Background:

Heat stress reduces semen quality in rams.

Objective:

To evaluate the productive and reproductive responses of rams and ram lambs with different rectal temperatures under heat stress conditions.

Methods:

The animals (n = 12, Dorper × Katadhin × Pelibuey crossbreed, aged 235 to 730 days) were assigned to one of three experimental groups: ram lambs with low rectal temperature (RLLRT), ram lambs with high rectal temperature (RLHRT), and Rams.

Results:

Afternoon rectal temperatures were higher (p ≤ 0.05) in the RLHRT group, and there was no difference (p > 0.05) between the Rams and RLHRT groups. Ejaculate volume and sperm concentration were higher (p ≤ 0.05) in the Rams group than in the RLLRT and RLHRT groups. Mass motility and sperm concentration were lower (p ≤ 0.05) in the RLLRT group than in the RLHRT and Rams groups. Average daily weight gain did not differ (p > 0.05) between the RLLRT and RLHRT groups.

Conclusion:

The selection of ram lambs with low rectal temperature under heat stress conditions did not provide any benefit in terms of average daily weight gain or ejaculate traits.

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