Guidelines to supervising heifer (and twin) calving
Calving difficulties in beef heifers can be a major source of financial loss, with calf death rate up to 10% and in some cases death of the cow. Other costs associated with calving difficulty include labour for supervision and assistance, veterinary fees and the overall reduction of the herd fertility.
As a guide assist at the birth of a calf in the following instances:
Heifers with a single calf
• Maximum of two hours after the ‘waters have broken’, membranes showing or the heifer is actively engaged in labour.
Cows with twin calves
• Maximum for first calf to be born – four hours after the ‘waters have broken’, membranes showing or the cow is actively engaged in labour;
• Maximum after birth of the first calf and before second calf – two hours.
Calf heifers between condition score 2.5 and 3.0 and have them in good physical condition at calving. If the calving of heifers (or cows with twins) is not carefully supervised, difficulties may occur during the birth process with the following consequences:
• The number of still-born calves may increase;
• Calves may fail to thrive;
• Cows may die or be injured;
• Foetal membranes, particularly in twin-bearing cows, may be retained, become infected and so reduce future fertility;
• Veterinary costs are likely to increase.
When a difficult calving occurs, provide assistance in the birth process to improve the chance of cow and calf survival. It is recommended that heifers or cows bearing single calves that need assistance during calving are culled after their calves have been weaned. When calving difficulties (dystocia) are a sufficiently large issue (as judged by the percentage of heifers and/or cows experiencing difficulties), or there is a high percentage of still-born calves, and/or there is considerable time required to assist heifers and cows experiencing difficulties, take action to consider:
• Including ‘calving ease’ as a major part of the enterprise breeding objective when selecting bulls for mating;
• Changing the nutritional management of heifers, particularly leading up to calving.
If excessive time is being allocated to calving management consider the high cost of labour against the benefits of additional calves born.
Mature cows
Mature cows should not need assistance at calving as the cost of labour outweighs the benefits. Aim for cow condition scores between 2.5 and 3.5 and a minimum of 1,500kg green DM/ha in calving paddocks to minimise weight loss in cows and a satisfactory milk production for calves.
What to measure and when
• Twice-daily routine observations, then two-hourly once a cow is actively engaged in labour;
• Take particular note of the number of hours since ‘waters have broken’, membranes showing, or the cow is actively engaged in labour;
• Where calving supervision is excessive, revisit the breeding objectives and birth weight EBV of bulls and cows. Some breeds also provide EBVs for calving ease.
