Productivity of different cow genetic groups in dual-purpose cattle production systems in south-eastern Mexico |
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| Authors: | J G Magana A Tewolde S Anderson J C Segura |
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| Institution: | (1) Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Yucatán, Yucatán, México;(2) Unidad Académica Multidisciplinaria de Agronomía y Ciencias, Universidad Autónoma de Tamaulipas, Tamaulipas, México;(3) Wye College, London University, London, UK |
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| Abstract: | The objective was to evaluate the effect of cow genetic group, nutritional level and their interaction on some economically
important traits of dual-purpose herds managed under field conditions. Nine herds were monitored during a production cycle
in Yucatan, Mexico. Herds were grouped into four nutritional levels (NL) based on the metabolizable energy (ME) apparently
available on pasture, nutritional management, and milk production. Cows were classified into three genetic groups (GG): low
(≤25%), middle (25–75%) and high (≥75%) graded for Bos taurus inheritance. Total milk sold (TMS), days in milk (DIM), TMS adjusted to DIM within each NL (TMSA), body condition score (BCS)
at calving, changes of BCS during lactation (CBCS), calf weaning weight (WW), age at weaning (AW), kg of calf weaned per cow
(KWC) and calf mortality were studied. The statistical model included the fixed effects of NL, GG, month of calving (MC),
parity number (PN) and BCS at calving and GG × NL interaction. The effects of NL, GG, MC, PN and GG × NL were significant
(p < 0.05) for TMS, KWC. As expected, TMS increased with NL from 562.4 ± 106 kg for NL1 to 2366.3 ± 100.1 kg for NL4. KWC was
greatest for NL2 (138.6 kg) followed by NL1 (135 kg); the lowest KWC corresponded to NL4 (96.0 kg) (p < 0.05). TMS values for the middle (1727 ± 94.7 kg) and the high graded GG (1603.5 ± 83.5 kg) were twice those for the low
graded GG cows (828.5 ± 95 kg) (p < 0.05). KWC was also higher for the middle graded group (152.8 kg) than for the low or (104 kg) or the high graded GG (118
kg) (p < 0.05). With better nutrition cows of all GG improved their milk performance but not the calf traits. CBCS was negative
for all GG. The highest BCS lost was for cows in NL1 and NL2 and for cows in the high graded GG (p < 0.05). |
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| Keywords: | Genetic group Nutritional level Dual-purpose system Productive traits Tropics |
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