Zinc (Zn) is a micromineral with structural, catalytic, and regulatory functions in muscle tissue. It improves growth in ruminants because it modulates energy metabolism. The objective of this study was to evaluate the effect of Zn methionine (Zn-Met) and (or) Zn oxide (ZnO) addition in the diet of Katahdin × Dorper lambs on performance, carcass traits, and meat quality characteristics. Forty non-castrated Katahdin × Dorper F1 lambs were randomly assigned to the following experimental groups: (1) Zn-Met (65 ppm), (2) ZnO (65 ppm), (3) Zn-Met + ZnO (32.5 + 32.5 ppm), and (4) basal diet (BD, without Zn). The duration of experiment was 93 d. Treatment Zn-Met + ZnO vs. control improved (P ≤ 0.05) average daily gain (ADG) and feed conversion (FC); ZnO increased leg perimeter and decreased visceral fat. Intramuscular fat (IMF) and marbling of chop with Zn-Met + ZnO vs. control were higher (P ≤ 0.05). Oxidative stability of cooked meat was delayed (P ≤ 0.05) with Zn-Met + ZnO. Myristic acid was lowest (P ≤ 0.05) with ZnO, and arachidonic acid was higher (P ≤ 0.05) in Zn-Met. Therefore, compared with the BD, Zn-Met + ZnO improved the ADG and FC, decreased the shear force, and delayed the stability oxidative in cooked meat; Zn-Met and ZnO increased the IMF and marbling; additionally, Zn-Met increased arachidonic acid and ZnO decreased visceral fat and myristic acid.

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.

Nutritive value of ensiled pig excreta, poultry litter or urea with molasses or bakery by-products in diets for lambs

This research was carried out to determine the effect of corn stover silage with three non-protein nitrogen sources plus two carbohydrate sources on its mineral content. Nitrogen sources (NS) were agricultural urea (AU), dehydrated poultry litter (PL) and swine manure fresh (SM); and those of carbohydrates (CS) sugar cane molasses (SCM) and bakery by-products (BBP). After 30 d of fermentation, the microsilages were opened and the concentration of Ca, P, Na, K, Mg, Co, Cu, Mn, Fe, and Zn were measured. The results were subjected to analysis with a completely randomized design with a 3×2 factorial arrangement of treatments and under a mixed effects model. There were (P<0.01) NS×CS interactions on the mineral content of all silages. The PL+SCM silage was higher (P<0.01) in Ca, P, Na, Mg and K. The SM silage had higher (P<0.01) Cu content, and the PO-based treatments had higher (P< 0.01) Mn content. In general, the highest mineral content was observed in silages based on PL and SM. It is concluded that corn stover silage enriched with PL with SCM can provide macro and micro minerals in ruminant feed. http://dx.doi.org/10.21929/abavet2023.17 e2022-51 https://www.youtube.com/watch?v=IiFE9CBmF48 Esta investigación se realizó para determinar el contenido mineral del ensilado de rastrojo maíz con tres fuentes de nitrógeno no proteico y dos fuentes de carbohidratos. Las fuentes de nitrógeno (NS) fueron urea agrícola (UA), pollinaza deshidratada (PO) y cerdaza fresca (CF); y las fuentes de carbohidratos (CS) fueron melaza de caña y subproductos de panadería. Después de 30 d de fermentación, los microensilados se abrieron y se midió la concentración de Ca, P, Na, K, Mg, Co, Cu, Mn, Fe, y Zn. Los resultados fueron sujetos a análisis con un diseño completamente al azar con arreglo factorial 3×2 y modelo de efectos mixtos. Hubo interacciones (P<0.01) NS×CS sobre el contenido mineral de todos los ensilados. El ensilado PO+MC fue mayor (P<0.01) en Ca, P, Na, Mg y K. Los ensilados con CF tuvieron mayor (P<0.01) contenido de Cu, y los tratamientos a base de PO tuvieron mayor (P<0.01) contenido de Mn. En general, los mayores contenidos de minerales se observaron en ensilados a base de PO y CF. Se concluye que el ensilado de rastrojo de maíz enriquecidos con PO con MC puede proveer macro y microminerales en la alimentación de rumiantes. http://dx.doi.org/10.21929/abavet2023.17 e2022-51 https://www.youtube.com/watch?v=IiFE9CBmF48 http://dx.doi.org/10.21929/abavet2023.17 e2022-51 https://www.youtube.com/watch?v=IiFE9CBmF48

Background: The use of silages from non-conventional sources of nitrogen and soluble carbohydrates in feeding lambs is controversial in terms of nutrient supply; due to the minimum number of studies reported to date of in vitro evaluations that allow measuring its nutritional value in ruminants. Objective: To evaluate the additive effect and fermentation potential of silages plus concentrates in diets for lambs on the in vitro gas production kinetics. Methodology: Six diets (silage + concentrate) were evaluated in a factorial arrangement of 3 N sources (dried poultry litter, fresh swine manure, agricultural urea) × 2 carbohydrate sources (sugar cane molasses, bakery by-product). The diets contained: a) silage (400 g/kg DM) and b) concentrates (600 g/kg DM) based on soybean meal, ground corn, wheat bran, corn stover, fish meal, and vitamin and mineral premix. Average gas production data were analyzed with PROC MIXED and the gas production curves were fitted into the Exponential Logistic model with PROC NLMIXED. Results: The PO+MC (151.87 mL/gas MS) and CF+MC (153.12 mL/gas MS) treatments had higher average gas production during incubation. An additive effect was observed on the maximum asymptote of gas production in the CF+MC (+ 4.26%) and PO+MC (+ 3.75%) diets (P<0.01). Diets based on PO or CF combined with MC and SPP had higher IVDMD, IVOMD, and IVNDFD than the control treatment (UR). Implications: The inclusion in diets for growing lambs of corn stover silage based on rapidly fermentable carbohydrate sources with non-protein nitrogen from pig and poultry excreta in diets for growing lambs has associative effects on nutrient degradability and its fermentation potential in small ruminant feed. Conclusions: The PO+MC treatment has a higher potential for gas production due to the associative effect of its components.