Betaine and ractopamine for pigs from 90 to 140 kg

Abstract

Two experiments were carried out with female pigs from 90 to 140 kg. In experiment I, the objective was to evaluate the supplementation of ractopamine and betaine, alone or in association, on performance, carcass traits, meat quality and expression of genes related to lipid metabolism in skeletal glycolytic and oxidative muscle tissue and in the subcutaneous adipose tissue. In experiment II, to evaluate performance, carcass traits, pork quality and expression of genes related to lipid metabolism in glycolytic and oxidative muscle tissues of two divergent genetic lines fed ractopamine. In experiment I, a total of 72 female pigs (Agroceres PIC) with initial body weight of 88.96 ± 3.44 kg were assigned to a completely randomized design in four diets with nine replicates and two pigs per experimental unit, represented by the pen. Diets consisted of a control (CTRL) diet (without ractopamine and betaine); CTRL + 2.5 g/kg betaine (BET); CTRL+ 20 ppm ractopamine (RAC); and RAC + 2.5 g/kg de betaine (RAC + BET). In experiment II, eighteen female pigs Agroceres PIC 337 (Large White x Landrace x Duroc x Pietrain) x Camborough (Large White x Landrace) (HYB), with initial body weight of 88.96 ± 3.44 kg and 12 female pigs DB LQ 1250 (Duroc) x DB 90 (Large White x Landrace) (DUR), with initial body weight of 85.63 ± 1.55 kg were used. Pigs were allotted in a completely randomized design in two groups: HYB and DUR with nine and six replicates, respectively, and two pigs per experimental unit, represented by the pen. In experiment I, pigs fed RAC and RAC+BET diets had higher daily weight gain, lower feed conversion compared to pigs fed the other diets and higher hot carcass weight and carcass yield, compared to CTRL diet. Pigs fed BET, RAC and RAC+BET diets had greater loin muscle area. The backfat thickness was lower in pigs fed RAC+BET diet, compared to the CTRL. The meat from pigs fed BET diet had lower Warner-Bratzler shear force and higher percentage of intramuscular fat compared to CTRL. BET diet increased the expression of lipogenic factors in Longissimus dorsi and Soleus muscles compared to CTRL. In adipose tissue, RAC and BET diets increased the expression of genes related to lipolysis and β-oxidation. The results indicate that performance and carcass traits can be improved with ractopamine and betaine promotes increase in loin muscle area and pork quality. In experiment II, the performance of pigs from both genetic groups was similar. However, DUR pigs had lower backfat thickness. The meat from DUR pigs had higher L* (brightness), lower a* (redness) and higher percentage of intramuscular fat. DUR pigs had higher expression of peroxisome proliferator-activated receptor gamma (PPARγ) and fatty acid protein translocase/cluster differentiation (FAT/CD36), in addition to higher abundance of hormone-sensitive lipase (HSL) and Adiponectin (ADIP) mRNA in the Longissimus dorsi. Greater abundance of PPARγ and FAT/CD36 mRNA was also observed in the Soleus muscle of DUR pigs with no change in the expression of enzymes related to lipid degradation compared to HYB pigs. DUR pigs had carcasses with lower backfat thickness and better meat quality, evidenced by the higher percentage of intramuscular fat compared to HYB pigs. Possibly the higher concentration of intramuscular fat is mainly due to the higher expression of transcription factors and enzymes related to adipogenesis and lipogenesis in glycolytic and oxidative skeletal muscle tissue in DUR pigs. Keywords: Lipid metabolism. mRNA expression. Performance. Pork quality.