Influence of kid rearing systems on milk yield, kid growth and cost of Florida dairy goats

The aim of this work was to study the effect of two different kid-rearing systems, natural or artificial, on milk yield, composition, hygiene-sanitary quality, kid growth and cost in Florida dairy goats. Two groups of animals were created, one with goats under natural suckling and the other under artificial rearing. In the suckling group, the kids were suckled up to 5 weeks of age, and had free access to goat milk 24 h a day. Dams in the milking group were separated from their kids at 48 h post-partum; then, kids were reared artificially, and the dams were milked twice daily. The number of goats used in each rearing system was 20 (all giving birth to twins). Each week, from the 2nd to the 5th post-partum, the volume of milk produced was measured, and individual samples were taken. The chemical composition, the bacteriology, and the somatic cell count of the milk were analysed. The kids, of both sexes, were assigned to two groups, natural suckling (NS, n = 40) and ad libitum artificial rearing (AR, n = 40), and birth weight and weight every week from the second to the fourth week of life were recorded. During the 5 weeks of lactation the total milk yield per goat was higher for the NS group (93.6 L vs. 71.2 L), although the total amount of marketable milk was greater for the AR group, with a difference of some 39 L. There was a significant effect of the rearing system for the contents of fat, protein, and non-fat dry extract, the goats in artificial rearing presenting the highest values. No effect of the rearing system on the somatic cell count was observed. No significant effect was observed either for the feeding system or the sex on the live weight of the kids at 28 days and the postnatal growth rate from birth to 28 days. Natural suckling costs were slightly lower than artificial rearing (€14.5/kid vs. €15.4/kid, respectively), but if the additional per-goat milk production in the NS group (22.4 L) is taken into account, the extra income per naturally suckled kid is €5.18.