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 illustrates the change in milk yield over the lactation period. It is generally characterized by an initial increase in milk production after calving, reaching a peak around 6 to 8 weeks post-calving, followed by a gradual decline towards the end of the lactation period.

There is a direct relationship between lactation peak and total lactation yield. Typically, the total lactation yield can be estimated using the formula: $ext{Total Lactation Yield} = ext{Lactation Peak} imes ext{(200 to 220)}$ This means that a higher lactation peak results in a significantly higher total yield, emphasizing the importance of achieving a strong peak.

To achieve the potential lactation peak in a spring-calving dairy herd, it's essential to manage the feeding strategy effectively. Providing a balanced diet that includes concentrates, hay, silage, or grazing ensures that the cows receive adequate nutrition. This nutritional management supports optimal milk production and helps the cow to reach her peak yield during the critical early weeks of lactation.