day (106 g/day protein deposition rate) respectively.

The effect of dietary energy concentration and total lysine/digestible energy ratio on the growth performance of weaned pigs

“…The increase in growth rate with increasing lysine:DE ratio was consistent with other reports in the literature (Gatel et al 1992;Nam and Aherne 1994;Van Lunen and Cole 1998;Smith et al 1999). In the present study, no DE × lysine:DE ratio interaction on growth rate and other performance parameters was detected.…”

“…The 4% reduction in daily feed intake that we observed on the high DE diets is in agreement with the results of previous authors (Nam and Aherne 1994;Van Lunen and Cole 1998;Smith et al 1999). It is well documented that changes in dietary energy concentration can have a great impact on feed intake (NRC 1987).…”

“…From a nutritional perspective, the increased lean growth rate of the modern pig and the increase proportion of lean in the carcass (Van Lunen and Cole 1998) suggest that nutrient requirements defined previously under different management systems may no longer suffice [National Research Council (NRC) 1998]. …”

“…It is generally accepted that growth performance in young pigs is limited by feed (energy) intake, the inevitable consequence of limited physical gut capacity (Van Lunen and Cole 1998). Expressing amino acid requirements as a ratio to energy ensures that adequate amino acids are consumed, appropriate to the animal's growth, irrespective of changing dietary energy concentration (Smith et al 1999).…”

“…In addition, the relationship between energy intake and protein deposition is assumed to be linear in pigs weighing less than 90 kg (Campbell and Taverner 1988;Rao and McCracken 1991;Bikker 1994). It is therefore essential that lysine requirements for this category of pig be expressed in relation to dietary energy concentration (Nam and Aherne 1994;Van Lunen and Cole 1998).…”