Feed Intake with Adjustments of the Maintenance Energy Requirement - Lactating Goats
Feed intake prediction equations were developed from data with goats in confinement and without appreciable impact of factors such as acclimatization or grazing (Luo et al., 2004). Similarly, it was not possible to address gender. However, the physiological premise on which the equations were based suggests that they could be appropriately used with maintenance energy requirements adjusted for various factors. Therefore, it was felt desirable to include as an option a feed intake calculator that includes adjustments. But, since the efficiency of energy use for gestation is markedly different than for maintenance, feed intake would not necessarily be predicted accurately for a goat in the last 56 days of gestation. Also, because the method of intake prediction involved assumed efficiencies of energy metabolism for different functions and maintenance energy requirements, an adjustment for body condition score as influenced by previous nutritional plane, which may influence both factors, was not included.
We will use a 50-kg dairy goat with 0 average daily gain (ADG) producing 3 kg of milk with 3.5% fat and consuming a diet with a ME concentration of 11 MJ/kg dry matter. This results in a predicted dry matter (DM) intake of 2.08 kg.
However, if the maintenance energy requirement is adjusted for a grazing factor of 1.13 (grazing plus walking time = 7 hours; distance traveled = 4 km; terrain score = 2), then predicted DM intake is 2.19 kg.
If the maintenance energy requirement is also modified for an acclimatization adjustment of 0.16 MJ (average daily temperature for the previous 30 days = 18 degrees C; mid-point temperature of the thermoneutral zone = 20 degrees C), predicted DM intake becomes 2.21 kg.
The sources used in this calculation method are:
Luo, J., A. L. Goetsch, I. V. Nsahlai, J. E. Moore, M. L. Galyean, Z. B. Johnson, T. Sahlu, C. L. Ferrell, and F. N. Owens. 2004. Voluntary feed intake by lactating, Angora, growing and mature goats. Small Ruminant Research 53:357-378.
Nsahlai, I. V., A. L. Goetsch, J. Luo, Z. B. Johnson, J. E. Moore, T. Sahlu, C. L. Ferrell, M. L. Galyean, and F. N. Owens. 2004. Metabolizable energy requirements of lactating goats. Small Ruminant Research 53:253-273
Sahlu, T., A. L. Goetsch, J. Luo, I. V. Nsahlai, J. E. Moore, M. L. Galyean, F. N. Owens, C. L. Ferrell, and Z. B. Johnson. 2004. Nutrient requirements of goats: developed equations, other considerations and future research to improve them. Small Ruminant Research 53:191-219.