Zilpaterol Hydrochloride Research Articles

Effects of zilpaterol hydrochloride and soybean oil supplementation on feedlot performance and carcass characteristics of hair-breed ram lambs under heat stress conditions

Forty Dorper × Pelibuey ram lambs initially weighing 31.7 ± 2.30 kg were stratified by BW and randomly assigned to treatments under a completely randomized design with a 2 × 2 factorial arrangement of treatments to evaluate effects of zilpaterol hydrochloride (ZH; 0 or 10 mg/lamb daily) and soybean oil (SBO; 0 or 6%) on feedlot performance, carcass characteristics, and wholesale cut yield of ram lambs under heat stress conditions. After a 34-d feeding period, all lambs were harvested. Climatic conditions were of moderate heat stress (average temperature 35.7°C) for lambs during the study. Interactions ZH × SBO were not observed (P ≥ 0.11) for any of the variables evaluated. During the first 17 d of experiment, ZH increased (P ≤ 0.05) BW, ADG, and G:F without affecting feed intake (P = 0.40), but from d 18 to 34 and the entire 34-d feeding period, feedlot performance was not affected (P = 0.18) by ZH. Also, ZH decreased KPH, dressing percent, LM area, LM pH at 24 h postmortem, and leg perimeter (P ≤ 0.04). Renal fat (P = 0.03) decreased with ZH while other noncarcass components were not affected (P ≥ 0.06) by ZH supplementation. Leg yield (P = 0.01) and plain loin (P = 0.04) decreased with ZH and yields of other wholesale cuts were not affected (P ≥ 0.10) by ZH. Feedlot performance (P ≥ 0.20) and wholesale cut yield (P ≥ 0.21) were not affected by SBO. Additionally, dressing percentage decreased (P < 0.01) with SBO while other carcass characteristics (P ≥ 0.12) were not affected by SBO. In conclusion, inclusion of both ZH and SBO in feedlot finishing diets did not improve feedlot performance, carcass characteristics, or wholesale cut yield of hair-breed ram lambs under moderate heat stress. Feedlot performance responded only to ZH and only during the first 17 d of the feeding period. In addition, some carcass characteristics of economic importance, such as dressing, LM area, and leg yield, were improved by ZH.

Comparative effects of zilpaterol hydrochloride and ractopamine hydrochloride on growth performance, carcass characteristics, and longissimus tenderness of feedlot steers fed barley-based diets

Comparative effects of zilpaterol hydrochloride and ractopamine hydrochloride on growth performance, carcass characteristics, and longissimus tenderness of feedlot steers fed barley-based diets

Effects of dietary ractopamine hydrochloride and zilpaterol hydrochloride supplementation on performance, carcass traits, and carcass cutability in beef steers1

British × Continental steers (initial BW = 484.6 kg) were fed at a commercial feed yard to evaluate the effects of β-agonists on live performance, carcass characteristics, and carcass subprimal yield. Weights and ultrasonic measurements were used to allocate steers to pens (n = 40) divided equally into 4 blocks, with 2 treatment replicates per block. Pens were randomly assigned to 1 of 5 treatments: control; ractopamine-HCl (RH) fed at 200 or 300 mg • steer(-1) • d(-1), or 400 mg • steer(-1) • d(-1) top dress for the final 30 d of feeding; or zilpaterol-HCl (ZH) fed at 7.5 mg/kg beginning 23 d before slaughter with a 3-d withdrawal period. Steers were harvested by block at a commercial facility over 4 wk. Carcass based performance measures were calculated using initial pen weights and actual DMI. From each pen, eight carcasses that were within ± 13.6 kg of the mean pen HCW were selected such that two carcasses were within each of the following four Yield Grade (YG) ranges: YG ≤ 2.8; 2.9-3.2; 3.3-3.5; YG > 3.5. Carcasses were fabricated by plant personnel to determine subprimal yield. Steers fed ZH had higher carcass-based ADG and carcass-based G:F compared with all other treatments (P < 0.05). Carcass-based ADG and carcass-based G:F were higher in RH treatments compared with controls (P < 0.05). Steers fed ZH had higher dressing percentages (1.0 to 1.6%) and larger LM area (4.3 to 6.7 cm(2)) than all other treatments (P < 0.05). Use of RH 400 and ZH increased HCW 6.3 and 11.1 kg, respectively compared with controls (P < 0.05). Compared with controls, RH 300 and ZH decreased marbling score and the frequency of carcasses qualifying for upper 2/3 Choice premiums (P < 0.05). Beta-agonists increased subprimal yield from the round and loin; however, blade meat was the only cut from the rib or chuck affected by β-agonists. Results from this study indicated improvements in performance and carcass traits as a result of β-agonist use; however, differences between ZH, RH 400, and RH 300 treatments were minimal for carcass traits and cutability. Increases in saleable yield following β-agonist use were not uniformly distributed across the four major primals and the majority of weight gain occurred in the lower priced cuts of the round and chuck. Increased response of the lower priced cuts to β-agonists could have economic implications to packers.

