The response of early summer calving beef cows and their calves to three forms of supplementary feeding at annual pasture.

Abstract

198 Proc. Aust. Soc. Anim. Prod. Vol. 17 THE RESPONSE OF EARLY SUMMER CALVING BEEF COWS AND THEIR CALVES TO THREE FORMS OF SUPPLEMENTARY FEEDING AT ANNUAL PASTURE D. HAMILTON* and R.C. SEIRER* SUMMARY Three supplementary feeding practices were tested in one year and one in a second on early summer calving cows and their calves. The practices were grain to cows or to calves from summer until the end of winter, or hay to cows and calves during late autumn and winter. Calf carcass weight at weaning was not significantly affected by treatment. These treatments appear to offer little promise of consistent economic benefit. Keywords: beef cows, supplements, calf carcasses INTRODUCTION In regions of annual pasture in north-eastern Victoria some farmers are now calving in early` summer when producing beef calves for slaughter at weaning. With this time of calving there could be merit in using supplementary feed to boost animal performance during the long period of poor quality or scarce pasture that usually follows calving. Therefore, three supplementary feeding practices were tested in one year and one wasrepeated in the next year. One practice was a protein supplement to the cows, because itcould complement the use of body reserves for milk production (0rskov et &l. 1980). MA-TERIALS AND METHODS The main part of the experiment was conducted during 1984 and the remainder in 1985. Only the 1984 circumstances are described in detail, and the performance of the control animals indicates differences in the pasture situation betweenyears. The pasture comprised Tri foli urn subterraneum (cv Woogenellup), Lolium rigi.dum and Hordeum leporinum. Si ngle superphosphate, had been applied at 125 kg/ha every second year for the last IO years; and at double this rate earlier. . On average, the annual rainfall is 580 mm and there is green pasture from late Apriluntil mid November. Rainfalls for the successive months of 1984 were 117,.63, 26, 27, JO, 13, 92, 112, 473 72, IO and 15 mm. Mean maximum and mean minimum daily temperatures for the,month ranged from a high of 29 and s12�C in . February to a low of 12 and l�C in July. Heavy rain in January resulted in some germination, and'later rain kept some plants alive. Plants that survived were stimulated by rain in July, and general germination occurred in August.' The pasture remained green until mid November. The lupins, wheat and pasture respectively, 5.98, I..84 and 1.35% N coarsely cracked, and i.O% of salt mainly Lolium rigidum, -had been made hay used for supplementary feeding, contained, in the DM. The wheat and lupins were and limestanewere added. The hay, comprising 'when seeds were forming. * Rutherglen Research Institute, Dept Agriculture & Rural Affairs, Vic. 3685 Proc. Aust. Soc. Anim. Prod. Vol.. 17 199 The Angus cows were mated to bulls of the same breed for eight weeks each year to begin calving on 20 November. They calved for their second time just before the start of the experiment. At the start of this calving they were about 42 months old, of mean live weight 537241 kg, and of mean condition score 3'.6+0.3 on the 1 to 5 scale of extremely lean to grossly fat proposed by Lowman et al. (1976). The stocking maintained since from three strata one of equivalent rate was 0.8 cows and calves per hectare and it had been the previous autumn. Initial animal allotment was at random of live weights, and any cow failing to calve was replaced with weight. There were three replicates of four treatments, on randomized blocks, with three cows per plot. Supplementary feed was to be provided during winter only if pasture scarcity warranted it. The eventual treatments were: N- no supplementary feeding; C- creep feed with one part lupins and two Par ts whea t freely available to the calves from 16 Marc h to 31 August `P - a daily suppleme nt of 1 kg of lupins and 0.5 kg of wheat per cow/d from 24 January until 37 August ; appe ti te wi thout wastage three times a to 31 Augus I/. from The treatments continued until the calves were weaned and slaughtered at the end of October 1984, and treatments N and C were repeated on the same plots in 1985. The creep feed was provided in covered feeders, located at the regular camping spots. The grain supplement `to the cows was provided