Effect of energy intake on protein and energy metabolism of boars of high genetic potential for lean growth

Abstract

Two experiments were conducted each using one batch of six Landrace littermate, entire male, pedigree pigs in a Latin-square change-over study of the effects of energy intake on nitrogen and energy metabolism over the range 33 to 88 kg live weight. One animal from each litter was slaughtered at 33 kg body weight to obtain initial body composition data. Five feeding levels (80, 100, 120, 140 and 160g/kg M0·63) were used during five consecutive metabolism trials each of 11-days duration, excreta being collected during the last 7 days. The pigs were housed in individual metabolism cages and the diets were offered in liquid form (approx. 300 g dry matter (DM) per kg) twice daily at 09.00 and 16.00 h. Heat production was measured for 1 day during each balance period in an open-circuit respiration chamber. The average daily gain, nitrogen retention, heat production and energy retention increased linearly (P < 0·001) with increasing metabolizable energy (ME) intake. The relationship between energy intake and protein deposition was linear up to levels above the normal ad libitum consumption of energy. Protein deposition potential of these high genetic potential pigs was at least 200 g/day, and tended to be constant between 35 and 85 kg live weight. From the combined results of experiments 1 and 2, the energy requirement for maintenance was 0·982 MJ ME per kg M0·63 per day and the decrease in protein deposition was approximately 6 g/MJ reduction in ME within the range of practical energy intakes.

Effects of the dietary protein content and the feeding level on protein and energy metabolism in Iberian pigs growing from 50 to 100 kg body weight

“…The low marginal efficiency of PD at restricted intakes (1.34 g PD per MJ increase in ME intake) is associated with the low PD max found in the Iberian pig at this stage of growth. This observation confirms the suggestion that the decrease in PD due to restriction in energy allowance would be greater in pigs of higher genetic potential for lean tissue deposition (Campbell and Taverner, 1988;Rao and McCracken, 1991;Quiniou et al, 1996). In Iberian pigs growing from 15 to 50 kg BW, Nieto et al (2002) reported a marginal efficiency for PD of 2.81 g PD per MJ ME with the diet that provided the optimal protein concentration for growth.…”

“…Noblet et al (1999) and Van Milgen and Noblet (1999) concluded that body muscle and, even more importantly, visceral mass explain a large part in the variation of ME m . Higher maintenance energy requirements in lean genotypes are supported by the findings of Thorbek et al (1984), Campbell and Taverner (1988) and Rao and McCracken (1991).…”

The effect of dietary protein content and feeding level on the rate of protein deposition and energy utilization in growing Iberian pigs from 15 to 50 kg body weight

“…Part of this information derives from studies made with modern strains of pigs of high genetic potential. For these animals, energy intake seems to be a limiting dietary factor and, in the young animal, the major constraint on growth (Close et al 1979;Campbell & Dunkin, 1983a,b;Rao & McCracken, 1991. The results suggest that the selection has raised the genetic capacity of these pigs for lean gain beyond the upper limit of appetite.…”

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

“…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).…”