Amino acid release patterns of growing pig diets formulated with different dietary protein sources

Relationship between dietary amino acid release kinetics and nitrogen deposition in growing pigs

Although the protein content of swine diets is formulated based on the ileal digestibility of protein and amino acids (AA) under current nutrition requirements, the nitrogen utilization efficiency of swine varies based on protein source, which may be related to AA release kinetics. In this experiment, a 2 × 2 factorial arrangement with casein (CAS)-enriched or corn gluten meal (CGM)-enriched protein sources at different digestible crude protein levels (normal [N], 13%; and low [L], 11%) were applied to 24 crossbred (Duroc × Landrace × Yorkshire) growing pigs (average body weight = 43.3 ± 3.5 kg) in 4 treatments (N.CAS, L.CAS, N.CGM, L.CGM, respectively) to investigate the effects of AA release kinetics on nitrogen deposition in growing pigs. Standardized ileal digestible AA in all diets were balanced by adding individual AA to meet the nutrient requirements. The AA release kinetics were detected in vitro by measuring the hydrolysis of various protein diets under pepsin and trypsin conditions. The results demonstrated that the time of AA release peak in the CGM diet was 12 h later than that in the CAS diet. The synchronization indices of dietary AA release in N.CAS, N.CGM, L.CAS, and L.CGM were 23.73%, 29.37%, 23.40%, and 26.07%, respectively. The N.CGM had the poorest AA release synchronism while the N.CAS had the greatest among the 4 diets. However, within the pigs, L.CAS and N.CGM showed the highest (81.08%) and lowest (73.54%) nitrogen biological values, respectively, despite the standard ileal digestible AA levels being equal for all diets. These results indicate that the release kinetics of dietary AA had great effect on nitrogen deposition. To optimize nitrogen deposition, AA release kinetics and composition should be taken into consideration when formulating diets for growing pigs.

Effects of Lactobionic Acid on Pig Growth Performance and Chemical Composition of Pork

Lactobionic acid is an innovative product obtained in the fermentation process of cheese or curd whey, and it has several beneficial properties. Therefore, it may have potential application in animal feeding. Currently, lactobionic acid is not widely used yet in feeding farm animals. Therefore, the aim of our study was to evaluate the effect of lactobionic acid (LBA) on pig growth performance and pork quality. Two groups of pigs (control and trial, 26 piglets each) were completed. The control group received compound feed, whereas the trial group's feed was supplemented with LBA (0.17 kg per 100 kg of feed). Carcass weight and meat pH were determined. The subcutaneous fat layer S (mm) was measured. Lean meat content was determined using the SEUROP classification. Amino acids and fatty acids in pork were evaluated. The addition of LBA to pig feed significantly increased the live weight gain and slaughter yield of pigs, but the samples had a slightly thicker backfat layer. Results obtained showed higher concentration of amino acids in the trial group but slightly lower pork fat quality in the same group. Lactobionic acid has the potential for applications in pig feeding.

Effects of protein content and the inclusion of protein sources with different amino acid release dynamics on the nitrogen utilization of weaned piglets

Objective

We aimed to investigate the effect of the differing amino acid (AA) release dynamics of two protein sources on the growth performance, nitrogen deposition, plasma biochemical parameters, and muscle synthesis and degradation of piglets when included in their diets at normal and low concentrations.

Methods

Forty-eight piglets (Duroc×Landrace×Large White) with initial body weight of 7.45±0.58 kg were assigned to six groups and fed one of 6 diets. The 6 dietary treatments were arranged by 3 × 2 factorial with 3 protein sources and 2 dietary protein levels. They are NCAS (a normal protein content with casein), NBlend (a normal protein content with blend of casein and corn gluten meal), NCGM (a normal protein content with corn gluten meal), LCAS (a low protein content with casein), LBlend (a low protein content with blend of casein and corn gluten meal), LCGM (a low protein content with corn gluten meal). The release dynamics of AA in these diets were determined by in vitro digestion. The digestibility, utilization and biological value of nitrogen in piglets were determined by micro Kjeldahl method. Plasma insulin was measured by ELISA kits. The protein expression of mediators of muscle synthesis and degradation was determined by western blotting.

Results

Although the consumption of a low-protein diet supplemented with crystalline AA was associated with greater nitrogen digestion and utilization (p<0.05), the final body weight, growth performance, nitrogen deposition, and phosphorylation of ribosomal protein S6 kinase 1 and eIF4E binding protein 1 in the muscle of pigs in the low-protein diet-fed groups were lower than those of the normal-protein diet-fed groups (p<0.05) because of the absence of non-essential AA. Because of the more balanced release of AA, the CAS and Blend-fed groups showed superior growth performance, final body weight and nitrogen deposition, and lower expression of muscle ring finger 1 and muscle atrophy F-box than the CGM-fed groups (p<0.05).

Conclusion

We conclude that the balanced release of AA from CAS containing diets and mixed diets could reduce muscle degradation, favor nitrogen retention, % intake and improve growth performance in pigs consuming either a normal- or low-protein diet.