in troughs that excluded the calves; During mating, all cows on the same treatment gr.azed together, and were rotated round their plots. The cows were dosed with anthelmintic in late January, April and August. They were also vaccinated in January, February and June against clostridial . diseases, and were treated twice in early winter to control lice. The calves were treated similarly, except ,for no dose of anthelmintic in January. Male ' calves were castrated in January. The animals were weighed monthly. Milk consumption at the N and P treatments was measured at the same time, by the weigh/suck/weigh method, starting-at 0800 h, after the calves had been separated at noon on the previous day and allowed to suck at 2000 h. The calves were slaughtered two days after weaning at the end of October. Chilled carcass weight was estimated as 97% of hot weight with the tail, kidneys and kidney fat included. Thickness of fat cover was recorded on half of each carcass, as the mean of two measurements over the eye muscle between the 10th and 11 th ribs. . Quantity of pasture was measured at representative times of the year, by cutting IO quadrats, each 2,044 cmL, to ground level on each plot. The samples were washed in water, dried at 1 OO'C, and sorted into the fractions representing green pasture and dry. Ati a nalysis of variance was applied to the plot means, using the Genstat compu ter programme (Rothamstead Experimental Station Harpenden ) . 200 FPOC. Aust. Soc. Anim. Prod. Vol. 17 RESULTS The mean quantities of pasture in 1984 and S.E. s were: Date 1 February 9 April 12 July Pasture DM/ha (kg) Green pasture Dry pasture 300249 700 106 500 78 2,5002370 2,100 247 1,700 261 Mean calving dates in 1984 for the treatments N, C, P and H, respectively, were 7 December, 29 November, 8 December and 26 November. The other animal results are shown in Table 1. Table 1. Mean results per animal in 1984 The only significant differences (P<O.O5) in result were for calf growth be,tween treatments N and C for period l/2-4/5 and fo%r milk consumption between. ' , treatments N and P for period 4/g-31/10. In 1985, mean birth date was 29,November and 5 'December for treatments N and C, respectively. In the other results, which are presented in Table 2, carcass weight tendedto be heavier than in 1984, and the response to creep feeding tended to be poorer. The only significant difference in result was for calf growth between the two treatments during period 3. Proc. Aust. Soc. Anim. Prod. Vol. 17 201 DISCUSSION Clearly none o'f the supplementary feeding treatments had a significant effect on calf carcass weight despite substantial amounts of supplement being given. In 1984 this result applied when the sequence of pasture conditions should have resulted in about an average response to treatments C and P and an above average response to treatment H. Results from other centres have also shown an uneconomic response in cows and calves to supplementary feeding. In this respect, Robinson and Cameron (1960) found it uneconomic to increase supplementary feeding above an assumed minimum when producing cattle for slaughter at 88 weeks -old. Also, in present economic circumstances it would have been unprofitable to buy hay to support a heavier cow stocking rate in the results of Bailey et al. (1972), and only the' cost of the oats would have beenreturned in the results of Corah and Bishop (1975) for creep-feeding in the few months before weaning in late summer or autumn. At present the annual variable cost per cow is about $140,`oats and hay cost about $110 and $100 per t, respectively, and'calf live weight returns about $1.10 per kg. Overall, therefore, there seems to be little promise of consistent economic benefit from supplementary feeding only to increase calf growth. REFERENCE S BAILEY, P.J., MORGAN, J.H.L. and BISHOP, A.H. (1972L Aust. Vet. J. 48:304. *CORAH, L.R. and BISHOP, A.H. (1975). Aust. J. Exp. Agric. Anim. Husby15:293. LOWMAN, B.G., SCOTT, N.A. and SOMMERVILLE, S.H.,(1976).. East of Scotlag College of Agriculture. Bulletin No. 6. . 0RSKOV, E.R., HUGHES-JONES, M. and MCDONALD, I. (1980). In 'Recent Advances in Animal Nutrition - The Proceedings of the 1980 Nutrition Conference for Feed Manufacturers, University of Nottingham', p. 85, editor`w. Haresign. (Butterworths.` London). ROBJ[SJSON, T.J. and'CAMERON, N.G. (1960). Aust. J. Agric. Res. C 11-:11OL