Effects of immunocastration and a β-adrenergic agonist on retail cuts of feedlot finished Nellore cattle

Administering an Appeasing Substance to Improve Performance, Neuroendocrine Stress Response, and Health of Ruminants

Simple Summary

Stress is present in several management activities of beef and dairy cattle, leading to health and productive losses to the herd. Therefore, strategies are warranted to reduce any losses related to these stressful situations, and bovine appeasing substance (BAS) is arising as a potential technology in livestock production settings. Several peer-reviewed publications have evaluated BAS in different production settings, such as weaning, feedlot entry, castration, transport to the slaughterhouse, and pre-weaning dairy cattle. Altogether, performance, health, and carcass traits have been positively impacted by BAS administration, demonstrating the efficacy of this technology for ruminants.

Abstract

The present review demonstrates the main attributes of stress-related responses in ruminants, and the potential interaction with the immune system of the host is also presented, demonstrating that alternatives that reduce the response to stressful situations are warranted to maintain adequate health and performance of the herd. In this scenario, pheromones and their modes of action are presented, opening space to a recent technology being used for ruminants: bovine appeasing substance (BAS). This substance has been used in different species, such as swine, with positive behavioral, health, and performance results. So, its utilization in ruminants has been reported to improve performance and inflammatory-mediated responses, promoting the productivity and welfare of the livestock industry.

Effects of the Duration of Zilpaterol Hydrochloride Supplementation and Days on Feed on Performance, Carcass Traits and Saleable Meat Yield of Nellore Bulls

Simple Summary

Zilpaterol hydrochloride (ZH) is a β-adrenergic agonist (βAA) to be feed to feedlot cattle at a rate of 8.3 mg/kg during the final 20 to 40 d of the finishing period followed by a minimum 3 d withdrawal period. This compound has the potential to increase animal performance, improve carcass weight and meat yield. Although significant information regarding the effects of duration of ZH supplementation and days on the feed of Bos taurus cattle has been provided, there is a lack of information relative to its effects on Bos indicus breeds such as Nellore cattle. The current study aimed to evaluate the effects of the duration of ZH supplementation and DOF on performance, carcass characteristics, and saleable meat yield of Nellore bulls. The HCW and total saleable meat yield linearly increased with the duration of ZH supplementation as well as when the length of the feedlot period increased. We recommend supplementing ZH for Nellore bulls at least for 20 days, independently of days on feed, to improve hot carcass weight, hindquarter, and saleable meat yields of Nellore bulls.

Abstract

This study evaluated the effects of the duration of ZH supplementation and days on feed (DOF) on performance, carcass characteristics, and saleable meat yield of Nellore young bulls. The fixed effects included the duration (0, 20, 30, or 40 d before slaughter plus a 3 d ZH withdrawal period—8.33 mg of ZH/kg of DM) and DOF (90 and 117 d). Feed efficiency (G:F) linearly increased when the duration of ZH supplementation increased (p < 0.01). Nellore bulls fed ZH had greater HCW (p < 0.01), dressing percentage (p < 0.01) and Longissimus muscle area (LMA) (p < 0.01), but less 12th-rib fat (p = 0.04) than the control group. The hot carcass weight (HCW) (p < 0.01), and dressing percentage increased linearly (p < 0.01) with the increase of duration of ZH supplementation. The HCW, ossification, and 12th-rib fat increased with DOF (p < 0.01). The ZH supplemented group had most of the individual cuts of hindquarters and total saleable meat increased compared with the control. Zilpaterol hydrochloride was effective in improving hot carcass weight, hindquarter, and saleable meat yields of Nellore bulls when fed for at least 20 d before slaughter, independently of days on feed.

Welfare traits of Bos indicus cattle castrated immunologically and fed beta-adrenergic agonists

Objective

This work was carried out to evaluate the effects of zilpaterol hydrochloride (ZH) and ractopamine hydrochloride (RH) combined with immunocastration on the welfare traits of feedlot Nellore cattle.

Methods

Ninety-six Nellore males (average body weight [BW] = 409±50 kg; average 20 mo of age) were divided into two groups according to BW; half of the animals in each group received two doses of an immunocastration (ImC) vaccine in a 30 day interval, and the other half did not receive the vaccine (NoC). Afterward, the animals were housed and fed a common diet for 70 days. Then, they were split into three groups and fed one of the following diets for 30 additional days: control (CO) diet, with no β-AA; ZH diet, containing 80 mg/d ZH; and RH diet, containing 300 mg/d RH. Welfare traits were assessed by monitoring body surface temperature using infrared thermography (IRT) and plasma cortisol and temperament measurements.

Results

There was no interaction between sexual condition and diet for any trait. The ImC and NoC groups did not differ in rectal and ocular temperatures. The ImC animals had higher flight speeds (p = 0.022) and tended to have higher cortisol levels (p = 0.059) than the NoC animals. Animals fed ZH and RH did not differ in cortisol levels, respiratory rate, rectal temperature, temperature measured by IRT, or temperament behaviour.

Conclusion

The ImC animals showed a less stable temperament during handling practices than NoC, whereas ZH and RH supplementation had no adverse effects on animal welfare.

Silva S, Netto AS. Castration age and growth, meat production and meat quality of Nellore male cattle

Castration in beef cattle production has been proposed to reduce sexual and aggressive behaviour, increase carcass fat deposition, and improve meat quality traits, such as tenderness and juiciness. The aim of the present study was to evaluate the effects of the age of castration on performance, subprimal yield and meat quality of Nellore cattle raised on a pasture system. A total of 24 Nellore males were raised in a grass-fed system with Brachiaria brizantha since birth until slaughter (at 30 months old). Three treatments were assigned: castration at weaning (CW); castration at 20 months old (C20); and intact bulls (NoC). Males were weighed, and muscle and fat thickness were periodically evaluated by ultrasonography. The cold carcass weight, dressing and carcass pH (pH 24), and subprimal cut weights were recorded after 24 h of chilling. Samples of Longissimus lumborum (LL) were taken to measure meat quality traits. Animals that were castrated at weaning had lower bodyweight after 10 months of age with no changes in the supplement intakes, average daily gain, hot carcass weight and cold carcass weight compared with NoC. Intact males had greater cooking losses and carcass yield compared with others, with no differences for LL pH 24 according to the treatments. The castration did not change the LL muscle area, but decreased total forequarter, chunk, shoulder and eye of round weights, and increased the back fat over LL and rump fat. Animals castrated at weaning had higher marbling compared with others. In addition, regardless of age, castration improved tenderness, increased LL total lipids and decreased moisture compared with NoC. For sensory property, steers castrated at 20 months of age had lower juiciness, and NoC had a greater global sensory property compared with steers castrated at 20 months old. In conclusion, steers castrated at weaning had lower growth rate, final bodyweight and meat production compared with intact males. However, when castration was performed at 20 months, animals did not differ in most cases from castration at weaning and NoC. Tenderness was improved by castration, but sensory traits did not differ between groups.