Soybean molasses increases subcutaneous fat deposition while reducing lipid oxidation in the meat of castrated lambs.

This study aimed to evaluate the effect of including soybean molasses (SM) on performance, blood parameters, carcass traits, meat quality, fatty acid, and muscle (longissimus thoracis) transcriptomic profiles of castrated lambs. Twenty Dorper × Santa Inês lambs (20.06 ±â€…0.76 kg body weight [BW]) were assigned to a randomized block design, stratified by BW, with the following treatments: CON: 0 g/kg of SM and SM20: 200 g/kg of SM on dry matter basis, allocated in individual pens. The diet consisted of 840 g/kg concentrate and 160 g/kg corn silage for 76 d, with the first 12 d as an adaptation period and the remaining 64 d on the finishing diet. The SM20 diet increased blood urea concentration (P = 0.03) while reduced glucose concentration (P = 0.04). Lambs fed SM showed higher subcutaneous fat deposition (P = 0.04) and higher subcutaneous adipocyte diameter (P < 0.01), in addition to reduced meat lipid oxidation (P < 0.01). SM reduced the quantity of branched-chain fatty acids in longissimus thoracis (P = 0.05) and increased the quantity of saturated fatty acids (P = 0.01). In the transcriptomic analysis, 294 genes were identified as differentially expressed, which belong to pathways such as oxidative phosphorylation, citric acid cycle, and monosaccharide metabolic process. In conclusion, diet with SM increased carcass fat deposition, reduced lipid oxidation, and changed the energy metabolism, supporting its use in ruminant nutrition.

This study investigated the effects of incorporating soybean molasses (SM) into the diet of castrated lambs on various aspects of their performance and meat quality. Twenty lambs were divided into two groups: one was fed a control diet without SM whereas the other was fed a similar diet but containing 20% of SM. The feeding trial lasted for 76 d. Results showed that the SM inclusion in the diet led to increased blood urea levels and decreased glucose concentrations. SM inclusion also resulted in lambs with higher levels of subcutaneous fat and larger adipocytes, while reducing meat lipid oxidation. Moreover, SM altered fatty acid composition in the meat, decreasing branched-chain fatty acids and increasing saturated fatty acids. In agreement with these findings, transcriptomic analysis revealed a significant change in the expression of genes related to energy metabolism in the muscle of lambs fed SM. In conclusion, incorporating SM in lamb's diet increased fat deposition, improved meat quality, and induced a transcriptomic change in the muscle energy metabolism, supporting its potential use in ruminant nutrition.

Effect of growth hormone on fatty acid synthase gene expression in porcine adipose tissue cultures

We describe an efficient in vitro assay to test growth hormone effects on mRNA levels and fatty acid synthase (FAS, EC. 2.3.1.85) activity. Swine adipose tissue explants were long-term cultured in medium containing growth hormone and FAS mRNA levels and enzyme activity were measured. We quantified FAS transcripts by competitive reverse transcriptase PCR (RT-PCR) using total RNA from cultured adipose tissue explants and RT-PCR standard-curves were constructed using a cloned 307 bp segment of native FAS cDNA and a shorter fragment from which a 64 bp (competitor, 243 bp) internal sequence had been deleted. A known amount of competitor was added to each PCR as an internal control and æ-actin transcripts were also measured to correct for differences in total RNA extraction and reverse transcription efficiency. In cultures with added growth hormone FAS mRNA levels decreased 70 percent (p < 0.01) and FAS enzyme activity decreased 22 percent (p < 0.05). These in vitro growth hormone effects were consistent with those observed in vivo, showing that in vitro adipose tissue culture combined with RT-PCR is a useful and accurate tool for studying growth hormone modulation of adipose tissue metabolism. This technique allowed the diagnosis of lower levels of FAS mRNA in the presence of growth hormone and these low levels were associated with decreased FAS activity in the adipose tissue explants.