Lifetime Daily Yield can be increased by reducing the age at 1st calving, increasing production per lactation and by increasing the number of lactations per cow. Several studies1,2,3 have shown that as a result of increased levels of pre-weaning nutrition, calves will reach the desired body weight to start inseminations at an earlier age and will also reach puberty earlier4. As a result, they can be inseminated earlier and calve at an earlier age. Fertility results of a trial that is part of the Trouw Nutrition LifeStart research programme on the Kempenshof farm are presented in this article5.
The key takeaway from this article
- Holstein dairy calves on an intensive milk feeding schedule reach the desired bodyweight at first insemination at an earlier age.
- This results in a reduction of the age at 1st calving, but may also have an effect on fertility later in life.
Lifetime Daily Yield can be increased by reducing the age at 1st calving
Material and methods
A total of 43 pairs of female Holstein dairy calves were fed colostrum from the same source in equal amounts and blocked by colostrum, parity and season. From day 4 onwards, they had ad libitum access to starter feed, straw and water. All 86 calves were weaned according to a standard protocol at 56 days of age and moved to group housing at 70 days of age. Both groups were fed calf milk replacer at a concentration of 150 g/l. The only difference between the two groups were the different amounts of calf milk replacer fed, with the LifeStart group being fed 8 litres per day compared to 4 litres per day for the controls,
Age at 1st insemination, age at conception and age at 1st calving were recorded for all dairy calves included in the study. First service conception rate in 1st and 2nd lactation were also recorded.
Calves in the LifeStart group reached the desired body weight to be inseminated earlier
Results
Calves in the LifeStart group had an increase of pre-weaning average daily gain of 155 g/day and reached the desired body weight to be inseminated earlier. The age at 1st insemination was reduced by 8 days, the age at conception was significantly reduced by 23 days and the difference was maintained until 1st calving (see table 1).
| Conventional | Intensive | Difference | p-Value | |
| Age at 1st insemination | 399 days | 393 days | 6 | 0.39 |
| Age at conception | 424 days | 408 days | 16 | 0.04 |
| Age at 1st calving | 399 days | 393 days | 6 | 0.39 |
Table 1: Fertility parameters in heifers reared with an intensive feeding schedule compared to heifers reared on a restricted feeding schedule.
There was no difference in first conception rate during the 1st lactation but first conception rate during the 2nd lactation was significantly higher in the group that was fed according to an intensive milk feeding schedule (see table 2).
| Conventional | LifeStart | p-Value | |
| First conception rate during the 1st lactation | 40% | 47% | 0.53 |
| First conception rate during the 2nd lactation | 13% | 41% | 0.03 |
Table 2: First conception rate in animals reared with an intensive feeding schedule compared to heifers reared on a restricted feeding schedule..
Calves growing faster as a result of intensive milk feeding schedules reach their puberty at an earlier age
Discussion and conclusion
Farmers often use body weight development as the key indicator that dairy calves are ready to be inseminated for the first time. The Holstein dairy calves included in this study grew faster as a result of an intensive feeding schedule and calved 15 days earlier. The age at which the oestrus cycle started in the heifers included in this study was not recorded, but work carried out by Bruijni et al suggests that calves growing faster as a result of intensive milk feeding schedules reach their puberty at an earlier age(4). In a study by Heras-Sanchez, 107 g extra ADG in calves as a result of a more intensive feeding schedule resulted in a reduction of the age at 1st insemination from 13.7 months to 12.4 months, with a conception rate at 1st insemination of 73.4% for the group on the intensive schedule vs. 62.0% for the controls.
Intensive feeding calf feeding schedules have an impact later in life, they result in an increase of milk production and a reduction of involuntary culling rates in 1st and 2nd lactation5. The results of this study suggest there may also be an effect on fertility later in life.
References for this article
- Bolt, A. 2019, Meta-analysis to calculate the effect of rearing intensity on functionality of dairy cows, Research paper Mecklenburg Vorpommern Landesforschungsanstalt für Landwirtschaft und Fischerei.
- Bar-Peled et al., 1997. Increased weight gain and effects on production parameters of Holstein heifer calves that were allowed to suckle from birth to six weeks of age. J. Dairy Sci; 80:2523-8.
- Heras Sánchez, J, Effects of feeding a calf milk replacer with elevated levels of fat on average daily gain and fertility, 2020, Proceedings of the 2nd European Calf Conference.
- Bruijni, T.C, Rosadiuk, J.P, Moslemipur, F, Carelli, J.E, Steele, M.A. and D.J. Ambrose, 2019, Carryover effects of pre- and postweaning planes of nutrition on reproductive tract development and estrous cycle characteristics in Holstein heifers. J. Dairy Sci. 102.
- Leal, L, (2019). Lifetime impact of early life planes of nutrition in dairy calves, Proceedings of Smart Calf Rearing Conference, University of Guelph, Canada, November 2-5.
