When it comes to the best method for feeding pre-weaned dairy calves, several factors come into the equation. Among these is determining which method is the most cost effective and which method is best for individual calf growth and health. Increasingly, dairy farmers are turning to automated feeders for pre-weaned dairy calves. Automated feeders:
- decrease labour costs1
- increase the ability to precisely control and measure individual intakes of both liquid and solid feed2
- facilitate the feeding of higher amounts of milk or milk replacer
which leads to higher pre-weaning growth3 , leading to higher eventual milk yield4 and greater lifetime production.
But, what is the best way to wean calves fed higher planes of pre-weaning nutrition via these automated machines? Does using the common method of doing so at a fixed early age such as 6 or 8 weeks is sufficient, even though so doing often results in a growth check at weaning?5
It is important to understand that starter feed intakes are generally reduced when feeding larger amounts of milk replacer6 , which could also lead to reduced growth and greater signs of hunger if weaning at an early age7. One way to avoid this specific pitfall is simply to wean at a later age8. But, this can be quite costly. What to do?
In 'Using automated feeders to wean calves fed large amounts of milk according to their ability to eat solid feed' , de Passillé and Rushen (2016)9 explore the idea of weaning calves fed a higher plane of nutrition based on an individual calf's starter intake (WSI) rather than a fixed age. They compared the results of doing so with weaning at a fixed early age (48 days = EW) and a fixed later age (89 days = LW) and took several factors into account including feed and energy intakes, weight gain and behaviour both during and after weaning. They found that with the help of automated feeders, calves weaned based on their ability to eat solid feed were weaned in a more cost efficient manner than the LW calves and without the growth check of EW calves.
Methods and weaning treatments
In the study, 56 female Holstein calves were fed 4L of colostrum within 6 hours of birth and were placed in individual pens within 24 hours of birth until 5 days of age. While in their individual pens, calves had ad libitum access to waste milk, but were not provided water or starter. At 5 to six 6 of age, calves were transferred to group pens of 5 to 9 individuals, based on 3 different eventual weaning strategies and were fed milk and starter from automated feeders. Calves were allowed 12L/d of pasteurized milk and had ad libitum access to texturized calf starter, grass hay and water, via automated feeders which weighed the intake of each calf at each meal. All calves were weighed once a week via electronic scale.
- One group of calves was weaned early (EW = 14), beginning at 40 days, with their milk allowance gradually being reduced until being fully weaned at day 48.
- Another group was weaned late (LW = 14), receiving their full allotment of 12 L/d up to day 80, with their milk being gradually reduced until being fully weaned at day 89.
- The final group was weaned based on their starter intake amounts (WSI = 28), receiving their full allotment of milk until they had consumed an average of 200 g/d of starter during the previous three days (54.7 days on average), with their milk allotment gradually dwindling to zero when they had consumed an average of 1400 g/d of starter for previous three days (75.8 days on average).
Impact on weight, ADG and behaviour
At week 10, the EW calves were lighter (84.5 kg) than both WSI (90.6 kg) and LW (94.9 kg) calves. By week 13, the weight of the EW calves (108.2 kg) still lagged behind the other two groups, but the gap between the LW calves (115.9 kg) and the WSI calves (115.2 kg) had narrowed.
Likewise, between week 3 and week 13, EW calves had the lowest ADG among the three treatments (1.56 kg p/d), followed by the WSI calves (1.80 kg p/d) and the LW calves (1.85 kg p/d). During the actual weaning period three of the EW calves lost weight. All the WSI and LW calves gained weight, with ADG's during weaning averaging 0.15 kg for the EW calves, 0.96 kg for the WSI calves and 1.21 kg for the LW calves.
Unrewarded visits to the milk feeder, considered to be a sign of hunger10 , were significantly more frequent for the EW calves, both during and just after weaning than for the other two treatments.
Advantages of weaning based on ability to eat solid feed
The WSI calves achieved the same weight at 13 weeks as the LW calves, but were weaned on average 2 weeks earlier than the LW calves. When milk feeding comes at a higher cost compared to feeding starter, weaning based on a calf's ability to eat solid feed seems to provide an economic advantage, comparatively speaking. While early weaning does greatly reduce the amount of milk a calf drinks while increasing their starter intake, this method was less efficient in this study, as it also resulted in a significant growth dip at weaning, leading to lower BW for at least 6 to 8 weeks post-weaning. Using automated feeders to adjust each individual calf's milk allowance based on their ability to consume starter results in an intermediate weaning age, between EW and LW, with the advantage of reduced consumption of milk and increased consumption of starter (like the EW calves), but with the achievement of similar weights as the LW calves.
The ability to adjust the weaning age for each individual calf is just one of the many advantages of automated feeders. They also facilitate the consumption of larger amounts of milk(replacer), which also helps to maintain higher body weights up to and trhough weaning.