Liveweight, ovulation rate, and wool growth responses of light and heavy ewes to differential feeding

Kelly, Regis B.; Thompson, K. F.; Hawker, H. W.; Crosbie, S. F.; McEwan, John C.

doi:10.1080/03015521.1983.10427758

Cited by 12 publications

(9 citation statements)

References 1 publication

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“…Pasture mass to ground level before grazing was estimated by a double sampling method using a weighted disc meter and quadrat cutting as described by Kelly et al (1983). The mean pasture mass before grazing was 1920 and 2225 kg total DM/ha in Years 1 and 2 respectively.…”

Section: Pasture Measurementsmentioning

confidence: 99%

Effects of pasture allowance in winter on liveweight, wool growth, and wool characteristics of Romney ewes

Hawker

Thompson

1987

New Zealand Journal of Experimental Agriculture

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In each of two years, pasture allowances of 0.7, 1.2, 1.7, or 2.2 kg dry matter (DM)/ewe per day were offered to groups of Romney ewes for 6 weeks in June -July. The ewes were then run together until weaning in December. In Year I there were 70 2-year-old ewes per group; mean initialliveweight was 47 (SE 0.25) kg. In Year 2 each group comprised 25 2-year-old ewes with a mean initialliveweight of 48 (SE 0.49) kg and 25 6-year-old ewes with a mean initial liveweight of 57 kg. For liveweight change (g/day), the inverse linear relationship with pasture allowance (kg DM/ewe per day) for ewes with one lamb in utero was: [liveweight change = 136 (SE 4.4) -(132 (SE 5.0) allowance)]. On average, the pasture allowance that resulted in zero liveweight change was predicted to be 1.0 kg DM/ewe per day. With a pregrazing pasture mass of c. 2000 kg DM/ha, zero liveweight change was associated with a residual pasture mass of 760 kg DM/ha, a utilisation of 660/0, and an apparent intake of 0.59 kg DM/ewe per day. For ewes with zero, one and two lambs in utero, zero liveweight change was predicted to occur on pasture allowances of 1.3, 1.0, and 0.8 kg DM/ewe per day, respectively. However, a similar allowance (c. 1.3 kg DM/ewe per day) would maintain body weight (conceptus free) for ewes in all three categories. Pasture allowance in June -July affected liveweight in August by up to 3.4 kg but this effect had largely disappeared by

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Section: Pasture Measurementsmentioning

confidence: 99%

Effects of pasture allowance in winter on liveweight, wool growth, and wool characteristics of Romney ewes

Hawker

Thompson

1987

New Zealand Journal of Experimental Agriculture

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“…It follows that knowledge of ewe liveweight at key points during the reproductive cycle could be a useful predictor of fleece wool characteristics. In addition, both liveweight at joining and changes in liveweight before joining influence the fertility and fecundity of breeding ewes (Morley et al 1978;Kelly et al 1983; Thompson et al 1985). The nature of the relationships between wool production and reproduction with the change in liveweight of ewes throughout a breeding cycle (liveweight profile) remain largely unknown.…”

Section: Introductionmentioning

confidence: 99%

The wool production and reproduction of Merino ewes can be predicted from changes in liveweight during pregnancy and lactation

Ferguson

Thompson

Gordon³

et al. 2011

Anim. Prod. Sci.

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Abstract. Defining the nature of the relationship between change in liveweight throughout a breeding cycle and ewe wool production and reproduction would be useful for developing management guidelines for Merino ewes. In this paper we tested the hypotheses that (1) feed on offer has variable effects on liveweight profiles of individual ewes; and (2) liveweight profiles of individual ewes can be used to predict their fleece wool production and reproductive performance. At sites in Victoria and Western Australia in 2001 and 2002, pregnant Merino ewes were exposed to 10 nutritional treatments. In each of the four experiments, ewes in average condition score 3 at artificial insemination were fed to achieve either maintenance or loss of a condition score over the first 100 days of pregnancy before grazing one of five levels of feed on offer between Day 100 and lamb weaning. Across all four experiments, the average difference in ewe liveweight between extreme treatments was: 7.0 kg (range 4.7-8.7 kg) at Day 100 of pregnancy; 11.9 kg (range 4.9-17.8 kg) at lambing; and by weaning was 13.9 kg (range 8.8-22.7 kg). Liveweight at joining and liveweight change during pregnancy and lactation of individual Merino ewes were significantly related to their clean fleece weight, fibre diameter and staple length and thus the second hypothesis was supported. Heavier ewes at joining produced more wool that was longer and broader and this effect was consistent across both sites and years. A 10-kg loss in ewe liveweight between joining and mid pregnancy, mid pregnancy and lambing or during lactation reduced clean fleece weight by 0.4-0.7 kg and fibre diameter by 0.5-1.4 um. At the Victorian site, where ewes were shorn in summer, a loss of 10 kg in liveweight between joining and Day 100 of pregnancy reduced staple strength by 5 N/ktex. As expected the influence of food on offer on changes in ewe liveweight was different between years and sites and between late pregnancy and lactation due to a complex group of pasture and animal factors. Therefore, managing changes in ewe liveweight itself rather than feed on offer will achieve more predictable outcomes. A higher liveweight at joining resulted in a predictable improvement in ewe reproductive rate and liveweight at joining was more important than the liveweight profile leading up to joining. This paper has shown that it is possible to predict the differences in wool production and reproductive rate of flocks of Merino ewes if ewe liveweight records at key times are known.

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“…From a between-flock analysis he estimated that the twinning rose by 5.3% for each additional 4.5 kg of liveweight. Studies of the interaction between nutrition and reproduction were subsequently extended to include ovulation rate (Killeen, 1967;Allison, 1968;Edey, 1968;Gunn et al, 1969;Cumming, 1977;Smeaton et al, 1981;Kelly & Johnstone, 1982;Kelly et al, 1983). Morley et al (1978) in an extensive analysis of data from various published reports concluded that there was a relationship between liveweight and ovulation rate between groups of ewes and in some cases within groups of ewes.…”

Section: Relationship Between Liveweight and Ovulation Ratementioning

confidence: 99%

Nutrient effects on ovulation rate, ovarian function and the secretion of gonadotrophic and metabolic hormones in sheep

Downing

Scaramuzzi²

2019

Proc

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Liveweight, ovulation rate, and wool growth responses of light and heavy ewes to differential feeding

Cited by 12 publications

References 1 publication

Effects of pasture allowance in winter on liveweight, wool growth, and wool characteristics of Romney ewes

Effects of pasture allowance in winter on liveweight, wool growth, and wool characteristics of Romney ewes

The wool production and reproduction of Merino ewes can be predicted from changes in liveweight during pregnancy and lactation

Nutrient effects on ovulation rate, ovarian function and the secretion of gonadotrophic and metabolic hormones in sheep

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