Analysis of growth and feed conversion in purebred and crossbred German Merinolandschaf lambs

In this study, ewes of "Merinolandschaf", a breed widespread in southern Germany, were crossed with rams of five meat breed types (Ile de France, Charollais, German black-headed mutton sheep (Deutsches Schwarzkopfiges Fleischschaf), Suffolk, Texel) and Merinolandschaf rams. The resulting lambs (179 individuals) were fattened intensively from 55.3 days and body weight of 20.4 kg until 121.7 days and a weight of 40.9 kg. While fattening, feed intake was recorded and lambs were weighed weekly. Ile de France x Merinolandschaf and Texel x Merinolandschaf seem to be of greatest economic interest for intensive fattening because they showed the best feed conversion rate and energetic feed conversion rate. Only these crosses were significantly superior compared to purebred Merinolandschaf in feed conversion rate and also in daily body weight gain during the fattening period. Except Charollais x Merinolandschaf, all crosses showed at least a tendency of improvement in all three traits compared to Merinolandschaf, although this is not always significant. This underlines the advantage of one-way cross-breeding for efficiently producing lamb meat. The growth was modelled with a linear model and the Gompertz model. The results showed that both models fit the data well, although the average R-2 was slightly higher and the average mean square error was slightly lower for the Gompertz model. In addition, the use of the Gompertz model provided some interesting biological insights concerning the growth of lambs and differences between the crosses, even though the lambs were slaughtered before reaching their mature body weight.