Explain the following in relation to a dairy cow: (i) Length of lactation period (ii) Lactation curve (iii) The relationship between lactation peak and total lactation yield (iv) The management of feeding in a spring-calving dairy herd to ensure the potential lactation peak is achieved. - Leaving Cert Agricultural Science - Question b - 2006

The lactation curve represents the change in milk yield over the entire lactation period. It generally shows a peak in milk production shortly after calving, followed by a gradual decline as the lactation period progresses. The curve can be represented graphically, highlighting key phases such as the ascending, peak, and descending stages of milk production.

The lactation peak is a critical point during the lactation period, usually occurring within the first few weeks post-calving. The total lactation yield can be approximated by multiplying the lactation peak by a factor typically ranging from 200 to 220. This indicates a direct proportionality; a higher peak generally correlates with an increased total yield over the lactation period.

To achieve the potential lactation peak in a spring-calving dairy herd, it's essential to provide a balanced diet that includes concentrates, hay, silage, or grazing. Proper nutritional management during the dry period and early lactation is crucial to support peak milk production, ensuring that cows are fed adequately to promote health and optimal yield.