The present study aimed to evaluate the effect of copra meal (the waste coconut of the oil industry) on in vitro ruminal kinetic and greenhouse gases production and on in vivo lamb performance. Twenty-eight male Rambouillet sheep (initial body weight 24.5 ± 3.9 kg) were randomly assigned to one of the four treatments: 0, 50, 100, and 150 g of copra meal/kg in their diet (dry matter basis). Final weight, weight gain, and feed intake were not affected (p > 0.05) by the copra meal addition. The gas production volume (V) decreased, and the gas production rate increased, in a linear trend (p < 0.05) as copra meal was added to the diet. In contrast, methane and CO₂ production showed an opposite quadratic trend (p < 0.05), with the highest and lowest values reported at 100 g/kg DM of copra meal, respectively. The addition of copra meal in the lambs’ diet decreases the volume of gas production and is a strategy to decrease methane and carbon dioxide production in feeding without affecting animal performance.

To determine the effect of adding β2 agonist zilpaterol hydrochloride during different periods on growth performance, dietary energetic, carcass traits and fatty acid profile, forty male lambs Pelibuey × Katahdin (37.70 ± 0.83 kg) were blocked by body weight and randomly assigned to pens. Treatments consisted in: 1) control, no zilpaterol supplementation, 2) zilpaterol supplementation for 20 d (ZIL20), 3) zilpaterol supplementation for 30 d (ZIL30), and 4) zilpaterol supplementation for 40 d (ZIL40). Compared with control treatment, zilpaterol supplementation increased final live weight (FLW) (3.5 %; P = 0.0563), average daily gain (ADG, 14.8 %; P = 0.0598) and gain:feed ratio (10.3 %; P = 0.0324). As well as hot carcass weight (6.1 %; P = 0.0064), dress out percentage (2.6 %; P = 0.0139) and Longissimus dorsi muscle area (13.7 %; P = 0.0015). Compared to control group, zilpaterol increased (P = 0.0413) observed vs. expected dietary of NEm (net energy requirements for maintenance) and NEg (net energy requirements for growth) (5.7 and 8.1 %, respectively). Twenty days of zilpaterol treatment improved FLW (4.4 %, P = 0.0566) and tended to improve ADG (17.4 %, P = 0.0718) when compared to control group. Only intramuscular fat showed a positive linear effect (P = 0.0006) in stearic fatty acids proportion and negative linear effect (P = 0.0585) in araquidonic fatty acid proportion. We conclude that zilpaterol hydrochloride improved variables of growth performance, energy retention and carcass traits with noticeable effects from 20 d of zilpaterol supplementation.

This study evaluated the impact of supplementing ZH in combination with D3 on the growth performance, energy efficiency, carcass traits, and meat quality of feedlot lambs. Thirty-two Dorper × Katahdin cross lambs (37.3 ± 5.72 kg) were utilized in a 29 d experiment in a completely randomized block design with a 2 × 2 factorial structure consisting of two levels of ZH for 26 d (0 and 0.20 mg/kg PV⁻¹) and two levels of D3 for 7 d (0 and 1.5 × 10⁶ IU/d⁻¹). ZH improved (p ≤ 0.05) the average daily gain (ADG) and feed efficiency by 9.9% and 17.8%, respectively, as well as hot carcass weight (HCW) and dressing carcass by 4.3% and 2.6%, respectively. (p ≤ 0.03). However, ZH increased (p < 0.01) muscle pH and Warner–Bratzler shear force (WBSF) (2.5 and 23.0%, respectively). D3 supplementation negatively affected (p ≤ 0.02) dry matter intake (DMI) (last 7 d) and ADG by 15.7% and 18.1%. On the other hand, D3 improved the pH of the longissimus thoracis muscle by 1.7% (p = 0.03) without affecting WBSF. When D3 was supplemented in combination with ZH, it was observed that meat quality was improved by reducing muscle pH compared to lambs treated only with ZH. However, D3 did not improve the meat tenderness negatively affected by ZH supplementation.

