No abstract

Zilpaterol hydrochloride (ZH) redistributes ingested energy and improves feed efficiency by increasing muscle mass and reducing fat in sheep and cattle carcasses in fattening; however, by increasing lipolysis and reducing intramuscular fat (IMF), it can affect meat quality in terms of the attributes of tenderness, juiciness, taste and color; in contrast, Zn methionine (ZM), due to its lipogenic effect, can improve meat marbling without affecting production efficiency. In the current study, 36 male Suffolk sheep were used (25 ± 0.58 kg live weight, LW) to evaluate the supply of ZH and ZM on growth, carcass traits, meat quality, fatty acid content and expression of genes which regulate the deposition of fatty acids (FA) in IMF. A completely randomized design was used, with factorial arrangement of 2 × 2 ZH (0 and 0.2 mg kg−1 LW) and ZM (0 and 80 mg Zn kg−1 dry matter, DM). The results showed that ZH increased (p < 0.05) carcass yield, compactness index and chop eye area and decreased greasing (p < 0.02). The content of ether extract in meat increased (p < 0.05) in sheep with ZM plus ZH, and in sheep with ZM (p < 0.01). ZH (p < 0.05) reduced (p < 0.02) the meat’s color index L*, a*, b*, C* and H*. The content in IMF of stearic (C18:0) and arachidic (C20:0) FA was reduced (p ≤ 0.05) by the effect of ZH, but the palmitoleic (C16:1), eicosatetraenoic (C20:4n6) and conjugated linoleic FA were increased (p ≤ 0.05) by the effect of ZH. ZM increased (p ≤ 0.05) palmitoleic (C16:1) and conjugated linoleic FA; the ZH interaction with ZM increased (p ≤ 0.05) linoleic (C18:2 c 9 c 12), linolenic (C18:3 c 9c12c15) and eicosatetraenoic (C20:4n6) FA. The ZH interaction with ZM influenced (p ≤ 0.05) the total saturated fatty acids (SFA), unsaturated fatty acids (UFA) and polyunsaturated fatty acids (PFA). ZH increased (p ≤ 0.05) the relative expression of mRNA from the enzymes lipoprotein lipase (LPL), hormone-sensitive lipase (HSL), glycerol -3-phosphate acyltransferase (GPAT1) and diglyceride acyltransferase (DGAT1). ZM increased (p ≤ 0.05) the relative expression of mRNA from the enzyme gene acetyl-CoA carboxylase (ACC) and HSL, monoglyceride lipase (MGL). The ZM interaction with ZH increased (p ≤ 0.05) the relative expression of mRNA genes of the enzymes HSL and ACC. It was concluded that ZH improved feed conversion (FC), increased yield and reduced fat in carcasses; ZM increased IMF in Longissimus dorsi. ZH and ZM influenced the FA composition, reduced the SFA and increased the UFA and PFA; both additives also influenced the relative mRNA expression of genes involved in fatty acid metabolism.

No abstract

<p>The objective was to evaluate the effect of including 0, 75, 150 and 225 mg Cu kg^-1 MS of copper proteinate (P-Cu) in the feed on growth, carcass characteristics and meat quality of pigs for market. Twenty four pigs (12 females and 12 males) were used, initial weight 60.3±0.55 kg, fed with basal diet (BD) during 46 days, distributed in a completely randomized design, factorial 4x2 (levels of P-Cu and sex): T1=DB (0 mg of P-Cu kg-1 MS), T2=DB+75 mg of P-Cu, T3=DB+150 mg of P-Cu and T4=DB+225 mg of P-Cu. The dose of 225 mg of P-Cu increased the daily weight gain (DWG) and the feed efficiency (FE) (P&lt;0.05). The P-Cu increased the area of chop (CHA) in females and reduced the back fat (BF) in males (P&lt;0.05). The P-Cu increased (12.6%) the yield of primary cuts (YPC) (P&lt;0.05). In treatments 3 and 4 the water loss was reduced 58.5 and 82.2% (P&lt;0.05). The P-Cu affected (P&lt;0.01) the final pH and the a* index (P&lt;0.05) of the <em>Longissimus thoracis</em> muscle. In conclusion, the P-Cu improved the DWG, the FE, the CHA and the YPC, and reduced the BF in the carcass.</p>

Rodríguez-Gaxiola (2020) Effects of dietary chromiumyeast level on growth performance, blood metabolites, meat traits and muscle fatty acids profile,