González-Anaya A, Ochoa-Cordero MA, Torres-Hernández G, Díaz-Gómez MO, González-Camacho JM

Language: Spanish
References: 25
Page: 31-38
PDF size: 297.66 Kb.

ABSTRACT

Birth and weaning weights, as well as preweaning average daily gain of 55 Rambouillet lambs managed under confined conditions were analyzed, in order to evaluate the influence of number of lambing (1, 2, 3+), type of birth (single, twin), and sex of lamb (male, female) on the above variables. The study was carried out at the Sheep Unit, Facultad de Agronomía, Universidad Autónoma de San Luis Potosí, México. Weaning of lambs was practiced at 12 weeks of age. An analysis of variance was performed for the three variables utilizing for each one a model of fixed effects by means of the PROC GLM of SAS. Overall least-squares means for birth and weaning weights, and average daily gain were 4.7±1.1, 17.9±2.6, and 0.235±0.04 kg, respectively. Birth weight was influenced by number of lambing (p≤0.05) and type of birth (p≤0.01); ewes with 1 and 3+ lambings had heavier lambs (4.9±1.1 and 4.8±1.0 kg, respectively) than those with 2 lambings (4.4±1.1 kg), whereas lambs born as singles were heavier at birth (5.1±0.8 kg) than those born as twins (4.1±0.9 kg). Type of birth influenced both weaning weight and average daily gain (p≤0.01); lambs born as singles had the highest weaning weight and average daily gain (19.6&3177;3.3 and 0.258±0.001 kg) than those born as twins (16.5±3.7 and 0.0203±0.002 kg). There were no interactions between the different variables analyzed. It is concluded that it is necessary to take these factors into consideration in order to utilized them as selection criteria in genetic improvement programs of Rambouillet sheep.

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