Effects of β-agonist zilpaterol hydrochloride feeding and supplementation period on growth and carcass characteristics of Lori-Bakhtiari lambs

Fifty six Lori-Bakhtiari feedlot lambs (initial BW=44±4.7kg) were used in a 2×3+1 factorial experimental design to evaluate the effects of 3 feeding regimens of zilpaterol hydrochloride (ZH) for the last 28 and 42dbefore slaughter on growth performance, carcass characteristics and some plasma metabolites. The continuous feeding of ZH (daily regimen), intermittent 1d feeding ZH followed by 1d of withdrawal (1 on 1 off regimen), and intermittent 2d feeding ZH followed by 2d of withdrawal (2 on 2 off regimen) were employed as the different regimens. The lambs were assigned to one of seven treatments (8 lambs/treatment) based on initial BW. Lambs were fed a diet formulated to contain 14% CP and 2.45Mcal/kgDM of metabolizable energy (ME) supplemented with 0.2mg ZH/kg of live weight d−1. The basal diet without ZH was the added control group. Lambs fed ZH continuously for 28d had higher (P<0.001) feed efficiency compared to the control group and other intermittent regimens. Neither feeding regimen nor period had any significant effect (P>0.05) on final BW, total weight gain, average daily gain and dry mater intake. Hot and cold carcass weights and dressing percentage were greater for daily feeding for either 28 or 42d and for the 1 on 1 off-42d treatments than for the control and the other groups fed ZH (P<0.05). Longissimus dorsi muscle area was increased (P<0.01) by daily-28d compared to the control. Back fat thickness tended to be lower (P=0.063) in pooled ZH-treated groups whereas there was no effect of ZH on the proportion of final weight of the fat-tail. Daily-28d and 1 on 1 off-42d groups had lower intramuscular fat content (P<0.01) than the control group. Plasma concentrations of urea were decreased (P<0.05) in daily-28/42d groups compared to the control. Also, there were lower concentrations of urea after 42d of ZH feeding compared to 28d of ZH feeding (P<0. 05). Overall, feeding ZH in daily for either 28 or 42d before slaughter as well as for 42d on alternate days improved feed efficiency ratio and some carcass characteristics. While backfat tended to be decreased by ZH there was no effect on fat-tail in Lori-Bakhtiari lambs.

Effect of zilpaterol hydrochloride on growth performance and carcass characteristics of wether goats

