Influence of Nutritional Status on Hormone-Induced Superovulation in Normally Cycling Ewes

Tait, R. M.

doi:10.4141/cjas71-104

Cited by 4 publications

(3 citation statements)

References 4 publications

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“…In two of three experiments the ovarian response to a constant dose of PMSG was significantly greater in the heavier ewes. These data are in agreement with the present work where differential feeding was for 15 weeks, and consequent live-weight differences were much greater than those reported by Tait (1971). Differences in ovarian response between high-plane and low-plane ewes could be due to the ovaries of the lighter animals being less sensitive to a fixed amount of circulating gonadotrophin and/or due to a reduction of pituitary output in these animals.…”

Section: Oestrus and Ovulationsupporting

confidence: 92%

“…As well as the effects of nutrition and body weight on ovulation rate, administration of gonadotrophins during the follicular phase of the cycle will induce multiple ovulations and increase number of lambs born (Robinson 1951a(Robinson , 1961Wallace 1955;Gordon 1958;Wallace et al 1954). However, of the early workers only (PMSG) in agreement with the more recent report of Tait (1971). In ewes treated with progestagens plus PMSG in the non breeding season restriction of feeding with resultant decreases in live weight has been shown to decrease ovulation rate (Keane 1973).…”

Section: Introductionsupporting

confidence: 73%

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Effect of nutritionally induced live-weight differences on the ovarian response and fertility in ewes treated with pregnant mare's serum gonadotrophin

Allison¹

1975

New Zealand Journal of Agricultural Research

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Two groups of 120 Romney ewes were differentially fed for 4 months resulting in a mean live-weight difference of 15 kg. Within groups, ewes were treated with 0, 600, or 1000 i.u. pregnant mare's serum gonadotrophin (PMSG), on day 13 of the cycle. Ewes were mated with entire rams and were slaughtered 22-24 days later to assesss ovulation rates and the number of normal embryos. Ewes returning to service were slaughtered 1 to 4 days later to determine fertilisation rates. Treatment with PMSG increased the ovulation rate (p < 0.01) and the response was greater in the heavier ewes (p < 0.01). Mean ovulation rates were 1.35, 1.97, and 3.88 in low-live-weight ewes and 1.54, 2.95, and 5.34 in high•live•weight ewes ireated with 0, 600, or 1000 i.u. respectively. Conception rates did not differ significantly between the treatment groups and also did not differ between ewes shedding different numbers of ova. In those ewes not returning to service the mean number of normal embryos was 1.23, 1.64, and 2.08; and 1.37, 2.07, and 2.37 for low-and high-live-weight ewes treated with 0, 600, or 1000 Lu. PMSG respectively. As the number of ovulations increased the proportion of embryonic mortality also increased.

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Section: Oestrus and Ovulationsupporting

confidence: 92%

Section: Introductionsupporting

confidence: 73%

Effect of nutritionally induced live-weight differences on the ovarian response and fertility in ewes treated with pregnant mare's serum gonadotrophin

Allison¹

1975

New Zealand Journal of Agricultural Research

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“…The conception rate to first service was reduced 16% after PMSG treatment. This has also been noted by Robinson (1951) and Allison (1973), but other workers have reported no real decrease after PMSG administration (Wallace 1954;Gordon 1963;Tait 1971).…”

Section: Discussionsupporting

confidence: 76%

Reproductive differences in two-year-old Romney and Border Leicester ×Romney ewes after gonadotrophin treatment

Eastwood

McDonald

1975

New Zealand Journal of Agricultural Research

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Two hundred and seven Romney and first-cross Border-Romney 2-year-old ewes were glazed for 2 months at two planes of nutrition and treated with 0, 600, or 1200 Lu. pregnant mares' serum gonadotrophin (PMSG). Ewes were mated to Southdown rams after treatment and for a further two succeeding oestrous cycles. Each ewe was laparotomised within a week of injection and the number of fresh ovulations recorded. The number of lambs born was noted. High-plane ewes gained 1.39 kg and low-plane ewes lost 1.51 kg over the 2-month period. The crossbred ewes had higher natural ovulation rates, lambing performances, and responses to PMSG. PMSG reduced (16%) the conception rate at first service, proportionately more ewes returning to service at prolonged intervals (> 20 days), and this "carryover" effect reduced the incidence of ewes that subsequently became pregnant. The proportion of "potential lambs" born was related to ovulation rate through dose of PMSG and breed. Litter size increased with up to five ovulations per ewe despite an increasing percentage of potential lambs lost. Nutrition had no effect on natural ovulation rates or response to PMSG. It is concluded that lambing performance in these breeds is limited by natural ovulation rate, as a higher uterine capacity exists in both breeds.

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Effects of short and long – term nutrition and progesterone supplementation on the success of fixed – time artificial insemination in the ewe

Kleemann,

Kelly,

Foyster

et al. 2024

Animal Reproduction Science

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Influence of Nutritional Status on Hormone-Induced Superovulation in Normally Cycling Ewes

Abstract: Two groups, e_ach oJ 18 no,rmally cycling ewes, pMS, respectively, and 2.10 and 1.44 for the were subjected to.eirher alowplan-e f .9 ]r4"u! irigh plani group,'with ina witnoui prvrS

Cited by 4 publications

References 4 publications

Effect of nutritionally induced live-weight differences on the ovarian response and fertility in ewes treated with pregnant mare's serum gonadotrophin

Effect of nutritionally induced live-weight differences on the ovarian response and fertility in ewes treated with pregnant mare's serum gonadotrophin

Reproductive differences in two-year-old Romney and Border Leicester ×Romney ewes after gonadotrophin treatment

Effects of short and long – term nutrition and progesterone supplementation on the success of fixed – time artificial insemination in the ewe

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