The objective of this study was to evaluate the effects of zilpaterol hydrochloride supplementation strategies on growth performance, dietary energetics, carcass traits, and meat quality in feedlot finishing lambs. Twenty-four Dorper × Katahdin crossbred male lambs (45.5 ± 4.53 kg, mean ± SD) were used in a 27 d feeding trial. The zilpaterol supplementation strategies were: (1) control, no zilpaterol supplementation (CON); (2) zilpaterol administered once daily as a full dose in the morning feeding (ZMOR); (3) zilpaterol incorporated into the total mixed ration and continuously available throughout the day (ZMIX); and (4) intermittent zilpaterol supplementation applied in a daily alternating pattern, one day on, one day off (ZINT). A target dose of 0.20 mg/kg live weight of zilpaterol hydrochloride per administration was used for all supplemented treatments, with daily administration in ZMOR and ZMIX and alternate-day administration in ZINT. Compared to the CON, zilpaterol supplementation through the ZMOR + ZMIX strategies improved average daily gain (ADG) and feed efficiency (FE) by 28.6% and 18.5%, respectively. Additionally, dressing percentage and longissimus thoracis muscle area increased by 3.2% and 17.0%, respectively. The ZINT strategy also enhanced ADG by 20.9% and FE by 15.4%. However, ZINT did not improve hot carcass weight or dressing percentage. All zilpaterol supplementation strategies increased meat toughness by up to 39.2%. Results indicate that both the ZMOR and ZMIX strategies optimize the response to zilpaterol, with no evidence that ZMOR supplementation results in a diminished response.

The study evaluated the impact of supplementing ZH in combination with D3 on growth performance, energy efficiency, carcass traits, and meat quality of feedlot lambs. Thirty-two Dorper x Katahdin cross lambs (37.3±5.72 kg) were utilized in a 29 d experiment in a complete randomized block design with a 2x2 factorial structure consisting of two levels of ZH for 26 d (0 and 0.20 mg /kg PV-1) and two levels of D3 for 7 d (0 and 1.5x106 IU/d-1). ZH improved (P≤0.05) average daily gain (ADG) and feed efficiency by 9.9% and 17.8%, respectively, as well as hot carcass weight (HCW) and dressing carcass by 4.3% and 2.6%, respectively. (p≤0.03). However, ZH increased (p<0.01) muscle pH and Warner-Bratzler shear force (WBSF) (2.5 and 23.0%, respectively). D3 supplementation negatively affected (P≤0.02) dry matter intake (DMI) (last 7 d) and ADG by 15.7% and 18.1%. On the other hand, D3 improved the pH of the longissimus muscle (LM) by 1.7% (p=0.03) without affecting WBSF. When D3 was supplemented in combination with ZH, it was observed that meat quality was improved by reducing muscle pH compared to lambs treated only with ZH. However, D3 did not improve meat tenderness produced by ZH supplementation.

The objective of this research was to identify the tree species used in feeding cattle, as well as their density and nutritional value in Sinaloa, Mexico. The study was carried out through monthly samplings and a survey to producers. The variables evaluated were Dry Matter (DM), Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF), Cellular Content (CC), Potential Dry Matter intake (PDMI), Digestible Energy (DE), Net Energy for maintenance (NEm), Net Energy forgain (NEg), Net Energy for lactation (NEl), Total Digestible Nutrients (TDN) and Growing Degree Days (GDD). The results showed the following order of tree consumption preference by cattle: (1) Lysiloma divaricatum, (2) Acacia farnesiana, (3) Ebenopsis ebony, (4) Tabebuia rosea, (5) Guazuma ulmifolia and (6) Chloroleucon mangense Jacq. The NDF content was the highest in Tabebuia rosea (54.4%) as well as in ADF (42.8%) and Ebenopsis ebano was the lowest (19.3%). The highest content was observed in Ebenopsis ebano (4.9%) and Acacia farnesiana (3.7%). The highest NEl content was observed in Tabebuia rosea (1.99 Mcal/kg DM), and the lowest in Guazuma ulmifolia (1.26 Mcal/kg DM). Ebenopsis ebano showed, the highest content was observed in NEl (1.86 Mcal/kg DM) and the lowest was observed in Tabebuia rosea (1.22 Mcal/kg DM). A significant difference (P<0.05) was observed in the accumulation of average GDD per day by forage species. Acacia farnesiana is the forage tree with the highest consumption by cattle and the one that presented the highest density in the sampled area. Chloroleucon mangense is the second most important species, despite its low density in the study area. GDD were higher in the summer season, while the lowest amount occurred in autumn, which was reflected in differences in the quality and quantity of the forage.