Zilpaterol hydrochloride (ZH) supplementation was evaluated on performance of growing goats for the last 42 days before slaughter. Forty-eight Anglo-Nubian×Criollo animals (12 per treatment) were randomly assigned to one of four treatments (ZH at daily doses of 0.0, 0.1, 0.2 or 0.3mg/kg of BW in diet) in a complete block design. Basal diet contained 16.3% CP and 2.5 Mcal/kg ME. The ZH supplementation at doses of 0.1, 0.2 and 0.3mg/kg of BW increased ADG by 22.1, 54.0 and 56.6%, and gain/feed ratio by 20.0, 40.0 and 60.0%, respectively. The DMI (g/kg of BW0.75) increased quadratically (P=0.037). Carcass weight and dressing percentage (DP) augmented linearly (P≤0.031) as level of ZH increased in diet. The ZH supplementation increased (P≤0.023) longissimus muscle area (LM) and leg perimeter (LP) with a linear improvement (P<0.001) of LM area by 12.2% and 21.0% as ZH level increased in diet. The neck perimeter (NP) observed a quadratic trend (P<0.035) with greater values at 0.1 and 0.2mg/kg of ZH. For each increment of 0.1mg/kg in the ZH level, the percentage of fat in kidney, heart and pelvis tended to decrease by 4% (P=0.089). Other carcass characteristics were not significantly affected (P≥0.311) by ZH administration, but tended to reduce (P≤0.094) redness (a*) and chroma (C*) values in the longissimus muscle. It was observed a linear tendency to diminish pH (P=0.072). However, no differences (P>0.05) or trends (P>0.10) were detected on purge loss (PL) or cooking loss (CKL). Growth differences between wether goats fed ZH doses of 0.2 or 0.3mg/kg of BW were small, and therefore lower dose of 0.2mg/kg of BW seems enough to enhance growth. Moreover, the carcass characteristics showed minor differences between levels of ZH supplementation, and therefore could be considered that the lower dose of 0.1mg/kg of BW of ZH was sufficient to improve these traits. It is concluded that addition of ZH to diets of wether goats increased growth performance and carcass characteristics in a similar manner to that reported for cattle and sheep.

Effects of ractopamine hydrochloride and zilpaterol hydrochloride supplementation on longissimus muscle shear force and sensory attributes of calf-fed Holstein steers1

The effect of ractopamine hydrochloride (RH) and zilpaterol hydrochloride (ZH) on slice shear force (SSF) and sensory characteristics of beef from calf-fed Holstein steers was evaluated. All steers were implanted with a progesterone (100 mg) plus estradiol benzoate (10 mg) implant followed by a terminal trenbolone acetate (200 mg) plus estradiol (40 mg) implant. Steers were blocked by weight into pens (n = 32) randomly assigned to 1 of 4 treatments: control, RH fed at 300 mg·steer(-1)·d(-1) (RH 300) or RH fed at 400 mg·steer(-1)·d(-1)(RH 400) for the final 31 d of finishing, or ZH fed at 6.8 g/t for 21 d with a 5-d withdrawal before harvest. Fourteen carcasses were randomly selected from each pen, and two LM samples (1 per side) were excised and aged either 14 or 21 d before SSF testing. For trained panel evaluation, two steaks were collected from each of 60 low Choice strip loins (20 each from control, RH 300, and ZH treatments) and aged either 14 or 21 d. Steers fed RH and ZH produced steaks with SSF values that were 9% to 25% higher than controls. No difference in SSF was detected between the two levels of RH (P > 0.05). Compared to controls, the probability of steaks aged 14 d failing to meet SSF requirements to be certified tender (SSF < 20 kg) was increased 0.15, 0.17, and 0.26 in steers fed RH 300, RH 400, and ZH, respectively. Compared to controls, the probability of steaks aged 21 d having SSF values >20 kg was increased 0.03, 0.08, and 0.16 in steers fed RH 300, RH 400, and ZH, respectively. Steaks from Select carcasses of steers fed ZH aged 21 d postmortem had double the probability (0.39 vs. 0.17) of having SSF values >20 kg compared to steaks from steers fed either level of RH (P < 0.05). This difference tended to be identical in steaks from Select carcasses 14 d postmortem (0.50 vs. 0.33; P = 0.11); however, no difference was found in low Choice samples at 14 or 21 d postmortem. Trained panelists rated steaks aged 14 d from steers fed ZH lower for overall tenderness and flavor compared to controls (P < 0.05); however, no difference was found between controls and those fed RH 300. Steaks from steers fed ZH aged 21 d were rated lower for overall tenderness and juiciness compared to controls and those from steers fed RH 300 (P < 0.05). This study suggests RH and ZH negatively impact sensory attributes of beef from calf-fed Holstein steers.

