Resumo

CRUZ-COLIN, Lino de la; TORRES-HERNANDEZ, Glafiro; NUNEZ-DOMINGUEZ, Rafael  e  BECERRIL-PEREZ, Carlos M.. Evaluation of productive traits of Hampshire, Dorset and Suffolk lambs in performance testing, at Hidalgo, México. Agrociencia [online]. 2006, vol.40, n.1, pp.59-69. ISSN 2521-9766.

Data on 326 Hampshire, 97 Dorset and 88 Suffolk lambs in four performance tests were used to evaluate final weight (FW), average daily weight gain (ADG) and feed conversion (FC) and, at the end of each test, loin muscle backfat thickness (LMFT), loin muscle depth area (LMDA) and loin muscle area (LMA). The tests lasted 75 d; the first 15 d was an adaptation phase. Lambs were penned individually and kept under the same feed and management system. LMFT, LMDA, AND LMA were measured between the 11th and 12th ribs with ultrasound procedures. Statistical analysis was performed using the GLM procedure of SAS. The model included the fixed effect of year (2000-2003), month of birth (period 1 and 2), breed (Hampshire, Dorset, Suffolk) production unit (16), type of birth (single, multiple), age of ewe (1-3+ years), as well as first-order significant interactions and body weight at the start of the test (nested within breed) as a covariable. There were differences (p≤0.05) among breeds for FW, ADG, FC, LMFT and LMA. Suffolk lambs had a FW of 66.0±1.4 kg, followed by Hampshire (64.6±0.8 kg) and Dorset (59.2±0.8 kg) lambs. ADG was higher for Hampshire (0.45±0.01 kg) than for Suffolk (0.42±0.02 kg) and Dorset (0.37±0.01) lambs. Hampshire lambs had better FC (3.9±0.1) than Dorset (4.6±0.1) and Suffolk (5.8±0.2) lambs. Suffolk lambs had a higher LMFT (8.3±0.5 mm) than Dorset (5.2±0.3 mm) and Hampshire (5.0±0.3 mm) lambs. For LMA, averages were 15.1±1.0, 14.4±0.6, and 13.3±0.6 cm2, for Suffolk, Hampshire and Dorset lambs. Differences (p≤0.05) were found for ADG and FC due to month of birth; lambs born in period 2 had better ADG and FC (0.43±0.01 kg and 4.6±0.1) than those born in period 1 (0.40±0.01 kg and 4.9±0.1). Age of ewe affected only LMFT (p≤0.05); lambs born from one-year-old ewes had the lowest average (5.7±0.2 mm) compared with lambs born of two and three-year-old ewes (6.4±0.1 mm). Hampshire lambs had the best averages for the variables analyzed.

Palavras-chave : Loin muscle area; loin muscle backfat thickness; lambs.

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