• No results found


The second maintenance group was fed the same intake as the well fed group and reduced the deficit by 4 7 lb ( 26 percent compensation).

In a second trial in which the winter difference due to feed- ing was 57 lb, compensation (39 percent) only occurred when the animals were subsequently fed to appetite. Slight and moderate restriction of intake resulted in no compensation whatsoever. This suggests that the post-winter feeding level must be sufficiently good to allow a voluntary increase in intake to occur.

Nevertheless, the percentage recovery of the weight lost by winter underfeeding was relatively low, about 40 percent. Over- seas work which Lead to a hope that cattle fed maintenance levels in winter would, through compensatory growth, reach the same slaughter weights as well wintered cattle seem un- obtainable under our conditions of rearing.

An exception appears to occur in a trial reported by Mr G.

Hight of Whatawhata Research Station in which Angus breed- ing cows were fed different amounts of hay and autumn saved pasture for a 120 day winter period. Better fed cows gained slightly and poorer fed cows lost weight gradually throughout this time. The immediate post-calving difference in liveweight was 136 lb. From calving to weaning the rate of liveweight increase in low plane cows was about three times that of high plane cows to reduce the deficit to 18 lb. It appeared that those cows which lost the most weight in winter gained the most after calving.

The usefulness of this example of almost complete com··

pensatory growth is confused by the fact that calf birth weight and weaning weight was reduced and the lower milk produc- tion of underfed cows may have contributed considerably to their recovery.

Trials at Tara Hills

Problems of winter cattle on tussock pastures are every bit as acute as elsewhere. The average duration of winter supple- mentation exceeds 100 days and considerable wintering costs are incurred if young cattle arc to maintain even modest growth rates at this time.

Three trials examining the possibility of exploiting com- pensatory growth have been conducted by Mr G. H. Scales at Tara Hills.


In all trials home bred Galloway x Hereford mixed sex calves, born October and reared on low altitude improved tussock grassland were used. These calves grew at modest growth rates ( 1.5 - 1. 7 lb per day) and entered the trials at 450 -500 lb mean liveweight. The better fed group in each trial was fed good quality lucerne hay to appetite while the poorer group, an amount estimated to maintain bodyweight. In one trial, a third group was fed below maintenance to obtain a large end of winter difference. The calves were then run together on improved tussock until late autumn when they were slaughtered.

The results for the three trials are set out in Table 1.


1967 - 74 Days' Feeding July-September

Initial WintP.r Post· Total Hay Fed Weight Gain Winter Gain lb/Day


Maintenance plus 511 52 334 386 15.3

Maintenance 500 -20 361 341 8.3

Compensation: 3 7.5 percent.

Breakeven cost of hay: 50c bale.

1968 - 112 Days' Feeding July· October

Initial Winter Post- Total Hay Fed Weight Gain Winter Gain lb/Day


Maintenance plus 480 36 306 342 13.9

Maintenance 482 - 14 332 318 10.1

Compen ation: 51.0 percent.

Breakeven cost of hay: 28c bale.

1969 - 103 Days' Feeding June· September

Initial Winter Post- Total Hay Fed Weight Gain Winter Gain lb/Day


Maintenance plus 451 54 192 247 15.3

Maintenance 454 -18 203 185 9.9

Maintenance minus 450 -53 262 209 8.1

Compensation: Maintenance, 15 percent.

Maintenance minus, 65 percent.

Breakcven cost of hay: Maintenance, 90c bale.

Maintenance minus 46c bale.

Wide difTercnces in winter gain ( 50 to I 07 lb) were estab- lished, the maintenance and sub-maintenance groups losing weight. Post-winter growth rates were not outstanding, 1.8, 1.4, 0.8 lb per day rcspecLively for the three years. Neverthe- less compensatory recovery of winter loss of the order of 37 .5, 51.0 and 15 and 65 percent (see Table I ) occurred by the time of slaughter.

In all the trials carc3$ quality was little affected b)" treatment.

A typical comparison of carcass composition and grading from the 1969 trial is given in Table 2.

TABL~ 2 Carcass Data


M .M-

Slaughter weight lb 681 639 659

Carcass yield pcrcrnt 55.9 55.4 55.5

Percent Meat 67.7 67.0 67.7

Percent Fat 6.4 5.9 6.1

Percent Bone 25.9 27.1 26.2

Grade FAQ 2 1 2

CAQ 9 9 7

YAQ 4 l 5






HAY .. __


... ,,' , '


' '



/ M-

/~ .. ' M


'HAY"""' / ' ,,.,<:'/ -~

'.::::_:;/ · '

A 0 0 F A J A 0 0 F 1AI/ 1A1 101 101 1F1 1A1


Insofar as winter de ft.cits were not fully recovered in spring and summer and low plane cattle were slaughtered at lower weights, the practice requires justification on a cost basis.

Relative costs of supplementation have been expressed in terms of the price of hay at which winter feeding costs balance the loss of carcass weight at slaughter. Considerable variations in 'break-even' cost were observed and while restricted feeding may have been. payable in 1967, 1968 and at the M- level in 1969, the economy of the M level in 1969 was doubtful.


Compensatory growth at Tara Hills !has occurred consistently but varied in amount. Weight recoveries under conditions of moderate post-winter feeding were generally good, but fell well short of the desired complete compensation. The influence of post-winter feeding on compensatory growth has not yet been fully explored and it is here that more information is needed to support the practice.

Carcass quality was not affected by restricted winter feeding.


Hight, G. K., 1969: Proc. Ruakura Farmers' Conference Week, p. 54.

Joblin, A. D. H., 1966: Proc. Ruakura Farmers' Conference Week, p. 33.