Influences of a Supplemental Blend of Essential Oils Plus 25-Hydroxy-Vit-D3 and Zilpaterol Hydrochloride (ß2 Agonist) on Growth Performance and Carcass Measures of Feedlot Lambs Finished under Conditions of High Ambient Temperature.

Forty-eight Pelibuey × Katahdin male intact lambs (25.12 ± 3.79 kg LW) were used in a 70-d growing-finishing trial. Dietary treatments consisted of total mixed corn-based diet supplemented with: (1) no feed additives (Control); (2) 150 mg of essential oils blend plus 0.10 mg of 25-hydroxy-Vit-D3/kg diet offered throughout the 70-d experimental period (EOD3); (3) Control diet fed during the first 35 days and zilpaterol hydrochloride (ZH) supplementation at 6 mg/kg diet offered during the final 35 days of the experiment (32 days with ZH with a withdrawal 3-d before harvest), and (4) basal diet supplemented with EOD3 during first 35 days finishing, and EOD3 in combination with ZH (EOD3 + ZH) during the subsequent 32-days with ZH withdrawal 3 days before harvest. The temperature-humidity index during the experiment averaged 80.4 ± 3.2. There were no treatment interactions (p > 0.20) on growth performance and carcass measures. Supplemental EOD3 did not affect (p = 0.43) dry matter intake (DMI), but increased (p < 0.01) carcass adjusted average daily gain (ADG, 9.2%), gain efficiency (GF, 6.7%), and observed vs. expected dietary net energy for maintenance (NEm, 4.8%) and for gain (NEg, 6.4%). Supplemental ZH did not affect dry matter intake (DMI, p = 0.50) but increased (p < 0.01) carcass adjusted ADG (14.5%), GF (13%) and observed vs. expected dietary NEm (9%) and NEg (11.7%). Compared to control lambs, the combination of both additives increased ADG (24.9%), GF (21.2%), and observed vs. expected dietary NEm and NEg (14.2% and 18.9%, respectively). There were no treatment interactions on carcass characteristics, visceral organ mass, or on gene expression of IGF1, IGF2 and mTOR in longissimus muscle (LM). Supplemental EOD3 increased hot carcass weight (HCW; 4.0%, p < 0.01) but did not affect other carcass measures. Supplemental EOD3 decreased (3%, p = 0.03) intestine mass weight (g intestine/kg empty body weight). Supplemental ZH increased HCW (6%, p < 0.01), dressing percentage (1.7%, p = 0.04), and LM area (9.7%, p < 0.01), and decreased kidney-pelvic-fat percentage (16.2%, p < 0.01), fat thickness (14.7%, p = 0.03), and visceral fat. Compared to controls, the combination of EOD3 with ZH increased HCW (10.2%). It is concluded that growth performance responses to supplemental EOD3 and ZH are additive. Both supplements can be fed in combination without detrimental effects on expected benefits when fed separately. In addition, ZH supplementation improves carcass traits.

Effect of particle size of zeolite clay included in high-energy diets for feedlot lambs: Growth performance, dietary energy, carcass traits, and visceral mass.

Objective: Several reports on the effects of zeolite (ZEO) inclusion in diets for feedlot lamb diets have indicated improvements in dietary energy efficiency and decreases in internal fat. Inclusion levels and the type of zeolite used have been the main focus of those reports. However, the possible effect of the zeolite particle size on the growth performance and carcass characteristics has not yet been investigated. Material and Methods: Forty-eight male intact Pelibuey × Katahdin lambs were fed for 67 days with a high-energy diet supplemented with ZEO as follows: 1) basal diet 0% ZEO (control); 2) basal diet 3% ZEO particle size 250 µM (sieve 60); 3) basal diet 3% ZEO particle size 149 µM (sieve 100); and 4) basal diet 3% ZEO particle size 74 µM (sieve 200). ZEO replaced corn grain and soybean meal in equal parts. At the end of feeding, lambs were slaughtered, and variables such as carcass characteristics and visceral mass were evaluated. Results: Particle size did not affect growth performance, carcass characteristics, or visceral mass. The inclusion of ZEO reduced 3.4% of dietary net energy in diets but did not affect dry matter intake or average daily gain, thus improving (p ≤ 0.05) dietary energy efficiency by 2.9%. Except for an 18.9% reduction (p = 0.02) in visceral mass fat, ZEO did not affect other carcass characteristics or visceral organ mass. Conclusion: The particle size studied in the present experiment has not affected any of the variables of growth performance or carcass characteristics. ZEO inclusion could be a strategy to reduce the visceral fat in finishing lambs.

Blend of Essential Oils Supplemented Alone or Combined with Exogenous Amylase Compared with Virginiamycin Supplementation on Finishing Lambs: Performance, Dietary Energetics, Carcass Traits, and Nutrient Digestion.

Two experiments were conducted to compare a supplemental blend of essential oils alone (EO) or combined with enzymes (EO + ENZ) versus virginiamycin (VM), on characteristics of growth performance (Exp. 1) and digestion (Exp. 2) in finishing lambs. Lambs were fed a high-energy finishing diet supplemented with: (1) no supplement (control); (2) 150 mg supplemental EO; (3) 150 mg supplemental EO plus 560 mg alpha-amylase (EO + ENZ); and 4) 25 mg VM. Compared with the control, growth performance response to EO and VM were similar, enhancing (5.7%, p < 0.05) feed efficiency and observed dietary net energy. Compared with control, supplementation with EO + ENZ tended (p = 0.09) to increase dry matter intake (6.8%), improving (p < 0.05) weight gain and feed efficiency (10.4 and 4.4%, respectively). Dietary energy utilization was greater (2.7%, p < 0.05) for EO and VM than EO + ENZ. Treatment effects on the carcass and visceral mass were small, but additive supplementation decreased (p ≤ 0.03) the relative weight of the intestines. There were no treatment effects on measures of digestion nor digestible energy of the diet. Supplemental EO may be an effective alternative to VM in high-energy finishing diets for feedlot lambs. Combination EO + ENZ may further enhance dry matter intake, promoting increased weight gain.

Evaluation of two in-house immunoenzymatic tests to serodiagnose subclinical paratuberculisis in a sheep flock in Mexicali valley, Mexico.

Paratuberculosis (PTB) or Johne's disease is a common ruminant infectious disease caused by Mycobacterium avium subsp. paratuberculosis (MAP). In this study, two MAP antigens were compared for their diagnostic utility to detect subclinical PTB in a sheep flock in Mexicali, Mexico. Sheep (n = 31) without clinical signs but positive on a direct fecal-polymerase chain reaction were tested with two preabsorbed in-house enzyme linked immunosorbent assays (ELISAs) using: (1) an ethanol-extracted surface lipid antigen (EVELISA) and (2) a protoplasmic antigen (ELISA-PPA). Sensitivities of the EVELISA and ELISA-PPA were 84% (95% CI; 66-95%) and 29% (95% CI; 14-48%), respectively. The EVELISA test could be a fast and effective way to identify subclinical ovine PTB for severely affected flocks.