Epsilon Archive for Student Projects

Abstract

Cow-calf contact (CCC) systems offer an alternative to artificial calf rearing within the dairy farming practice; it improves calf growth rates and allows cow and calf to express mother-offspring behaviours. However, longer periods of CCC can cause strong behavioural responses in both cow and calf when they are inevitably later separated, and research has yet to agree on optimal management of separation and weaning practices in CCC systems. This study explored a gradual separation system spanning a total of 14 study weeks and containing three successive periods of CCC contact: 24-hour, 12-hour and 0-hour daily contact. The main study aims were to discern whether cow daily lying times were affected by transitioning from 24-hour to 12-hour contact and whether feeding calves additional milk mitigated decreases in calf weight gain often seen after physical separation from the dam. Additionally, the study recorded cow milk yields during the entire study period and investigated cows’ use of the stalls adjacent to the calf confinement area in the mornings before and after initiating 12-hour CCC.
In this study, nine cow-calf pairs were allowed an initial period of 24-hour unrestricted contact lasting 3-12 weeks depending on the birth date of the calf. Study data were only collected for three weeks of the 24-hour contact period, as all calves were not in the experimental pen before this time. Then, a 6.5-week period of half-day contact followed, when calves and cows were separated during nighttime. During the last 4.5 weeks of the study, cows and calves were physically separated but still able to see, hear and smell each other. Calves were introduced to an external milk source from the start of 12-hour contact until week 13 of the study, postponing the point of weaning past the point of physical separation of calves from their dams. Cows’ daily lying time was logged through scan sampling at 10-minute intervals during the week before and the week after the 12-hour contact period commenced. Cows’ use of stalls close to the calf confinement area was recorded for the same period. Calves were regularly weighed to calculate average daily weight gain (ADG) for the different periods. Cow milk yield data covering the entire study period was gathered through parlour software.
Transitioning from a 24-hour to 12-hour contact period did not seem to negatively affect cow lying times – rather, the cows mostly numerically increased lying times during the first week of 12-hour CCC. Cows did not seem to anticipate calf release from confinement, as they did not congregate in the stalls closest to the calf creep before the calves were released in the mornings. The average milk yield delivered in the robot increased numerically during the 12-hour contact, and was at its highest following physical separation. The number of milkings with records of incompletely milked teats decreased numerically with decreasing amount of contact for multiparous cows. Calf weight gain was found not to differ between 24- and 12-hour contact periods, suggesting that 12-h contact in combination with artificial milk feeding was sufficient to maintain high milk intake. Contrary, ADG decreased significantly following physical separation, but the growth rate still exceeded expecta-tions, averaging at 0.9 ± 0.14 kg/day.
These results provide initial indications that gradual reduction of daily contact time may somewhat mitigate the negative impacts of abrupt separation whilst maintaining a high calf growth rate across a variety of calf ages. Temporally dividing separation and weaning and allowing calf access to milk post-separation may serve to alleviate the decrease in weight gain often seen at separation, although further research using more controlled trials is needed to solidify this theory. Cow lying time did not substantially decrease following initiation of 12-hour contact, indicating that this may be a promising strategy to decrease severe separation distress in dams. Similar studies need to be
Abstract
performed on cow lying times when transitioning from 12-hour to 0-hour contact, as this study was unable to evaluate this aspect.