Reproduction in Javanese Sheep: Evidence for a Gene with Large Effect on Ovulation Rate and Litter Size1

Abstract

Three breeds of Javanese sheep are described briefly and data suggesting the segregation of a gene with large effect on ovulation rate and litter size are presented. The three breeds are Javanese Thin Tail (JTT), Javanese Fat Tail (JFT) and Semarang (SEM), the last possibly a substrain of JTT. All three breeds have mean mature ewe weights under 30 kg. Ovulation rate and litter size did not differ significantly among the three; all had litter sizes of up to 4 or 5 with a mean for mature ewes of approximately 2. Ovulation rate ranged from 1 to 5 and had an average within-breed repeatability of .8 within season and .65 between seasons. Within-breed repeatability of litter size was .35 +/- .06. Prenatal survival in pregnant ewes with two, three and four or more ovulations averaged 93, 88 and 86% over two seasons. Dams that had at least one ovulation rate or litter size record greater than or equal to 3 produced two groups of daughters in approximately equal numbers: one group with many records greater than or equal to 3 and mean ovulation rate and litter size of 2.73 and 2.31, respectively, and one group with ovulation rates and litter sizes of 1 or 2 and corresponding means of 1.39 and 1.38. Dams with ovulation rate or litter size records of only 1 or 2 produced daughters in which over 90% had records of only 1 or 2. Estimated heritabilities for the mean of approximately three ovulation rate or litter size records from these daughter-dam comparisons exceeded .7. These results suggest segregation of a Booroola-type gene, one copy of which increases ovulation rate by about 1.3 and litter size by .9 to 1.0. Relationships between duration of estrus and ovulation rate, and between timing of release of luteinizing hormone and number of eggs shed, resemble the pattern in Booroola Merino more closely than that in Finnish Landrace or Romanov, supporting the hypothesis of a major gene.

Selection of Black Bengal Buck Based on Some Reproductive Performance of Their Progeny at Semi-Intensive Rearing System

“…Within a production or management system, the phenotypic variation of a composite trait is influenced by the level of variability among its component traits and their interactions (Snowder, 2008). Although component traits of reproduction are under the influence of many genes, a limited number of major genes associated with separate components of reproduction have been reported (Piper & Bindon, 1982;Bradford et al, 1986). Expressions of the genetic effects on reproduction are affected by numerous environmental factors such as season, climatic conditions, management, health, nutrition, breeding ratio, age and weight of doe, and libido of buck and fertility.…”

Segregation of a major gene influencing ovulation in progeny of Lacaune meat sheep

“…Since 1982, when evidence of the first major gene for prolificacy was found by Piper and Bindon [23], and Davis et al [7] in Booroola Merinos, various authors like Hanrahan and Owen [13], Hanrahan [12], Jonmundsson and Adalsteinsson [17], Bradford et al [4], Radomska et al [26], and Davis et al [5] have suspected or demonstrated that ovulation in other sheep breeds could also result from mixed (polygenic background + major gene) inheritance. In addition, Galloway et al [11] have found the DNA mutation responsible for the Inverdale genotype shown by Davis et al [6,8].…”

Genes controlling ovulation rate in sheep

“…In addition to genes in the Booroola (FecB) and Inverdale (FecX) sheep, there is evidence that major genes may be segregating in Icelandic (Johnmudsson and Adalsteinsson, 1985), Javanese (Bradford et al, 1986), Olkuska (Radomska et al, 1988), Cambridge (Owen et al, 1990;Hanrahan, 1991), Belclare (Hanrahan, 1991), Lacaune (Bodin et al, 1998) and Woodlands (Davis et al, 2001) sheep breeds. Some genes in these breeds may represent alleles for a smaller subset of genes.…”