Demonstration of diet to influence lamb sex-ratio
| Project start date: | 12 February 2016 |
| Project end date: | 24 September 2019 |
| Project status: | Completed |
| Livestock species: | Sheep, Lamb |
| Relevant regions: | NSW |
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Summary
Previous research at the Wagga Wagga Agricultural Institute conducted by the NSW Department of Primary Industries (DPI) indicated that the proportion of female lambs was approximately 14% higher when ewes were fed oats and cottonseed meal (CSM) compared with silage around joining.
A Producer Demonstration Site (PDS) was formed to investigate opportunities to validate at the farm level results from this previous research, which indicated potential economic benefits to sheep producers through manipulation of ewe diets to influence the ratio of male to female lambs.
The proportion of female lambs was not consistently higher when ewes were fed grain in addition to pasture compared with pasture only, however, basal diet significantly influenced the sex ratios observed. Further research is required to more accurately predict ewe response to grain feeding.
Objectives
The objective of this project was to determine whether results achieved during research trials (achieving greater than 10% more male lambs than females by feeding ewes omega 3 fatty acids at joining), could be replicated in a range of commercial sheep enterprises (years one to three).
Progress
The number of fetuses per ewe at pregnancy scanning was variable but higher when ewes were fed grain in addition to pasture (1.32 ± 0.01 fetuses/ewe scanned) compared with pasture only or pasture supplemented with silage (1.25 ± 0.01 fetuses/ewe scanned).
The proportion of female lambs at marking was 1.5% higher when ewes were fed grain in addition to pasture (53.3%) compared with pasture only (51.8%) although this result was not statistically significant.
In Year one of the study, there was evidence that the fatty acid profile of ewe plasma at joining was related to the sex ratio of lambs at marking.
