Farm Table says:
What is the problem?
The sheep industry in Mexico is far from satisfying the internal market of meat and prime cuts. Mexico has a wide range of ecosystems where sheep are raised. These flocks are composed of specialized (reduced focus on wool quality and an emphasis on carcass attributes) and the majority are non-specialized breeds with no genetic improvement programs.
The purpose of this study was to assess genetic and non- genetic factors affecting birth weight, weaning weight and gain from birth to weaning in lambs from different production systems in central Mexico.
What did the research involve?
A year study was undertaken to evaluate the effects of three contrasting management systems:
- year-round grazing (G)
- G plus cereal crop residues and grain supplementation (GS)
- year-round pen feeding (PF) on performance of five genotypes of lambs in central Mexico.
The variables included: type of birth (single/twin), sex (male/female), time of birth (dry/wet) and season of birth (autumn, winter, spring, summer) were studied.
Five hundred and ten lambs of five genotypes were studied:
- Suffolk (S): 131
- Hampshire H: 88
- Wool x hair crosses (Rambouillet x Suffolk x Churraon Pelibuey x Blackbelly: WH): 110
- Suffolk x Hampshire (SH): 89
- Pelibuey (PB): 92 animals
Birth weight (BW), weaning weight (WW), final weight (182 days of age; PW) and pre and post-weaning daily weight gains (DWG) were also studied.
What were the key findings?
- Lambs born in dry season were 19.4% heavier than lambs born in wet season
- Lambs on PF system presented lightest birthweights
- Purebred lambs were heavier than other lambs
- Neonatal mortality was around 8% and there were no differences between breeds
- Weaning weights 27% heavier for lambs on GS system
- DWG was highest in G system post-weaning
In general, wool lambs had better performance than hair lambs. Thus, sheep production systems in the high plateau of central Mexico have an important effect on lamb performance.
It was concluded that the GS system provides the best alternative system for lamb production at the high plateau in central Mexico but at a significantly lower investment relative to PF system. Year-round grazing with cereal crop residues and grain supplementation increased lamb birth and weaning weights and total weight relative to lambs from other production systems. Wool lambs were more suitable for any of the production systems.