A study was conducted to evaluate the extent and dynamics of whole body protein deposition and changes in chemical and physical body composition after a period of AA intake restriction in growing barrows with medium lean tissue growth potentials. Forty Yorkshire barrows (initial BW 14.4 +/- 1.6 kg) were scale-fed at 75% of estimated voluntary daily DE intake up to 35 kg of BW and assigned to 1 of 2 diets: AA adequate (AA+; 20% above requirements; NRC, 1998) and AA deficient (AA-; 40% below requirements; restriction phase). Thereafter (re-alimentation phase), pigs from both dietary AA levels were scale-fed or fed ad libitum diets that were not limiting in AA. Body weight gain and body composition, based on serial slaughter, were monitored during the 34-d re-alimentation phase. During the restriction phase AA intake restriction reduced BW gains (556 vs. 410 g/d; P < 0.001; AA+ and AA-, respectively). At 35 kg of BW, AA intake restriction increased whole body lipid content (11.1 vs. 17.5% of empty BW; P < 0.05) and the whole body lipid to body protein ratio (0.65 vs. 1.20; P < 0.01) and reduced body protein content (17.1 vs. 14.6% of empty BW; P < 0.01) and body water content (68.2 vs. 63.9%; P < 0.05). The relationships between body protein vs. body water and body protein vs. body ash content were not altered by previous AA intake restriction or by feeding level during the re-alimentation phase (P > 0.10). Throughout the re-alimentation phase, there were no interactive effects of time, feeding level, and previous AA intake level on growth performance, body protein, and body lipid content (P > 0.10). During the re-alimentation phase, body protein deposition, derived from the linear regression analysis of body protein content vs. time, was not affected by feeding level and previous AA intake level (P > 0.10; 156 g/d for AA- vs. 157 g/d for AA+). Based on BW and body protein content, it can be concluded that no compensatory body protein deposition occurred in barrows, with medium lean tissue growth potential after AA intake restriction between 15 and 35 kg of BW. It is suggested that the upper limit to body protein deposition was the main factor that limited the extent of compensatory body protein deposition in this population of pigs. The concept of an upper limit to body protein deposition may be used to explain why compensatory growth is observed in some studies and not in others.

. 2008. Impact of feeding fermentable proteins and carbohydrates on growth performance, gut health and gastrointestinal function of newly weaned pigs. Can. J. Anim. Sci. 88: 271Á281. Feeding fermentable carbohydrates (FC) to weanling pigs may reduce the negative impact of proteolytic fermentation on gastrointestinal health and function. A total of 144 newly weaned pigs [6.23 kg body weight (BW); six pens per treatment; six pigs per pen) were used to determine the interactive effects of feeding additional fermentable protein (FP) and FC on growth performance, gastrointestinal function and intestinal health. Dietary treatments, based on a 2 )2 factorial arrangement, were: (1) basal diet (control); (2) control'10% poultry meal (PM) as FP source; (3) control'5% beet pulp (BP) as FC source; and (4) control'10% PM and 5% BP. Diets were formulated to be similar in digestible energy (DE) and digestible amino acid contents. In general, no interactive effects of FC and FP were observed (P0.10). During the 3-wk post-weaning period, feeding FP reduced average daily gain (ADG) (242 vs. 269 g d ; PB0.05). Overall, feed intake did not differ between treatments (P0.10). On days 14 and 28 post-weaning, Clostridia spp. counts in colon contents, counts of white cells and segmented neutrophils in blood were lowered (P B0.05) by feeding FC. Blood urea nitrogen was increased by feeding FP (9.5 vs. 6.5 mg dL (1 ; PB0.05), while ammonia concentration in colon contents was lowered by FC (154 vs. 193 mg mL (1 ) (P00.06). Among biogenic amines, levels of tyramine (140 vs. 304 nmol g(1 DM) and spermidine (174 vs. 219 nmol g(1 DM) in colon contents were lowered (P B0.05) by FC. Acetic, proprionic and butyric acid contents in colon contents were increased by feeding FC, while valeric and caproic acid content decreased by feeding FP (PB0.05). Feeding FC and FP had no effect (P0.10) on colon histology, pH, fecal consistency score and organ weights. Results suggest that FP and FC have independent effects on newly weaned pigs, while effects appear partly related to changes in gut microbiota.

