The effect of energy intake, genotype, and body weight on protein retention in pigs when dietary lysine is the first-limiting factor.

Abstract

This study tested the hypothesis that the effect of lysine intake, if first-limiting, on protein retention in growing pigs is completely independent of the effects of energy intake, differences in the protein retention capacity among genotypes and gender, and body weight. Protein retention, using the nitrogen balance technique, was measured in 12 castrated male German Landrace and Pietrain pigs at 44 and 77 kg of BW and at two energy intake levels (1.1 and 1.3 MJ ME/kg BW.75). All animals received a constant amount of a basal diet that provided a protein intake of 220 g/d and a total lysine intake of 13 g/d. Appropriate amounts of cornstarch were offered additionally to reach the intended energy intake levels. The results show that neither energy intake nor breed had any effect on the level of protein retention, whereas, at 77 kg BW, protein retention was significantly lower than at 44 kg (117.8 and 123.5 g/d, respectively), which can be attributed to the higher requirement for maintenance. The results of this experiment and the linearity of the relationship between protein retention and lysine intake as shown by several authors simplify both the prediction of protein retention from lysine intake and the calculation of the lysine requirement for a particular protein retention. However, to ensure accuracy of these predictions, it is essential to know when ratios of lysine to other amino acids and to energy and capacity for protein retention in the animal become first-limiting.

Protein to energy ratios in goldfish (Carassius auratus) diets

“…There is strong evidence in several reports that the requirement for maximizing protein gain is higher than that required to maximize weight gain (RODEHUTSCORD et al, 1997;SUSENBETH et al, 1999;HAULER;CARTER, 2001;BUREAU;ENCARNAÇÃO, 2006). Similarly, we observed in our study that Goldfish required a higher amount or DP (between 41.0 and 42.0) to sustain maximum feed utilization which supports previous studies with other farmed fish species.…”

Lysine requirement for maintenance in growing pigs

“…Provided that the marginal efficiency of lysine utilization is not affected by BW (Susenbeth, 1995;Dourmad et al, 1996;Möhn et al, 2000), the negative effect of BW or body components on RP indicates the increasing demand of lysine for maintenance with body size. However, as a consequence of overestimating protein retention through the N-balance method, a correction for it of 11% (Susenbeth et al, 1999) should be applied. For the further calculations, lysine concentration in retained body protein was assumed to be 7.2% (Susenbeth, 1995;GfE, 2006) and dietary lysine to be utilized for retention with an efficiency of 0.63 (Bikker, 1994;Susenbeth et al, 1999;GfE, 2006).…”

“…However, as a consequence of overestimating protein retention through the N-balance method, a correction for it of 11% (Susenbeth et al, 1999) should be applied. For the further calculations, lysine concentration in retained body protein was assumed to be 7.2% (Susenbeth, 1995;GfE, 2006) and dietary lysine to be utilized for retention with an efficiency of 0.63 (Bikker, 1994;Susenbeth et al, 1999;GfE, 2006). Therefore, the respective regression coefficients and their SE of Eqs.…”

Digestibilidade aparente da dieta e balanço do nitrogênio em suínos de diferentes grupos genéticos com ou sem restrição alimentar

“…Em dietas para suínos de duas linhagens híbridas comerciais selecionadas para PDmax elevados, a retenção de N diferiu em 8% na fase de crescimento e em 4% na terminação, contudo essa diferença não se traduziu em ganho muscular (GOMES et al, 2000). A diferença na retenção de N entre os grupos genéticos foi demonstrada em vários trabalhos, sendo associada à composição genética dos suínos (SUSENBETH et al, 1999, GOMES et al, 2000. A eficiência nutricional de grupos genéticos distintos pode estar relacionada ao programa nutricional ou alimentar.…”