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The objectives of the present experiment were to analyse the reproductive and productive responses to suckling-restriction treatments and flushing in primiparous grazing beef cows. During 3 years, 153 primiparous anoestrus cows were assigned randomly to one of four treatments in a 2 by 2 factorial arrangement of suckling-management treatments and flushing. Suckling-restriction treatments started at 61 ± 10 days postpartum and consisted of applying nose plates to calves for 12 days (i.e. TS treatment) or 5 days of isolation of the calf from the cow followed by applying nose plates to calves for 7 days as calves were reunited with their mothers (i.e. IS treatment). Nutritional treatments (flushing v. control) started at the beginning of the breeding season, immediately after the suckling-restriction treatments were finished (73 ± 10 days postpartum), with cows receiving or not receiving 2 kg/day of whole-rice middling for 22 days. Cow body condition score (BCS) was recorded every 20 days from calving until 120 days postpartum. Duration of postpartum anoestrus (PPA) and probability of cyclicity were estimated by plasma progesterone concentrations analysed in weekly samples. Pregnant cows were determined by ultrasound 42 days after bull introduction (early pregnancy; EP) and 30 days after the end of the breeding season (total pregnancy; TP). BCS at calving and changes in BCS from calving to the day of BCS nadir (ΔBCS) varied among years depending on forage availability and weather conditions. Increased cow BCS at calving decreased PPA (b = –41 days, P < 0.0001) and, in interaction with ΔBCS, increased EP (P < 0.008) and TP (P < 0.003). Calf weights at weaning and average daily gain were not affected by suckling-restriction or flushing treatments. Isolated temporary suckling control reduced PPA by 11 days when compared with temporary suckling control (P < 0.004). Flushing increased EP by 40%, which was also affected by BCS at calving and was greater in cows that gained, than in those that maintained or lost BCS. We conclude that flushing was useful in improving early pregnancy rates of primiparous beef cows with ‘suboptimal’ body condition (lower than 4.5) at calving and grazing native pasture.

Droughts in southern South America affect grazing systems in many ways. They reduce biomass productivity; decrease livestock feed intake, weight and reproductive performance; increase farmers' costs; and reduce farm income. It was hypothesized that simple grazing management variables affect the resilience of grazing systems to droughts at the paddock and farm scales. The effects of grazing management on herbage and animal production were assessed at paddock level, and how technological

Ninety-six Hereford cow-calf pairs grazing Campo grasslands were used in a 2 × 2 factorial design that evaluated stocking rate (high [H] vs low [L]) and creep feeding (CF; yes or no). Creep-fed calves grazing L had a greater average daily gain (1.07 ± 0.03 kg/d) than CF calves grazing H (0.96 ± 0.03 kg/d; P < 0.05), but L − CF (0.78 ± 0.03 kg/d) and H − CF calves (0.73 ± 0.03 kg/d) had similar average daily gains (P > 0.05). Similarly, L + CF calves were heavier at weaning (172 ± 3 kg) than H + CF calves (160 ± 3 kg), but weaning weights between L − CF (144 ± 3 kg) and H − CF (138 ± 3 kg; P > 0.05) did not differ. Creep-fed calves grazed less (39 ± 10%) than non-supplemented calves (58 ± 15%; P < 0.05). Creep feeding had no effect on milk production, body condition and live weight of the dams, so it had no impact on their reproductive performance. We conclude that CF promotes greater live weight gains and weaning weights of Hereford calves grazing Campo grasslands.