Mineral composition of serially slaughtered Holstein steers supplemented with zilpaterol hydrochloride.

Calf-fed Holstein steers (n = 115; 449 ± 20 kg) were utilized in a serial harvest experiment. A baseline group of five steers was harvested after 226 d on feed (DOF), which was designated day 0. The remaining cattle were assigned randomly to 11 harvest groups, with slaughter every 28 d. Cattle were either not (CON) or were fed zilpaterol hydrochloride for 20 d followed by a 3 d withdrawal (ZH). There were five steers per treatment in each slaughter group ranging from days 28 to 308. Whole carcasses were divided into lean, bone, internal cavity, hide, and fat trim components. Apparent mineral retention (Ca, P, Mg, K, and S) within the body was calculated as the difference between mineral concentration at slaughter and day 0. Mineral concentration at day 0 was determined from body composition of steers harvested at day 0 multiplied by individual live body weight (BW) at day 0. All data were analyzed as a 2 × 11 factorial arrangement with individual animal as the experimental unit. Orthogonal contrasts were used to analyze linear and quadratic contrasts over time (11 slaughter dates). There were no differences in concentration of Ca, P, and Mg in bone tissue as feeding duration increased (P ≥ 0.89); concentration of K, Mg, and S in lean tissue did fluctuate across DOF (P < 0.01). Averaged across treatment and DOF, 99% of Ca, 92% of P, 78% of Mg, and 23% of S present in the body were in bone tissue; 67% of K and 49% of S were in lean tissue. Expressed as gram per day, apparent retention of all minerals decreased linearly across DOF (P < 0.01). Expressed relative to empty body weight (EBW) gain, apparent Ca, P, and K retention decreased linearly as BW increased (P < 0.01) whereas Mg and S increased linearly (P < 0.01). Apparent retention of Ca was greater for CON cattle (greater bone fraction) and apparent retention of K was greater for ZH cattle (greater muscle fraction) when expressed relative to EBW gain (P ≤ 0.02), demonstrating the increase in lean gain by ZH cattle. There were no differences in apparent retention of Ca, P, Mg, K, or S due to treatment (P ≥ 0.14) or time (P ≥ 0.11) when expressed relative to protein gain. Apparent retention averaged 14.4 g Ca, 7.5 g P, 0.45 g Mg, 1.3 g K, and 1.0 g S/100 g protein gain. Expressing apparent mineral retention on a protein gain basis minimized effects of rate and type of gain, allowing for better comparison across treatments and time. Feeding zilpaterol hydrochloride did not affect apparent mineral retention when expressed relative to protein gain.

Mineral requirements for feedlot cattle are largely based on measured mineral concentration in the body at harvest. Fairly extensive research has been done quantifying Ca and P in the body of cattle, but data on Mg, K, and S are sparse. Serial harvest experiments are expensive and labor intensive and therefore not conducted frequently. A group of 115 Holstein steers was fed a finishing diet with serial harvest every 28 d. Two treatments were evaluated, control and cattle fed zilpaterol hydrochloride to increase lean tissue growth. Every 28 d, five steers from each treatment group were harvested with the whole carcass divided into lean, bone, internal cavity, hide, and fat trim components. Apparent mineral retention was calculated as the difference between mineral composition at day 0 (baseline harvest group) and each 28 d harvest group. Averaged across treatment and days on feed, 99% of Ca, 92% of P, 78% of Mg, and 23% of S present in the body were measured in bone tissue; 67% of K and 49% of S were in lean tissue. Apparent retention averaged 14.4 g Ca, 7.5 g P, 0.45 g Mg, 1.3 g K, and 1.0 g S/100 g protein gain.

Live and carcass production traits for progeny of purebred sires in comparison with the clone of a USDA prime yield grade one carcass.

Cloning is a technology by which an animal's tissue can be salvaged and replicated. Carcasses that grade USDA prime-yield grade 1 (P1) represent a rare and antagonistic outcome and are a goal for terminal sire selection in the United States. A terminal sire progeny test generated offspring for a crossbred bull (14% Zebu, 86% Angus; ALPHA), born in 2012 via somatic cell nuclear transfer (SCNT) from a carcass that graded P1. ALPHA progeny (steers and heifers) were compared against progeny of three purebred (Angus; Charolais; Simmental) reference sires. Live production traits included weaning weight, morbidity, mortality, and days on feed; carcass traits included abscessed liver frequency and lung lesion frequency, individual quality and yield grade (YG) parameters, and carcass value. Observed carcass traits for progeny from the Angus, Charolais, and Simmental sires were reflective of the carcass outcomes expected for each sire's respective breed. Calves sired by the Angus were the earliest maturing indicated by the youngest chronological age at harvest (P ≤ 0.02) concomitant with the most backfat (P < 0.01), and the greatest marbling scores (P < 0.01). Calves sired by the Charolais had the heaviest carcass weight (P = 0.04), greatest cutability as assessed by USDA calculated YG (P < 0.01) and were the heaviest muscled based on "longissimus" muscle area (P < 0.01). ALPHA-sired calves were the most similar in carcass outcomes to calves sired by the Simmental, combining advantageous quality and yield parameters to produce an intermediate for carcass quality and yield. The economic value of moderate carcass outcomes is reflected in the carcass value per century weight, in which ALPHA-sired steers tended (P = 0.07) to be of the greatest value compared to other sire groups. ALPHA progeny performed comparably to high-performing reference sires for terminal sire production traits and the P1 genetics in which ALPHA was cloned have economical and biological value in modern U.S. beef production.

