LAMB FATTENING

New Zealand Herald, Volume LXXIV, Issue 22860, 15 October 1937, Page 5

LAMB FATTENING

ALTERNATING PERIODS GROWTH AND CONSOLIDATION IMPORTANCE IN FEEDING

BY H.B.T.

| Throughout all forms of life, under natural conditions, periods of growth alternate with periods of consolidation. The length of these periods vary in different forms of vegetable life, and in different animal species. Among herbivorous animals such as cattle and sheep, the periods of growth and consolidation correspond fairly closely with those of their natural food. This is important, for during its growing period every species requires a high proportion of proteins, which are embodied in nitrogenous substances. In the following approximately equal period of consolidation, however, the demand is for a greater proportion of carbohydrates. If these periods did not coincide among animals and their fodders, they would experience the disadvantage of trying to make growth on fattening feed, high in carbohydrates, and of attempting to consolidate that growth (that is, put on condition) on a diet high in proteins and low in carbohydrates.

Failure ol Early Lambs The importance of a knowledge of these factors will be apparent to any farmer who, for instance, breeds lambs for fattening. If he lambs his ewes too early they arrive at a time when the protein content of the pasture is low, because the grass has not commenced to make its rnpid spring growth. "Unless both ewes and lambs are then fed a protein-rich diet, such as lucerne hay, green clover or lucerne, or aro given some supplementary food rich in protein, the abnormally early lambs will fail to make rapid growth. They will be caught and passed in size and condition by lambs which arrive later, when the pastures are making their early spring growth. Similarly, lambs which are dropped too late miss a large part of the growing season when there is abundant protein, and are compelled to try to make continued growth on a fattening, and not a growing diet. • I have heard many sheep farmers, in commenting on the fact that both very early and very late lambs fad to make good growth, ascribe this to excessive .cold which retards the growth of + *ie early lambs, and excessive heat which the late-dropped lambs have to put up with. My experience has been that temperature has very little to do with growth rate. The difference is entirely in the protein content of the grass and in the ewe's milk. If these very early, or very late lambs are given supplementary feed (such as meatmeal or dried blood) which is very high in proteins, they will make equally rapid and healthy growth as will lambs dropped when the protein-rich spring grass is coming/away.

The Optimum Lambing Time It will be realised, therefore, that unless a sheep farmer is prepared to give his lambs a nitrogen-rich food to supplement his grass, there is an optimum time when lambing should commence. This will vary in different districts as well as on country having an easterly or north-easterly aspect in the same districts. '» The reason for the early growth and high protein content of pastures lying to the rising sun is somewhat obscure, but it is suggested that sunlight passing through air, actively precipitates nitrogen to the soil and that this is used by the bacteria. As the early morning sun passes through a considerably wider belt of air than it does later in the day, it is conceivable that this would increase the rate of nitrogen precipitation. It Will have been noticed that such faces lying to the rising sun have -i high proportion of clovers in the* sward. This would appear to contradict the theory that this sod is highly impregnated with nitrogen, for this element encourages the growth of grasses rather than of clovers. However, it must be remembered that all the legumes are nitrogen gatherers and actually harbour nitrogen-fixing bacteria in nodules on their roots. Their broad leaves also appear to be specially adapted for making use of every ray of early morning sunlight. Nature has thoughtfully provided that the first pasture growth to come away in spring is the clover family, high in both proteins and minerals — the very ingredients most needed bv young utock to produce healthy, rapid growth. He is a wise farmer who times his ewes' lambing to coincide with the first growth of clover. The period of growth following the birth of a lamb, lasts for approximately three mpnths. This corresponds closely with the period of rapid growth in pastures in spring. Then, as the mature grasses and clovers commence to ripen, their protein value falls and carbohydrate rises. It is then that the first rapid growth shows up, and fattening commences.