A study was conducted to evaluate the extent and dynamics of whole body protein deposition (Pd) and changes in chemical and physical body composition after a period of AA intake restriction in entire male pigs with high lean-tissue growth potentials. Fifty-eight entire male pigs (initial BW 15.8 +/- 0.9 kg) were allotted to 1 of 3 dietary AA levels between 15 and 38 kg of BW: control (15% above requirements), AA-15% (15% below requirements), and AA-30% (30% below requirements). Thereafter, pigs were fed diets not limiting in AA content. Throughout the experiment, pigs were scale-fed at 90% of estimated voluntary daily DE intake. Representative pigs were slaughtered at 15, 38, 53, 68, or 110 kg of BW to monitor changes in body composition. Between 15 and 38 kg of BW, restriction of AA intake reduced BW gain (P < 0.01; 794, 666, and 648 g/d for control, AA-15%, and AA-30%, respectively). At 38 kg of BW, AA intake restriction increased whole body lipid (LB) content (P < 0.01; 11.3, 14.3, 17.5% of empty BW), and the LB-to-whole body protein (PB) ratio (LB/PB; P < 0.02; 0.68, 0.88, 1.10 for control, AA-15%, and AA-30%, respectively). Relationships between PB versus whole body water and PB versus whole body ash were not affected by dietary treatments (P > 0.10). At 110 kg of BW and based on BW, PB, and LB/PB, complete compensatory growth (CG) was achieved. Body weight gain between 38 and 110 kg of BW was inversely related to previous dietary AA levels (P < 0.01; 1,089, 1,171, and 1,185 g/d for control, AA-15%, and AA-30%, respectively). For pigs on the control diet, and based on N-balance data, Pd increased with BW, from 172 g/d at 40 kg of BW to 226 g/d at 82 kg of BW. At 40 kg of BW, Pd was greater (P < 0.05) for pigs on the AA-15% (205 g/d) and AA-30% (191 g/d) diets than pigs on the control diet (172 g/d). These findings indicate that pigs with high lean-tissue growth potentials are more likely to express compensatory Pd and their genetically determined upper limit to Pd (PdMax) after a period of AA intake restriction. This study confirms previous findings that BW effects on PdMax are small in growing pigs between 40 and 80 kg of BW. It is suggested that CG and compensatory Pd after a period of AA intake restriction is constrained by the pig's PdMax and is driven by a target LB/PB. Combined with previous observations in our laboratory, these results suggest that CG after a period of AA intake restriction tends to occur only when pigs are within the energy-dependent phase of lean-tissue growth and not when the genetically determined upper limit to lean-tissue growth, or PdMax, determines growth performance.

