Growth and development of sheep

Abstract

Individual muscles were dissected from the carcasses of 212 rams and ewes of the Romney and Southdown breeds and their cross in a comparative slaughter trial. Sample animals were slaughtered at birth and 1,6, 11, 16,25,41, and 80 weeks of age and at maturity. Allometric growth coefficients are presented for the individual muscles and for nine muscle groups, individual muscle growth being related to total muscle growth and coefficients being compared between breeds and between sexes. Coefficients differed significantly between breeds and between sexes for some muscles and muscle groups. The effect of different relative growth rates (and constants) on the proportions of the various muscles and muscle groups at selected total muscle weights is reported. The breed effects on individual muscle growth. although significant, tend to average out so that, where present, these differences result in minimal differences between breeds in the proportions of muscle in the different groups. The large differences in conformation noted by the meat trade between Romney and the Southdown-Southdown Romney cross are not reflected by a markedly better distribution of the more valuable muscles in the blockier Southdown type carcass. 115

Breed and sex differences in equally mature sheep and goats 3. Muscle weight distribution

“…However, m. semitendinosus, m. semimembranosus and m. quadriceps femoris each had b values significantly less than 1-0 and q values significantly greater than 1-0 (Table 3) so that, in general, this muscle group appeared to be early maturing. The results of Lohse et al (1971), Lohse (1973) and Jury et al (1977) were in general agreement but they found m. semitendinosus and mm. gluteus slightly late maturing.…”

“…M. longissimus thoracis et lumborum, which is about six times heavier than m. iliopsoas, had a b value not significantly different from 1-0 and a q value significantly less than 1-0 (Table 3). This is at variance with its classification as early maturing in the studies of Jury et al (1977), Lohse et al (1971) and Butterfield et al (1983b and1984a).…”

“…For the same twelve muscles, the average q values of 1-23 from Butterfield et al (1983a and1984a) implied they were even earlier maturing. However, the b values of Lohse et al (1971) and Jury et al (1977), which were both 0-97, implied a smaller differences in maturing rate between higher and lower-priced muscles.…”

“…The complete set of group 2 muscles dissected by Butterfield's group had q values of 1-30 for Merino and 1-19 for Dorset Horn sheep. The b values of Lohse et al (1971) and Jury et al (1977) were 0-87 and 0-76 for m. gastrocnemius. With only two of the 10 muscles in this group, the average q value in Table 3 was about 1-39 and the b value averaged 0-81 (both significantly different from 1-0) so that the distal hindlimb muscles are consistently found to be early maturing.…”

Variabilité de la répartition du tissu musculaire du membre postérieur de l'agneau. — I. Muscles individuels

“…La musculature striée des animaux est un (Hammond, 1932 ;Pàlsson, 1940 ; Dumont, 1960 ;Boccard et al, 1961 ;Fourie, 1965 ; Dumont, 1973 ;Jackson et Mansour, 1974 ;Jury, Fourie et Kirton, 1977 ;Anous, 1980 ;Taylor, Mason et McClelland, 1980 ; Thorgeirsson, 1981 ;Teyssier et Prud 'hon, 1982 ;Butterfield et al, 1983 ;Butler-Hogg et Whelehan, 1984 ;Butterfield et al, 1984). Mais dans cette espèce, comme dans les autres, on manque d'information sur l'amplitude de la variation rencontrée entre individus présentant des types morphologiques très différents et chez lesquels on sait maintenant qu'il existe des contraintes particulières du développement musculaire en liaison avec la masse et les dimensions des supports osseux (Anous, 1986a fig.…”