Effects of restricted suckling on abnormal behaviour, feed intake and weight gain in dairy calves, and udder health and milk let-down in dairy cows

Sammanfattning: The purpose of this study was to increase our knowledge of how to raise healthy calves with no or few abnormal behaviours and favourable weight gain, along with cows with high milk yield and good udder health. The study investigated the effects of restricted suckling versus artificial milk feeding. The study was carried out on a private dairy farm in Aguascalientes in Mexico. Twenty-two Holstein cow- and calf pairs were alternately allocated to two treatments where calves were artificially milk-fed in open buckets with floating nipple (A) or allowed to suckle the dam restrictively (R). The A-calves were fed whole milk from parlour twice a day, while the R-calves had the possibility to suckle for 30 minutes twice a day two hours after milking. Calves and cows were followed from birth of calf until weaning at eight weeks. Cows were milked three times a day. All calves had free access to hay, concentrate and water. Behavioural observations with 0/1-sampling at one minute intervals were made twice a week during week 1, 3, 5 and 7. All calves were weighed before milk feeding twice a week. R-calves were additionally weighed after suckling to estimate milk intake. California mastitis test was performed and time to milk let-down was noted on the cows once a week. Milk samples were taken from suckled cows and parlour milk. Statistical analysis was done with Analysis of variance with the Mixed effect model, Wilcoxon rank sum test, Chi2-test, F-test and Pearson correlation. Among the A-calves cross-sucking was present in 67% of the animals whereas only 20% of the R-calves performed this behaviour (p<0.05). In the majority (93%) of the cross-sucking recordings the calf was sucking the ear of another calf. The A-calves licked the interior significantly more than the R-calves (p<0.05). The A-calves had significantly more recordings on the behaviours ruminate, eat concentrate (p<0.01) and eat hay (p<0.05) compared to the R-calves. An average A-calf also consumed more than four times as much concentrate as an average R-calf (22 vs 5 kg). There were no differences in average milk intake or live weight gain (LWG), but the individual variation in LWG was significantly higher (p<0.01) in the R-group than in the A-group. Due to a higher fat- and dry matter content, the milk suckled by the R-calves had a higher content of metabolizable energy (ME) than the milk given to the A-calves (3.5 vs 2.9 MJ/kg). Consequently, the two groups ingested approximately the same total amount of ME during the rearing period and therefore they also used almost the same amount of ME per kg LWG (A-calves 40 vs R-calves 42 MJ/kg LWG). There were no differences in either udder health or milk let-down between A- and R-cows. It is concluded that the investigated restrictive suckling system for dairy calves gave less abnormal behaviour, rumination, eating of hay and consumption of concentrate but greater individual variation in milk ME consumption and in LWG compared to artificial milk feeding.