Compensatory Growth Factor

Press, Volume CVII, Issue 31500, 14 October 1967, Page 10

Compensatory Growth Factor

Cattle fed on concentrate* in shelter at Winchmore irrigation research station in the winter of last year made twice the daily weight gains of those fed outdoors on swedes and hay, but by ths time a start was made to slaughter these beasts in March the cattle which had made the poorest winter gains were at least as heavy as the other cattle.

The superintendent of the station, Mr W. R. Lobb, said this week that these trials had shown that summer production of beef could be quite high and the maximum had not been reached at 2.1 beasts an acre. From past experience they were already aware that it was possible to produce adequate feed to sustain high growth rates in cattle over the summer under Irrigation and this had been borne out by the fact that there had always been feed surpluses at the summer stocking rates used in the past. The significant factor now became the number of cattle which could be wintered in a healthy and suitable condition to increase the summer stocking rates. From the evidence of this experiment it was not necessary to achieve high gains in the winter. This coming summer it was planned to stock cattle

on one area at 2.6 beasts to the acre, Mr Lobb said.

In the 1966-67 trial 24 Aberdeen Angus weaner steers were bought in May and grazed on autumn saved pasture and hay until early. July when the wintering experiment began. Equal numbers of cattle then went on to three different treatments. One group was break fed on swedes with hay being fed to appetite on a run-off. A second group was run in a paddock well sheltered with trees and fed concentrates consisting of about 4.51 b of hammer-milled barley meal plus lib of linseed and barley based nuts daily per beast The final group received the same ration as the second group and they also had additional shelter in the form of access to a small shed. All of the cattle were dosed with selenium, sprayed against lice and drenched during the period they were under these wintering treatments.

The three wintering routines were continued for a period of 70 days until September 14, with the exception that in the case of the group on swedes and hay the supply of swedes ran out on August 24 after which they were fed hay alone.

The cattle on the first treatment (swedes and hay) made an average gain over this period of 1.31 b a day (a total gain of 891 b), while those on the second treatment averaged 2.61 b a day (1831 b and those which also had a shed for shelter made a similar average weight gain —2.61 b a day and a total of 1851 b. The groups fed concentrates gained at twice the rate of those wintered outdoors on swedes and hay. After September 14 the cattle were grazed on pasture at two stocking rates—--1.5 and 2.1 to the acre—and were rotationally grazed round three paddocks until slaughter in the late summer. The first group was removed to the abattoir on March 20. In the 181 days that these cattie were at grazing the beasts that had been on swedes and hay in the winter gained 1.91 b a day (a total of 3511 b) where they were stocked at 2.1 to the acre, and I.Blb a day or 3311 b where they were run at 1.5 to the acre. The second group, which had been on concentrates in a sheltered paddock, averaged 1.31 b a day (2361 b at the higher

stocking rate and 1.41 b a day or 2601 b at the lower stocking. rate, and the third group which had the shelter shed gained 1.21 b a day (2271 b and 1.41 b (2471 b respectively.

The over-all result was that the cattle wintered on swedes and hay gained at a greater rate than those on the other winter treatments at both stocking rates. In the case of those wintered on swedes and hay those cattle at the higher stocking rate actually made the greatest gain over the grazing period, but the reverse was the position in all other cases. Over the winter and summer periods the cattle which

had been wintered on swedes and hay'gained on average 4311 b, those on concentrates iq. a sheltered paddock a total of 4291 b, and those on the same diet with a shed as well averaged 4211 b. The annual report of the station aaya that these figures illustrate the excellent recovery of the first group from gains which were the lowest during the winter to the greatest gains during the grazing season. “This compensatory effect produced an animal which was at least as heavy at slaughter as the eattle which had ’been well fed with concentrate supplements.”