Agonistas beta-adrenérgicos como aditivo para bovinos de corte

Os receptores de agonistas beta-adrenérgicos (β-AA) estão presentes em praticamente todos os tipos de células de mamíferos e são estimulados pelas catecolaminas (adrenalina e noradrenalina) produzidas pelo próprio organismo. Os agonistas β-AA são substâncias sintéticas com estrutura similar a estas aminas. Quando fornecidos na ração alteram a composição corporal dos animais, afetando a repartição dos nutrientes em favor da deposição proteica e diminuindo a lipogênese. Apesar dos mecanismos de ação não serem completamente entendidos, estes podem causar alterações morfofisiológicas, tais como o aumento do fluxo sanguíneo, a diminuição do nível plasmático de insulina, a diminuição da lipogênese e a hipertrofia muscular principalmente nas fibras do tipo II. Observam-se também alterações na motilidade do trato gastrointestinal e secreções, além da influência direta sobre as bactérias do rúmen, podendo alterar a digestibilidade da dieta. Os agonistas β-AA liberados em alguns países para utilização em bovinos de corte são o Cloridrato de Ractopamina e o Cloridrato de Zilpaterol. De acordo com dados de literatura, a inclusão destes aditivos na dieta de bovinos confinados tem sido relacionada com aumento na eficiência alimentar e ganho de peso diário, e igual ou menor consumo de ração. Nas características de carcaça tem sido observado aumento no peso das carcaças, e aumento da área de olho de lombo, porém com possibilidade de diminuição da espessura de gordura subcutânea e de marmoreio. Avaliações em painel sensorial da carne de animais consumindo agonistas β-AA mostraram diminuição na maciez, com igual ou menor suculência. Os agonistas β-AA melhoram o desempenho e as características de carcaça, porém mais estudos são necessários para comprovar se possuem influência negativa nas características organolépticas da carne.

The effect of supplementing zilpaterol hydrochloride on feeding performance and carcass characteristics of steers sorted by leptin genotype

The focus of this investigation was to identify interactions that may exist among alleles of the leptin gene and supplementation of zilpaterol hydrochloride (ZH). Steers (n = 4,246; initial BW = 389.8 ± 8.8 kg) were genotyped and sorted into 1 of 3 leptin genotype (LG) groups (homozygous normal [CC], heterozygous [CT], or homozygous mutant ) from a candidate pool of 7,506 steers. Steers were allocated into 48 pens of which one-half were fed the β-adrenergic agonist ZH and the balance, a control diet. During the pretreatment period (d 1 to 102), cattle of the TT genotype exhibited increased (P = 0.02) DMI compared to other genotypes and lower G:F than the CC genotype (P = 0.03). Cattle of the CT genotype had lower (P = 0.02) ADG compared to other genotypes for the treatment period. Cattle fed ZH had improved (P < 0.01) ADG and G:F compared to cattle on the control diet for both the treatment and entire study periods (d 1 to 125). For the entire study period, cattle of the TT genotype had greater (P = 0.03) DMI than the CT allele, with CT cattle having the lowest (P < 0.01) ADG and CC cattle having greatest (P < 0.01) G:F of all alleles. Cattle of the TT genotype had greater (P = 0.03) final shrunk weight than the CT allele. Cattle of the TT genotype had lower (P = 0.04) dressed yield compared to CT cattle and greater (P = 0.01) marbling score compared to CC cattle, with a concurrent increase (P < 0.01) in calculated empty body fat (EBF) over all alleles. Cattle fed ZH had greater (P < 0.01) final shrunk weight, HCW, dressed yield, and LM area coupled with reduced (P < 0.01) marbling score, s.c. fat depth, EBF, and calculated USDA yield grade compared to control steers. Carcasses of the TT allele had a greater (P = 0.01) proportion of Choice carcasses than CT or CC alleles and lesser (P = 0.03) proportion of Select carcasses than CC alleles. Additionally, ZH supplemented cattle had fewer (P < 0.01) carcasses grading Premium Choice or better, Choice, and yield grade 3, 4, and 5 with subsequently more (P < 0.01) carcasses grading Select, Standard, and yield grade 1. Differences in live and carcass performance exist among leptin alleles, which may allow for sorting and improved timeliness of fed beef marketing.

