Physiological responses to divergent selection for daily food intake or lean growth rate in pigs

Abstract

Correlated responses in physiological traits to divergent selection on components of efficient lean growth identified physiological traits for use as predictors of genetic merit and provided a biological explanation for the between-selection line differences in protein and lipid deposition. Responses (differences between high (H) and low (L) selection lines) in protein metabolism during ad-libitum feeding were associated with divergent selection for daily food intake (DFI) (reduced serum creatinine concentration (H = 1·30 v. L = 1·56, s.e.d. 0·08 mg/dl)) and for lean growth rate on an ad-libitum feeding regime (LGA) (increased serum urea (H = 48 v. L = 36, s.e.d. 4 mg/dl) and creatinine (H = 1·74 v. L = 1·45 mg/dl)) concentrations, but not with selection for lean growth on a restricted feeding regime (LGS). Following 24-h fasting, responses in lipid metabolism, in the form of higher serum non-esterified fatty acid concentrations, were detected with divergent selection for both LGA (399 v. 248, s.e.d. 66 µmol/l) and LGS (H = 361 v. L = 107 µmol/l). The high LGS line appeared to ‘preserve’ protein to a greater extent than the high LGA line and similarly there was greater maintenance of lipid depots by the low LGS line compared with the low LGA line. A tentative ranking of the two pairs of lean growth selection lines on the basis of ‘importance’ of protein deposition would be high LGS, high LGA, low LGA and low LGS.Coheritabilities for serum creatinine concentration with predicted lysine balance and lysine required for protein deposition (-0·17 and 0·17, s.e. 0·08) indicated that serum creatinine concentration may usefully be included in breeding value prediction for lysine requirement and protein deposition to increase the accuracy of predicted genetic merit.Fasting did not increase the coheritabilities for serum creatinine concentration, so inclusion of serum creatinine concentration in a selection criterion for dietary lysine requirement or protein deposition does not require withdrawal of food before blood sampling animals.

Reduction of the crude protein content of diets supplemented with essential amino acids for piglets weighing 15 to 30 kilograms

“…The concentration of creatinine in the blood plasma or serum is highly correlated with the amount of lean meat in the pig carcass, and nitrogen intake appears to have little effect on the serum creatinine concentration (Cameron et al, 2003), corroborating the results obtained herein.…”

Associations of acute phase protein levels with growth performance and with selection for growth performance in Large White pigs

“…The present study also observed the expected line differences in the food intake lines, but failed to observe line differences in growth rate in the lean growth lines in generation B. However, as described in the Material and methods section, these pigs were given a diet with lower energy content than those in the study reported by Cameron et al (2003), where the energy density of the diet was 14·0 MJ digestible energy per kg DM. Thus, although line differences in AGP were constant across the two generations and hence across diet, line differences in growth rate were affected by diet, possibly as a direct consequence of the difference in diet.…”

“…A recent publication describing contemporaneous pigs from these lines, including those from generation A in the 'lean growth under restricted feeding' lines, found line differences in food intake in the food intake lines, and also line differences in growth rate, with the high line from each selection criterion growing faster than the low line (Cameron et al, 2003). The present study also observed the expected line differences in the food intake lines, but failed to observe line differences in growth rate in the lean growth lines in generation B.…”

Heritability and genetic correlations of plasma metabolites of pigs with production, resilience and carcass traits under natural polymicrobial disease challenge

“…Typically, 95% of creatinine is found in muscle and an increase of creatinine concentration in blood is often considered as an indicator of kidney malfunction 27 . Conversion of muscle creatine into creatinine can reflect protein degradation 28 and serum creatinine concentration has been proposed as an indicator of protein deposition 29 . Animals with low ADG are expected to have lower protein or muscle deposition and our results suggest that increased plasma creatinine concentration might be a www.nature.com/scientificreports/ genetic indicator of low ADG in healthy nursery piglets.…”