Effects of sex and gonadectomy on the growth and development of Southdown × Romney cross lambs. Part I. Effects on live–weight growth and components of live weight

Everitt, G. C.; Jury, K. E.

doi:10.1017/s0021859600060238

Cited by 28 publications

(12 citation statements)

References 21 publications

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“…The effects of sex and castration on carcass composition of Omani sheep were consistent with findings reported for temperate (Everitt and Jury, 1966;Butterfield, 1988) and tropical (Gaili and Mahgoub, 1981) breeds. Weights of non-carcass components were higher and DO was lower in rams than in wether and ewe lambs, especially at higher live weights, probably because of differences in fatness (Kirton and Morris, 1989).…”

Section: Body Compositionsupporting

confidence: 87%

Growth and body composition of Omani local sheep 1. Live-weight growth and carcass and non-carcass characteristics

Mahgoub

Lodge

1994

Anim. Sci.

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Forty-five local Omani ram, wether and ewe lambs were reared from birth until slaughter at 18, 28 or 38 kg live weight (five of each 'sex' at each weight group) on an ad libitum concentrate diet and Rhodesgrass hay. Ram lambs grew faster from birth and reached -predetermined slaughter weights earlier than wether and ewe lambs. At 28 kg live weight, ram lambs had: heavier heads, feet, reticulo-rumens and livers; higher muscle and bone and lower fat proportions in the carcass; lower muscle : bone and higher muscle : fat ratios; higher proportions of carcass but lower non-carcass fat than had wether and ewe lambs. The head, feet, alimentary tract, liver and heart of Omani sheep grew at a lower rate; the skin grew at a similar rate and the carcass grew at a rate faster than empty body weight (EBW). Relative to EBW, muscle grew at a similar rate, fat faster and bone slower. Both carcass and noncarcass fats grew at a rate higher than that of the growth of EBW, with non-carcass fat growing at a higher rate than that of carcass fat. The growth rate of omental fat was the fastest followed by kidney, mesenteric, subcutaneous, tail, scrotal, intermuscular and pelvic fats respectively.This study demonstrated that Omani sheep have good potential for growth if they are managed and fed satisfactorily. Omani sheep are early maturing for which reason it is recommended that they be slaughtered at lighter weights to avoid higher fat content in the carcass. Castration in Omani sheep is not recommended for production of meat lambs under intensive systems as it resulted in reduced growth rates and deposition of excess fat at lower slaughter weights.

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Section: Body Compositionsupporting

confidence: 87%

Growth and body composition of Omani local sheep 1. Live-weight growth and carcass and non-carcass characteristics

Mahgoub

Lodge

1994

Anim. Sci.

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“…Growth of the internal organs of the sheep has been studied by several workers (Hammond and Appleton 1932;Wallace 1948;Palsson and Verges 1952;Wardrop and Coombe 1960;Wardrop 1960;Everitt and Jury 1966) whose results could be expected to conform to the general growth relationships for mammals reported by Brody (1945). The use of organ weights for predicting the fat-free carcass or muscle weight in sheep was investigated by Kirton (1957) in a manner similar to that suggested by Kraybill, Hiner, and Farnworth (1954) for predicting the lean body mass and empty body weight in cattle.…”

Section: Introductionmentioning

confidence: 96%

Growth and development of sheep

Kirton

Fourie

Jury

1972

New Zealand Journal of Agricultural Research

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The growth of the hot carcass and some non-carcass components of 212 rams and ewes of the Romney and Southdown breeds and their cross was obtained from a comparative slaughter trial. Samples were slaughtered at birth, at 1, 6, 11, 16, 25, 41, and 80 weeks of age, and at maturity. Allometric growth coefficients are presented relating component weight to starved body weight together with estimates of component weights for the different breeds and sexes at 5, 10, 20, 30, 40, and 55 kg live weight. The growth of the fat depots and the stomach (excluding the abomasum) was markedly faster than that of the starved body weight, and the growth of most of the reproductive tract was moderately faster. The remaining body parts grew at rates similar to, or slower than, starved body weight.

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“…Everitt & Jury (1966) reported depression in growth in castrated lambs, but only at the 10% level of probability. In Experiment 1 of the pres¬ ent study, control lambs were significantly heavier than the castrated group from birth, even though the two groups were selected into their treatment groups at random.…”

Section: Discussionmentioning

confidence: 96%

Early prenatal treatment of ewes with testosterone completely masculinises external genitalia of female offspring but has no effects on early body weight changes

Tarttelin

1986

Acta Endocrinologica

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Treatment of pregnant ewes from day 20 of gestation with 100 mg implants of crystalline testosterone did not cause masculinisation of genitalia or affect growth rates of female lambs. Prenatal treatment from day 20 of gestation with testosterone propionate (1.2 g in divided doses for four weeks) or testosterone cypionate (600 mg in 3 doses over three weeks) completely masculinised the external genitalia of female lambs producing a ventral penis and scrotum with no external vaginal opening: ovaries and uteri were normal. Single male lambs were significantly heavier than female lambs during a 16 week measurement period, but masculinised female lambs were not different from controls. In the twin lamb groups, there were no differences between male and female or treated and control lambs. Body weights of castrated male lambs born as twins were not different from entire controls. It was concluded that testosterone treatment of developing lambs from 20 to 65 days of gestation produces complete masculinisation of external genitalia of female lambs but does not affect body weight during the first 16 weeks of age.

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Effects of sex and gonadectomy on the growth and development of Southdown × Romney cross lambs. Part I. Effects on live–weight growth and components of live weight

Cited by 28 publications

References 21 publications

Growth and body composition of Omani local sheep 1. Live-weight growth and carcass and non-carcass characteristics

Growth and body composition of Omani local sheep 1. Live-weight growth and carcass and non-carcass characteristics

Growth and development of sheep

Early prenatal treatment of ewes with testosterone completely masculinises external genitalia of female offspring but has no effects on early body weight changes

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