Effects of ractopamine hydrochloride and zilpaterol hydrochloride supplementation on carcass cutability of calf-fed Holstein steers1

Effects of ractopamine hydrochloride (RH) and zilpaterol hydrochloride (ZH) on saleable yield of carcass sides from calf-fed Holstein steers were evaluated using steers implanted with a progesterone (100 mg) plus estradiol benzoate (10 mg) implant followed by a terminal trenbolone acetate (200 mg) plus estradiol (40 mg) implant. Steers were blocked by weight into pens (n = 32) randomly assigned to one of four treatments: control, RH fed at 300 mg•steer(-1)/d(-1) (RH 300) or RH fed at 400 mg•steer(-1)/d(-1) (RH 400) the final 31 d of finishing, and ZH fed at 60 to 90 mg•steer(-1)/d(-1) (7.56 g/ton on a 100% DM basis) for 21 d with a 5 d withdrawal before harvest. Eight to nine carcass sides were randomly selected from each pen; carcass sides with excessive hide pulls, fat pulls or bruises were avoided. Cutout data were collected within a commercial facility using plant personnel to fabricate sides at a rate of one every 3 to 4 min into items typically merchandised by the facility. All lean, fat and bone were weighed and summed back to total chilled side weight with a sensitivity of ± 2% to be included in the data set. Compared to controls, β-agonists increased saleable yield of whole-muscle cuts by 0.61%, 0.86% and 1.95% for RH 300, RH 400 and ZH, respectively (P < 0.05). Percent fat was less in carcasses from the ZH treatment compared to controls (P < 0.05); however, this difference was not observed between RH treatments and controls (P > 0.05). Percent bone was less in the ZH treatment due to increased muscle (P < 0.05). The percent of chilled side weight comprised of trimmings was unchanged between treatments, but on a 100% lean basis, RH 400 and ZH increased trim yields (P < 0.05). Analysis of saleable yield by primal showed a fundamental shift in growth and development. Beta-agonists caused a shift in proportion of saleable yield within individual primals, with a greater portion produced from the hindquarter relative to the forequarter, specifically in those muscles of the round (P < 0.05). Beta-agonists increased saleable yield, but these effects were not constant between all major primals. The cutout value gained by packers as a result of β-agonist use may be influenced more by reduced fatness and increased absolute weight if musculature is primarily increased in the lower priced cuts of the carcass.

Treatment and resolution of zilpaterol hydrochloride toxicity in aQuarterHorse gelding

SummaryZilpaterol hydrochloride is a β‐2 agonist utilised as a repartitioning agent in cattle. In recent years, it has also been used illicitly among human athletes and body builders, and administered to racehorses. While there are numerous anecdotal reports of the effects of zilpaterol in horses, this is the first documented clinical case of equine zilpaterol toxicity. The horse presented with marked tachycardia, profuse sweating and generalised muscle fasciculations. Ultimately, treatment was initiated with propranolol and the horse made a complete recovery.

Effects of ractopamine hydrochloride and zilpaterol hydrochloride supplementation on longissimus muscle shear force and sensory attributes of beef steers 1