Relationship between live body condition score and carcass fat measures in equine.

Relationships between live body condition score (BCS) and carcass fat depots have not been well established in equine. Our study was designed to quantify the relationship between BCS and fat depot measurements from equine carcasses. Live horses (n = 429) were evaluated immediately prior to immobilization at a commercial equine processor. Horses were independently assigned a BCS by a panel of three trained evaluators; BCS was evaluated by visual appraisal and manual palpation of the neck, withers, back, ribs, behind the shoulder, and tailhead. Median BCS frequencies were: 3.0 (n = 9), 4.0 (n = 43), 5.0 (n = 116), 6.0 (n = 86), 7.0 (n = 72), 8.0 (n = 76), and 9.0 (n = 27). Sex (stallion [n = 5], mare [n = 159], or gelding [n = 114]) and breed type (draft [n = 56], stock [n = 363], pony [n = 8], or mule [n =3]) were also denoted. Horses were processed for human consumption according to industry-accepted procedures under the supervision of the Canadian Food Inspection Agency. During the harvest process, all kidney-pelvic-heart (KPH) fat was trimmed from the carcass and weighed. After chilling, the marbling score was subjectively evaluated using beef grading standards. Carcass fat trim was weighed during the fabrication process. As BCS increased, hot carcass weight (HCW), absolute KPH weight, KPH expressed as a percentage of HCW, marbling score, neck fat depth, absolute weight of trimmed carcass fat, and trimmed carcass fat as a percentage of HCW increased (P < 0.01). A strong correlation (r = 0.74; P < 0.01) was detected between BCS and absolute KPH weight. Similarly, correlations between BCS and percentage of KPH (r = 0.65), neck fat depth (r = 0.60), absolute trimmed carcass fat (r = 0.58), trimmed carcass fat as a percentage of HCW (r = 0.54), marbling score (r = 0.54), and HCW (r = 0.52) were also detected (P < 0.01). These data indicate a strong relationship between subjective live BCS and objectively measured carcass fat depots in various equine breed types and sexes.

The effect of zilpaterol hydrochloride on beef producer and processor revenue of calf-fed Holstein steers.

A serial harvest was conducted every 28 d from 254 to 534 days on feed (DOF) to quantify changes in growth and composition of calf-fed Holstein steers (n = 110, initial BW = 449.2 ± 19.9 kg). One-half were supplemented the ß-2 adrenergic agonist zilpaterol hydrochloride (ZH; 8.33 mg/kg 100% DM basis), and the remainder fed a control (CON) ration during the final 20 d followed by a 3 d withdrawal prior to harvest. Cattle were randomly allocated to dietary treatment and harvest endpoint (254, 282, 310, 338, 366, 394, 422, 450, 478, 506, and 534 DOF) using a 2 × 11 factorial treatment structure and a completely randomized experimental design structure. The objective of this ad-hoc investigation was to quantify changes in value across multiple harvest endpoints and marketing strategies for cattle supplemented with ZH. Cattle-fed ZH had increased (P < 0.01) value when sold on a dressed basis (+$82.64) or on a value-based formula (+$75.59) compared with CON cattle. No differences (P ≥ 0.14) were detected between ZH and CON carcasses for premiums and discounts related to HCW, yield grade, or quality grade. Moreover, no differences (P = 0.98) were detected for overall adjusted carcass value between ZH and CON carcasses. Fabrication values revealed that ZH carcasses had greater (P < 0.01) revenue than CON carcasses for primal round (+$36.23), loin (+$38.16), flank (+$8.95), rib (+$16.33), and chuck (+$27.49) regardless of DOF. Increased primal values ultimately led to greater (P < 0.01) processor revenue (+$138.94) and carcass value per 45.4 kg (+$6.45) for cattle-fed ZH compared with CON cattle. Overall, increased carcass weight and improved fabrication yield led to greater revenue at all harvest endpoints for cattle-fed ZH. Linear increases in live and dressed values indicated the daily change in live value was $3.48, which is less than an increase of $3.77 daily for dressed carcass value. Greater beef processor margin and profitability are expected when this growth technology is used.