Effect of zeranol implants in ram and wether lambs on performance traits, carcass characteristics, and subprimal cut yields and distribution1

Abstract

In two separate 2 x 2 factorial arrangements, 69 male, crossbred lambs were allotted randomly to the following treatments: 1) nonimplanted (NI) rams, 2) implanted (I) rams, 3) NI wethers, and 4) I wethers. In Trial 1, 36 lambs were allotted to treatment groups at birth (n = 9) and I lambs were implanted with 12 mg of zeranol between 1 and 3 d of age and again at weaning (average age of 62 d). Lambs were slaughtered at three time-constant end points of 78, 93, and 107 d on feed postweaning (average age of 155 d). Rams grew faster postweaning, were more efficient in their feed conversion, were heavier at slaughter, and had lower numerical yield grades than did wethers (P less than .05). Implanted lambs tended (P = .08) to grow faster and were (P less than .05) more efficient in their feed conversion than NI lambs. Rams produced heavier (P less than .05) trimmed subprimal shoulders, loins, and legs and had (P less than .05) a higher percentage of their carcass weight in the subprimal shoulder than did wethers. During Trial 2, NI rams (n = 8), I rams (n = 8), NI wethers (n = 8), and I wethers (n = 9) were allotted to treatment groups, and I lambs were implanted at average ages of 14, 55, and 98 d. After weaning, lambs were weighed every 14 d and were slaughtered 7 d after reaching a minimum weight of 50 kg (average age of 148 d).(ABSTRACT TRUNCATED AT 250 WORDS)

Productive performance, composition and carcass yield of lambs treated with zeranol

“…Previous research indicates that FG can be improved by implanting lambs twice with 12 mg of zeranol (Nold et al, 1992), and both FG and ADG can be improved by implanting lambs with 12 mg of zeranol 3 or more times (Hufstedler et al, 1996). Domínguez et al (2010) reported that lambs implanted with 24 mg zeranol had increased FG compared with lambs implanted with 12 mg zeranol or with no implantation.…”

Effect of Implant Different Levels of Zeranol on Growth Performance, Carcass Trait and Body Composition of Awassi Lambs

“…Such reduction in testicular weight amounted to 38.1 and 47.8% in lambs treated with 12 and 24 mg zeranol, respectively. Similarly, weight of testes was reduced approximately 50% by implanting lambs with 12 mg zeranol ( Field et al, 1993) and Nold ( 1990 ) who reported implanting lambs at birth and again at weaning reduced testicle weight by 25%. Also, decreased testicular weight (Calkins et al, 1986 ), epididymal weight, seminiferous tubule diameter and testosterone ( Calkins et al, 1986;Nold et al, 1992) have been observed in lambs implanted with zeranol post weaning.…”

“…Similarly, weight of testes was reduced approximately 50% by implanting lambs with 12 mg zeranol ( Field et al, 1993) and Nold ( 1990 ) who reported implanting lambs at birth and again at weaning reduced testicle weight by 25%. Also, decreased testicular weight (Calkins et al, 1986 ), epididymal weight, seminiferous tubule diameter and testosterone ( Calkins et al, 1986;Nold et al, 1992) have been observed in lambs implanted with zeranol post weaning. It has been suggested that the action of the estradiol implant is mediated through changes in luteinizing hormone secretion (D,Occhio et al, 1984), or by blocking gonadotropin release at the level of hypothalamus .…”

“…Furthermore, zeranol implant has been noticed to increase daily gain in weight in rams (Wilson et al, 1972) andlambs (Landau et al, 1987). Also an improvement in feed efficiency was noticed as a result of implanting lambs with zeranol (Wiggins et al, 1979, Hutcheson et al, 1992, Nold et al, 1992, Salisbury et al, 2007, and steers (Williams et al, 1987). Earlier work on the effect of zeranol implantation on growth performance and carcass traits of Awassi and Karadi lambs conducted during the hottest months (May-July) of the year revealed that a slight response of the two breeds to zeranol implantation in all studied traits was observed (Alkass and Kak, 2015) However, Calhoun et al (1972) concluded that the response of lambs to zeranol implantation was lower during summer in Texas as compared to response in winter.…”

Ultrasound Imaging to Estimate Carcass Quality of Pasundan Cattle based on Body Condition Score

“…Factors taken into account in assessing meat and carcass quality in cattle according to USDA standards include carcass weight, carcass length, backfat thickness, longissimus dorsi muscle thickness, pelvic fat percentage, marbling score, and fat color (Nold et al 1992). Ultrasound imaging has been used since 1960 to measure muscle fat thickness in beef cattle which is a parameter in the Quality Beef Contest at the International Livestock Exposition (Stouffer 2004).…”