Effect of ractopamine hydrochloride (RH) and zilpaterol hydrochloride (ZH) on LM shear force and sensory attributes was determined using pens (n = 40) British × Continental crossbred steers randomly allocated to one of the following treatments: control; RH fed at 200 (RH 200) or 300 mg • steer(-1) • d(-1) (RH 300), or 400 mg • steer(-1) • d(-1) (RH 400) top-dressed for the final 30 d of feeding; or ZH fed at 7.5 mg/kg, beginning 23 d before slaughter with a 3-d withdrawal. Two replicates (pens) per treatment were represented in four blocks. Eighteen carcasses per pen were randomly selected and one 5-cm LM sample was removed from both carcass sides to be used for shear force and sensory evaluation. Samples were aged for 14 d, frozen at -28.8 °C, and cut into 2.5-cm steaks. All steaks were cooked to an internal temperature of 71.1 °C before being evaluated for Warner-Bratzler shear force (WBSF), slice shear force (SSF), or being fed to trained sensory panelists. Increasing dose and potency of β-agonist increased WBSF by 4 to 17% and SSF by 5 to 24% (P < 0.05). Steaks from steers fed ZH had higher WBSF and SSF values compared with all other treatments (P < 0.05), whereas steaks from controls and steers fed RH 200 were not different (P > 0.05). Probability of steaks failing to meet shear force standards to be certified tender (WBSF <4.4 kg, SSF < 20 kg) was increased from an initial probability of <0.06 in steaks from steers in the control treatment to 0.10 to 0.20 in steers fed RH 400 or ZH (P < 0.05). No difference was detected in panel ratings for overall tenderness of steaks from steers fed RH 200 compared with controls (P > 0.05). Steaks from steers fed RH 300 and RH 400 were comparable for all sensory attributes; however, both RH 300 and RH 400 were rated lower for overall tenderness than controls (P < 0.05). Panelists failed to detect differences in overall tenderness of steaks from steers fed RH 400 and ZH (P < 0.05). Panelists detected no difference in flavor profile or juiciness among treatments (P > 0.05). Results from this study indicated β-agonists negatively affected beef tenderness and these effects may be more noticeable in steers supplemented with ZH and higher doses of RH.

MEAT SCIENCE AND MUSCLE BIOLOGY SYMPOSIUM—Implant and beta agonist impacts on beef palatability1

The use of anabolic implants has a long-standing place in the cattle feeding industry, due to their positive impact on growth performance and subsequent profitability. However, implants can have adverse effects on carcass quality, shear force, and eating quality depending on the dose and frequency, or what some refer to as the aggressiveness of the implant regimen administered. Within the past decade, a new class of growth promotants, known as β-adrenergic agonists (βAA), has emerged in the beef feeding industry in the United States. Currently, 2 have gained U.S. Food and Drug Administration approval for use in beef finishing diets to improve performance and carcass yields. Much like anabolic implants, these repartitioning agents can have negative effects on Warner-Bratzler shear force (WBSF), but the differences do not necessarily translate directly to consumer responses for palatability and acceptance in some instances, especially when tenderness is managed through proper postmortem aging. As researchers continued to investigate the mechanisms responsible for the impact of βAA, inevitably this led to consideration of the interaction between βAA and anabolic implants. Early work combining zilpaterol hydrochloride (ZH) with anabolic implants improved performance, carcass yield, and meat yield with additive negative effects on WBSF. Similar results were produced when pairing ZH with anabolic steroids equipped with various release patterns. As with any tool, the key to success is proper management. Certain cattle populations may be better suited to receive growth promotants such as implants and βAA, and postmortem management of subprimal cuts becomes vital when producers take more aggressive approaches to improve performance and yield. The objective of this review is to overview research findings related to the impact of growth promotant technologies on beef palatability, focusing specifically on the role of implants and βAA on carcass quality, beef tenderness, and consumer responses for meat palatability.

