Abstract
In extensive systems, beef cows should be continuously with their calves to optimise pasture use but this practice can lengthen post‐partum interval (PPI). A study was conducted to determine the influence of suckling frequency on Parda de Montaña cow‐calf performance when cows are fed 70% energy requirements during lactation (outdoor winter conditions simulation). Thirty‐six autumn‐calving cows with similar body condition at calving (2.57) were assigned to three suckling systems [ad libitum (AL), twice (2D) or once daily (1D) for 30 min]. Blood samples were collected twice a week to analyse progesterone concentrations by RIA. Cows lost similar weight until start of mating period (day 52 post‐partum; −0.583, –0.513, –0.520 kg/day in AL, 2D and 1D). Standard milk yield was higher in AL than the rest (8.9, 6.2, 7.0 kg; p < 0.05), which was reflected on greater calf gain (0.895, 0.752, 0.676 kg/day; p < 0.05) and larger cow weight loss within 90 days post‐partum in this treatment (–0.345, –0.188, –0.083 kg/day; p < 0.05). Suckling system did not affect either PPI (69.6, 89.1, 65.5 days) or cows cycling within 90 days post‐partum (55, 46, 58%), which may compromise the target calving interval. In Parda de Montaña breed fed moderately pre‐calving and undernourished during lactation, restricted suckling did not favour ovarian activity resumption, but post‐partum subnutrition delayed about 40 days PPI observed in similar body condition at calving and calf management (Sanz et al., 2003; Anim Reprod Sci 79: 57–69)
Published Version
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