. 2002. Digestible energy and amino acid contents in Canadian varieties of sorghum, pearl millet, high-oil corn, high-oil-high-protein corn and regular corn samples for growing pigs. Can. J. Anim. Sci. 82: 385-391. Fecal digestible energy (DE) and ileal digestible crude protein (CP) and amino acid (AA) contents in sorghum, pear millet, high-oil corn, high-oil-high-protein corn, regular corn I and II were determined in growing pigs fitted with ileal "T" cannulas. The cereal grain samples were grown in Canada and supplemented with vitamins and minerals to produce six experimental diets. Six pigs, with an average initial body weight of 17 kg, were fed the diets during six subsequent experimental periods according to a Latin square design. Pigs were fed twice daily at 2.6 times maintenance energy requirements. After a 7-d adjustment period, feces were collected for 3 d, followed by a 48-h collection of ileal digesta. Apparent and standardized ileal AA digestibilities were calculated. The high-oil corn and high-oil-high-protein corn had the highest (P < 0.05) DE content [4029, 4048 kcal kg -1 dry matter (DM), respectively]. The sorghum had a higher (P < 0.05) DE content (3941 kcal kg -1 DM) than pear millet (3603 kcal kg -1 DM) and regular corn I (3710 kcal kg -1 DM basis) and similar DE content to regular corn II (3945 kcal kg -1 DM). Contents of standardized ileal digestible CP and AA varied between cereal grains were generally highest (P < 0.05) for PM (CP: 101.6 g kg -1 DM; lysine, methionine plus cysteine, threonine: 3.4, 4.8 and 4.3 g kg -1 DM, respectively), HOPC (CP: 100.9 g kg -1 DM; lysine, methionine plus cysteine, threonine: 3.1, 5.4 and 4.3 g kg -1 DM, respectively) and similar for the other cereal grains (CP: 94.1-98.4 g kg -1 DM; lysine, methionine plus cysteine, threonine: 2.6-3.0, 3.4-4.3 and 3.3-4.0 g kg -1 DM, respectively). Differences in feeding values of these cereal grains should be considered when evaluating their potential inclusion in pig diets. Abbreviations: AA, amino acid; ADF, acid detergent fiber; AFD, apparent fecal digestibility; AID, apparent ileal digestibility; CP, crude protein; DE, digestible energy; DM, dry matter; GE, gross energy; NDF, neutral detergent fiber Can. J. Anim. Sci. Downloaded from www.nrcresearchpress.com by 54.191.190.102 on 05/11/18For personal use only.

In this experiment, we assessed the effect of amino acid (AA) intake restriction in entire male Yorkshire pigs between 15 and 38 kg BW (restriction phase) on BW gain, body composition and plasma levels of blood urea nitrogen (BUN), cortisol, insulinlike growth factor I (IGF-I), growth hormone (GH) and leptin during the subsequent re-alimentation phase. During the restriction phase, 36 pigs were allotted to one of two dietary treatments: adequate AA intake (control) or AA-limiting diets (AA-30%). Thereafter, pigs were fed common non-limiting diets up to 110 kg BW. Throughout the experiment, pigs were scale-fed at 90% of the estimated voluntary daily digestible energy intake. At the end of the restriction phase, pigs on AA-30% had lesser BW gain (650 v. 784 g/day; P , 0.001), loin area (LA; 12.2 v. 14.2 cm 2 ; P , 0.001), BUN (4.6 v. 6.3 mg/dl; P , 0.02), lesser plasma levels of IGF-I (440 v. 640 ng/m; P , 0.001) and cortisol (8.2 v. 19.2 mg/dl; P , 0.001), greater backfat thickness (BF; 7.56 v. 6.56 mm; P , 0.02), and greater plasma levels of leptin (2.7 v. 1.8 ng/ml; P 5 0.027) and GH (3.3 v. 2.0 ng/ml; P 5 0.05) than pigs on control. During the re-alimentation phase, previously restricted pigs showed full compensatory growth (CG) in terms of BW gain (1170 v. 1077 g/day; P , 0.002), whole-body protein deposition (Pd) (179 v. 163 g/day; P , 0.001) as well as physical and chemical body composition (whole-body lipid to body protein mass ratio, LB/PB; 1.14 v. 1.15; P . 0.10). Besides GH at 45 kg BW (4.2 v. 2.4 ng/ml; P 5 0.066), there were no effects of previous AA intake restriction on leptin, IGF-I and BUN during the re-alimentation phase ( P . 0.10). Plasma cortisol and IGF-I levels may act as an indicator of AA-induced restriction in Pd in growing pigs. Plasma BUN level does not appear as a sensitive indicator for compensatory Pd. Plasma leptin and GH levels allow for the involvement of the brain in controlling chemical body composition. Full CG was observed during the energydependent phase of Pd in growing pigs and might be driven by a target LB/PB, possibly mediated via plasma leptin, IGF-I and GH levels.