Growth promoting technologies reduce greenhouse gas, alcohol, and ammonia emissions from feedlot cattle

Increased animal productivity has the potential to reduce the environmental impact per unit of consumable product and is believed to be the most promising and sustainable mitigation technique to meet increasing demand for high quality protein. The feedlot industry uses ionophores, antibiotics, growth implants, and β2-adrenergic agonists to improve health and growth performance of cattle. These technologies not only increase productivity but also alter microbes in the rumen and increase nitrogen retention in the animal, which may lead to changes in greenhouse gas (GHG), volatile organic compound (VOC), and ammonia (NH3) emissions from feedlot cattle. The present study investigated GHG, VOC, and NH3 emissions from 160 Angus crossbred steers. Steers were blocked by weight in a randomized block design and assigned to 16 pens of 10 animals each. Treatments applied were 1) control (CON; no technology application), 2) monensin and tylosin phosphate (MON), 3) monensin, tylosin phosphate, and growth implant (IMP), and 4) monensin, tylosin phosphate, growth implant, and zilpaterol hydrochloride (fed during the last 20 d of the feeding period; BAA). Cattle were on feed for an average of 107 d. Performance variables (DMI, BW, ADG, and G:F) and carcass traits (HCW, dressing percent, KPH, LM area, fat thickness, marbling score, yield grade, and quality grade) were measured. Gaseous emissions were measured during the last 10 d of the feeding period when animals were housed in 4 totally enclosed identical cattle pen enclosures. To quantify gaseous emissions a 4×4 Latin square design (n=4) was used. Gaseous emissions were analyzed using Proc Mixed in SAS and reported in grams per kilogram HCW per day and grams per kilogram per animal per hour. Treatment with IMP and BAA increased (P<0.05) ADG, final BW, and HCW. Cattle on BAA had greater HCW and LM area (P<0.05) and had lower (P<0.05) CH4, methanol, and NH3 emissions per kilogram HCW than cattle on the remaining treatments. Methane emissions were similar for CON and IMP treated cattle. Nitrous oxide emissions were similar across CON, MON, and IMP treated cattle and were higher in BAA treated cattle (P<0.05). The present study provides a better understanding of how application of growth promoting technologies to feedlot steers affects GHG, VOC, and NH3 emissions per kilogram of product.

Effects of supplemental lysine and methionine in combination with zilpaterol hydrochloride on muscle fiber type and size in finishing feedlot cattle

Effects of supplemental lysine and methionine in combination with zilpaterol hydrochloride on muscle fiber type and size in finishing feedlot cattle

Effects of supplemental lysine and methionine in combination with zilpaterol hydrochloride on beta-adrenergic receptors in finishing feedlot cattle

Effects of supplemental lysine and methionine in combination with zilpaterol hydrochloride on beta-adrenergic receptors in finishing feedlot cattle

Warner-Bratzler shear force assessment of serially-harvested calf-fed Holstein steers fed zilpaterol hydrochloride

Warner-Bratzler shear force assessment of serially-harvested calf-fed Holstein steers fed zilpaterol hydrochloride

Changes in total and heat soluble collagen located in the longissimus lumborum, gluteus medius, and psoas major in implanted cattle fed zilpaterol hydrochloride

Changes in total and heat soluble collagen located in the longissimus lumborum, gluteus medius, and psoas major in implanted cattle fed zilpaterol hydrochloride

Administration of zilpaterol hydrochloride alters feedlot performance, carcass characteristics, muscle, and fat profiling in finishing Hanwoo steers

Forty Hanwoo steers weighing 759.3±50.3kg were used to evaluate the effects of treatment with zilpaterol hydrochloride (ZH) in terms of feedlot performance, carcass characteristics, and fatty acid composition. We hypothesized that treatment of ZH increases meat amount in long-fed Hanwoo steers. Animals were blocked by BW, and assigned to one of two treatments within each block. Five animals were housed and fed in each of 8 pens. All animals were weighed before and after ZH treatment. Total BW gain over the 23-d period was adjusted to d 0 by covariant analysis. Steers receiving ZH (1.6g/h/d) exhibited significantly increased weight gain (P<0.05) over CON steers. Performance analysis showed that ZH had significant effects on total weight gained average daily gain (ADG). There were also treatment effects (P<0.05) on dressing percentage, LM area, and yield grade. The total percentage of lean muscle was increased by the administration of ZH, and the percentage of fat was decreased by ZH treatment (P<0.05). The weights of tenderloin, striploin, chuck, round, shank, and brisket were significantly increased by ZH treatment compared to CON steers (P<0.05). Analyses of the physico-chemical characteristics of the longissimus muscle indicated that shear force, purge loss, and cooking loss were increased with ZH treatment (P<0.05). However, there were no treatment effects on marbling score and fatty acid compositions (P>0.05). We conclude that the administration of ZH increased LM area and primal yield grades, but had no change in the fatty acid profile.

