Applied Animal Nutrition-I

NUTRIENT REQUIREMENTS OF THE LACTATING DAIRY GOATS

• Goat milk is also used for human consumption. The nutrient requirement for lactation depends upon the amount and composition of the milk produced.

Milk yield

• Lactation normally last for about ten months, during which time upto 1350 kg of milk may be produced. Peak yield usually occurs at about the sixth week, post partum and is maintained for the next four weeks before declining at the rate of about 2.5 - 3% per week.

Energy requirement

Maintenance

• The fasting metabolism of lactating goats, require 315 kj/kg W^0.75 per day. This is the basic energy requirement.
• It should be increased by about 10% for animals kept indoors, 20% for grazing animals under lowland conditions and 30% for those on the hill, to allow for increased activity. In very dry or mountainous situations these may have to be increased to as much as 100 %.

Milk Production

• The net requirement of energy for milk repoduction is the gross energy of the milk produced. This will depend upon the yield and the energy value (MJ/kg) of the milk.
• The energy value of goats milk is calculated as
• EV_l (MJ/kg) = 0.0376 x Fat (g/kg) + 0.0209 x Protein (g/kg) + 0.948.
• When no data are available, a value of 3.25 MJ/kg or breed values based on the above table may be adopted.

Protein requirement

Maintenance

• The net requirement for nitrogen for maintenance is that required to replace the endogenous urinary loss (EUN) plus part of the metabolic faecal nitrogen loss (MFN) plus loss of nitrogen in hair and scurf (D). The total is termed the basal endogenous nitrogen (BEN) and is of the order of 0.35 g/kg W^0.75/ day, which translates to a metabolisable protein demand of 2.19 g/ kg W^0.75. Metabolisable protein is assumed to be used for maintenance with an efficiency of 1.0.

Lactation

• The average value of crude protein in milk is 32 g/kg and the efficiency of utilisation of metabolisable protein for milk production is 0.68 and the metabolisable protein requirement for milk production is then 32 /0.68 = 47 g /kg.

Requirement for Calcium, Phosphorus and Magnesium.

• Milk may contain 1.3 g Calcium, 0.9 g, Phosphorus and 0.13 g magnesium per kg. Due to lack of information on the minerals requirement for lactating goats, the values similar to cattle are adopted, wherein 0.51,0.55 and 0.17% dietary Calcium, Phosphorus and Magnesium, respectively are recommended.

Nutrient requirement for Indian goats

Ewes

• Milk production from the ewe is directly related to the genetic potential, nu­trition, and number of lambs suckling.
• The genetic potential for milk production varies between and within breeds.
• The lactation curve of sheep is such that peak milk yield is at about 3 to 4 weeks, and 70% of milk production will occur in 8 weeks of lactation.
• The best quality pasture/hay should be saved for feeding during early lactation.

Does

• The average milk yield of a non-descript doe is 60 litres, while it is 100 and 250 litres for Barbari and Jamunapari breeds, respectively, per lactation of 120 days.
• On an average the lactation requirement is 345 g TDN and 45 g DCP per kg of 4% FCM over and above the maintenance requirement.