Estrus in Range Lambs and Its Relationship to Lifetime Reproductive Performance

Hulet, C. V.; Wiggins, E. L.; Ercanbrack, S. K.

doi:10.2527/jas1969.282246x

Cited by 34 publications

(17 citation statements)

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“…Hulet, Wiggins and Ercanbrack (1969) and Hight and Jury (1976) found that occurrence of oestrus in young ewes was associated with a greater proportion of ewes lambing and a higher incidence of multiple births later in life. However, as stated earlier, the differences were not significant.…”

Section: Discussionmentioning

confidence: 99%

Production in mature corriedale ewes first mated at 7 to 11 or 18 months of age

Ponzoni¹,

Azzarini²,

Walker³

1979

Anim. Sci.

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Production in 210 mature Corriedale ewes first mated between 7 and 11 or at 18 months of age was studied at Paysandu, Uruguay. Ewes were classified into one of the following five classes according to their oestrous and lambing performance in 1968: (1) reared a lamb; (2) lambed but lamb died; (3) mated but did not lamb; (4) oestrus detected by vasectomized ram, true mating deferred for 12 months; and (4) no oestrus, mating deferred for 12 months. Records on flock performance and mortality were kept from all ewes from 1969 to 1973, when the dental status of all ewes present was assessed. There were no significant differences between classes in number of ewes lambing per ewe exposed to the ram, number of lambs born per ewe exposed to the ram, number of lambs weaned per ewe exposed to the ram, weight of lamb weaned per ewe exposed to the ram, and pre-mating body weight. Greasy fleece weight varied significantly (P<0-01) with class of ewe. The least squares means for ewe classes 1 to 5 were 3-93, 3-99, 4-06,4-12 and 3-92 kg respectively. Class 4 ewes differed significantly (/ > <0-01) from class 1 ewes and from class 2, 3 and 5 ewes (i > <0-05). Class 3 ewes differed significantly (/ > <0-05) from class 1 ewes. Other differences were not significant. Ewe mortality between 1969 and 1973 was independent of class of ewe. The dental status of ewes appeared to vary with class of ewe. Early mating of Corriedale ewes apparently had no adverse effects on mature reproductive performance, but somewhat reduced wool production. If mating is to take place for the first time at 18 months of age, ewes that have shown oestrus previously are likely to exhibit greater overall productivity (wool plus lambs).

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Section: Discussionmentioning

confidence: 99%

Production in mature corriedale ewes first mated at 7 to 11 or 18 months of age

Ponzoni¹,

Azzarini²,

Walker³

1979

Anim. Sci.

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Section: Introductionmentioning

confidence: 99%

“…Sexual maturation and its onset signals the start of an animals reproductive life and is a trait of profound importance from both an evolutionary and economic perspective. The earlier the onset of maturation, the greater the total potential offspring production, and hence commensurate gains in fitness (Hulet et al 1969). It is therefore of no great surprise that the domestication process has served to decrease the time taken to reach sexual maturation, with examples in numerous different animals [including chicken (Etches 1996), sheep (Tchernov andHorwitz 1991) and dogs (Morey 1994)].…”

Section: Introductionmentioning

confidence: 99%

Onset of Sexual Maturity in Female Chickens is Genetically Linked to Loci Associated with Fecundity and a Sexual Ornament

Wright

Rubin

Schütz

et al. 2011

Reprod Domestic Animals

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Trait Loci (QTL) analysis (n=377) was performed using an F 2 intercross between a White Leghorn layer breed and a Red Junglefowl population, with onset of sexual maturity measured and mapped to three separate loci. This cross has already been analysed for comb mass, egg production and bone allocation. Onset of sexual maturity significantly correlated with comb mass, whilst the genetic architecture for sexual maturity and comb mass overlapped at all three loci. For two of these loci the QTL for sexual maturity and comb mass were statistically indistinguishable from pleiotropy, suggesting that the alleles that increase comb mass also decrease onset of sexual maturity.3

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“…The occurrence of hogget oestrus was associated with both an increase in the proportion of ewes lambing and multiple birth rate, particularly at 2 years of age. The positive association between the occurrence of hogget oestrus and ewe fertility is supported by Wiggins (1955), andHulet et al (1969), who also found that the increased ewe fertility resulted from a higher proportion of ewes lambing and increased multiple birth rate. Ch'ang andRae (1970, 1972) reported that the number of hogget oestrous cycles was positively correlated both phenotypically and genetically with the percentage of lambs born over three ewe Iambings.…”

Section: Discussionmentioning

confidence: 76%