Effects of zilpaterol hydrochloride and soybean oil supplementation on physicochemical and sensory characteristics of meat from hair lambs

Forty Dorper×Pelibuey male lambs were used to obtain the Longissimus dorsi muscle to evaluate the effect of zilpaterol hydrochloride (ZH) and soybean oil (SO) on chemical (moisture and intramuscular fat), physicochemical quality (pH, water holding capacity [WHC], Warner Bratzler shear force [WBSF], color) and sensory attributes of meat. Lambs were individually housed in pens and assigned randomly to 1 of 4 treatments (n=10): (1) control (no ZH or SO); (2) supplemented with ZH (10mg/animal daily); (3) addition of 6% SO, and (4) supplemented with ZH (10mg/animal daily)+addition of 6% SO. Feeding ZH decreased color parameters and intramuscular fat (P<0.05), and increased pH and WBSF. Panelists observed a decreased in overall color, harder meat and higher content of connective tissue (P<0.05) by ZH supplementation. Feeding SO increased (P<0.05) a* value and WHC, without modifying the sensory characteristics.

Impact of a leptin single nucleotide polymorphism and zilpaterol hydrochloride on growth and carcass characteristics in finishing steers

A total of 4,178 steers (mean initial BW = 403.9 ± 16.04 kg) were used to test the interactive effects, if any, of leptin R25C genotypes (CC, CT, or TT) and zilpaterol hydrochloride (ZH) feeding duration on growth performance and carcass traits. Steers were blocked by arrival at the feed yard, genotyped for the leptin SNP, allotted to genotype-specific pens (90 steers/pen), and assigned randomly within genotype and block to 0 or 21 d of dietary ZH. All pens within a block were slaughtered on the same day (132.1 ± 10.9 d on feed). Final BW of steers fed ZH was 6.0 kg heavier (P = 0.008), and ZH-fed steers had greater (P = 0.003) ADG than steers not fed ZH. Feeding ZH decreased DMI in steers with increased frequency of the T allele (9.67, 9.53, and 9.28 kg/d for CC, CT, and TT, respectively), but DMI increased with the frequency of the T allele (9.68, 9.90, and 10.1 kg for CC, CT, and TT, respectively) when ZH was not fed (leptin genotype × ZH, P = 0.011). At the conclusion of the study, ultrasonic fat was greatest for TT steers (11.4 ± 0.28 mm) and least (P = 0.003) for CC steers (11.0 ± 0.25 mm). Regardless of ZH-feeding duration, TT steers produced a greater (P = 0.006) percentage of USDA yield grade (YG) 4 or higher carcasses (5.4 vs. 2.7%) and a lesser (P = 0.006) percentage of YG 1 carcasses (17.7 vs. 26.8%) than CC steers. In addition, ZH-fed steers produced a greater (P < 0.001) percentage of USDA YG 1 carcasses (25.9 vs. 16.2%) and a lesser (P < 0.001) percentage of YG 4 or higher carcasses (1.6 vs. 6.0%) than steers fed the control diet. Marbling scores and the percentage of carcasses grading USDA Choice and Prime were greater in TT than CC steers when fed diets devoid of ZH, but both marbling and quality grades did not differ among leptin genotypes when fed ZH for 21 d (leptin genotype × ZH, P ≤ 0.03). The amount of HCW gain tended to be less (P = 0.095) for steers of the TT genotype (12.7 kg) than either CC (16.3 kg) or CT (17.0 kg) genotypes. Results indicated that leptin R25C genotype impacted most traits associated with fatness whereas feeding ZH for 21 d affected HCW and ADG positively but impacted feed intake, marbling, and USDA quality grades negatively.