Response to selection for multiple births in the Australian Merino: a progress report

Turner, Helen; Hayman, RH; Triffitt, L. K.; Prunster, R. W.

doi:10.1017/s0003356100034486

Cited by 18 publications

(8 citation statements)

References 6 publications

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“…In this respect they are similar to most previous estimates reported in the literature and reviewed by Turner et al (1962). In this respect they are similar to most previous estimates reported in the literature and reviewed by Turner et al (1962).…”

Section: Discussionsupporting

confidence: 92%

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Repeatability and heritability of fertility in hill sheep

Purser¹

1965

Anim. Sci.

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SUMMARYLambing records of 3,500 Scottish Blackface ewes and 2,000 Welsh Mountain ewes were used for a study of repeatability of ewe fertility and litter size. The repeatability of litter size at birth (calculated as an intra-ewe correlation) was higher in both flocks (0.19 and 0.24 for Blackface and Welsh ewes respectively) than that for barrenness (0.09 and 0.08) or for number of lambs born per mating (0.07 and 0.10). Repeatability of the corresponding traits at weaning were generally about half these values.About two-thirds of the ewes had sires recorded and were used for a heritability analysis. The heritability of litter size at birth in both flocks was higher (0.14 and 0.16 for Blackface and Welsh respectively) than either the heritability of barrenness (−0.03 and 0.03) or of numbers of lambs born per mating (−0.01 and 0.07).It was concluded that the greatest improvement in numbers of lambs weaned would be obtained by selection on litter size at birth. There would be correlated changes in live-weight (genetic correlations of 0.44 and 0.78 for Blackface and Welsh respectively) but not in fleece weight (genetic correlations of 0.09 and −0.13).

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Section: Discussionsupporting

confidence: 92%

“…Estimates of heritability of numbers of lambs born in sheep have recently been reviewed by Young, Turner and Dolling (1963) and Turner et al (1962). In sheep, as in other livestock, this character is also of economic importance and consequently may be subject to some artificial selection.…”

Section: Arc Animal Breeding Research Organisation Edinburghmentioning

confidence: 99%

Repeatability and heritability of fertility in hill sheep

Purser¹

1965

Anim. Sci.

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“…The response has been described by Turner et al (1962) and Turner (1966Turner ( , 1968Turner ( , 1969 in Peppin Merinos in which the difference in lambing rate appears to be due primarily to a correlated response in natural ovulation rate. Mean differences between groups selected for and against multiple births vary from 0·4 to 0·9 corpus luteum for ewes of various ages (Packham and Triffitt 1966;Bindon et al 1971;Trounson and Moore 1972).…”

Section: Introductionmentioning

confidence: 92%

“…The lambs used in this study were progeny of the Peppin Merino selection groups described by Turner et al (1962). Selection had either been for (T group) or against (0 group) the incidence of multiple births.…”

Section: Animalsmentioning

confidence: 99%

Primordial Follicle Numbers in Ovaries and Levels of LH and FSH in Pituitaries and Plasma of Lambs Selected for and against Multiple Births

Trounson¹,

Wa²,

Kennedy³

et al. 1974

Aust. Jnl. Of Bio. Sci.

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The numbers of primordial follicles in ovaries of ewe lambs, from two groups of Peppin Merinos that had been selected for (T group) and against (0 group) mUltiple births, were estimated at birth, 7 days and 5 months of age. Peripheral plasma and anterior pituitary levels of LH and FSH were determined by radioimmunoassay in the lambs at 5 months of age. These lambs were either entire or unilaterally ovariectomized (hemispayed) at 7 days of age.There was no difference in primordial follicle numbers between lambs at birth and 7 days of age, but when paired ovaries of hemispayed lambs at 7 days and 5 months of age were compared there was a significant increase in follicle numbers with age (34903 v. 48047). O-group lambs had more primordial follicles than T-group lambs at birth and 7 days of age (65501 v. 37797) and there was a similar but not significant difference at 5 months of age (53934 v. 44057).Peripheral plasma LH was higher in T-group than in O-group lambs and plasma LH levels were correlated to pituitary LH content (r = o· 75). Vesicular follicles larger than 2 mm in diameter were present only in ovaries of lambs with plasma LH levels above 3· 0 ng/m!. Pituitary FSH levels were considerably higher in hemispayed lambs than in entire lambs and there was a trend to higher levels in T-group lambs when compared with O-group lambs.It is concluded that genetic selection for the incidence of multiple births has resulted in changes in the number of ovarian primordial follicles of the post-natal lamb and it is suggested that these changes may be related to the levels of pituitary gonadotrophins.

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“…Several authors (4,8,11,Zl) reported that the sire had little or no effect on litter size, while others (t,2,9, lO, 1.2, 14) reported a ,significant sire efiect. Sire influences on litter size have been shown in mice (5, 6;13) and sheep (18,20). In cattle, a direct eftect of the sire on bfuth rate has been reported (7).…”

Section: Introductionmentioning

confidence: 99%

Influence of the Sire on Litter Size in Swine

Rahnefeld¹,

Swierstra²

1970

Can. J. Anim. Sci.

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The direct effect of the sire on the total num-and Lacombe populations there' was a -signi6gr.f pigr-boi" fi""t"Aing-iiittUo.o, exclud-ficant sire efiect on the total number of p-igs ing necioiic), ttre iumbeiSoi"itive, and the born, the_number born alive, and the number ft"-b;i *;;;"4 *"r ii"OOO in 277 Yorkshire weaned. Intra-sire correlations (repeatability) and 356 Lacombe litters iireO by 131 York-for total number born, number born alive, itriie-ana t6j Lacombe boars. Af mating, the and number weaned were 0.174 -f 0.082 uu-"iug" ugeot-ttte maies was 250 -r lddays (P < 0.95)r-0.!63 :-q'0.81--(P-<. 0'05)' and oT thifemales 248 -+-18 days. The Yori<-0.194 -{. 0.081-(4"_< 0.01) in Yorkshires and shire andLaccimbe sires pioduc6d an averase 0.242 -r 0'070 (P < 0'01)'-0'208-t g'gz! ;ft.{l;;d,t.is-titi"tt, ietpeitiuetv. For tfie (P < 0.01), a-ni 0'167 t o.o72 (P-< 0'05) Yorkshire litters the ioiaf'"omUJr of pigs in Lacombes. Linear regression coefficients of born, number born alive, and number *eanJd litter size (num-ber born, number born alive, were' 9.43, 9.07, and 8.i5, respectively. Cor-number wearled) on number of females setresponding averages for tire Gcombes were tled by the sire are presented' 9.09, 8.38, znd 6.97.In both the Yorkshire

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Response to selection for multiple births in the Australian Merino: a progress report

Cited by 18 publications

References 6 publications

Repeatability and heritability of fertility in hill sheep

Repeatability and heritability of fertility in hill sheep

Primordial Follicle Numbers in Ovaries and Levels of LH and FSH in Pituitaries and Plasma of Lambs Selected for and against Multiple Births

Influence of the Sire on Litter Size in Swine

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