Abstract:
Animal Production in Australia Vol. 15 WHEAT RATIONS FOR DROUGHT FEEDING BEEF COWS J.F. GRAHAM*, L.J. CUMMINS* and C. KUTOSI** SUMMARY Pregnant Hereford cows of live weight 462+:5 kg (mea&SE) and condition score 2.7+0.04 were fed one of five drought rations over a period of 169 days commencing 3-6 months pre-calving. One ration was fed at pasture, the others in feedlots. The rations were: 4 kg whole wheat at pasture, 4.6 kg wheat, 3.5 kg wheat, 4 kg wheat + 0.5 kg oaten straw or 7.2 kg oaten hay. These rations were calculated on a daily basis but feeding was two or three times per week. The overall live weight (kg) and condition score (units) changes for cows were -42.8 and 0.2; -104 and 1.0; -137 and -1.3; -87 and -1.1; -106 and -1.6, respectively. Pregnant cows can be fed rations consisting solely of whole wheat; however 3.5 kg was inadequate for a satisfactory liveweight change. No advantage was found by adding straw to the wheat ration, but wheat at pasture gave the best performance. All rations appeared inadequate for optimum performance from lactating cows under the conditions of this experiment. INTRODUCTION At the start of the 1982/83 drought in western Victoria, many doubts were by producers and advisors on the desirability of feeding cattle a expressed ration consisting entirely of wheat, despite the extensive review of this subject by Morris (1968). Little research has been carried out on grain only rations fed to pregnant and lactating cattle (e.g. see Morris and Gartner 1970). The advisory literature available (e.g. Smith 1981) contains differing recommendations on the amount of grain or hay which would be required. To assist local extension and to provide further information on drought feeding pregnant cows, an experiment was conducted at the Pastoral Research Institute, Hamilton. MATERIALS and METHODS Fifty pregnant Hereford cows were allocated to two equal blocks on the basis of expected calving date. Within each block they were then allocated into five groups after stratification on live weight. Two spare cows were run with treatment (i) and were included in the analysis of this treatment (replacing data from cows which failed to rear calves). The five nutritional treatments imposed were:(i) 4.0 kg whole wheat/cow/day fed at pasture = 43 MJ + pasture (ii) 4.6 kg whole wheat/cow/day fed in feedlots = 49 MJ (iii) 3.5 kg whole wheat/cow/day fed in feedlots = 37 MJ (iv) 4.0 kg whole wheat + 0.5 kg oaten straw/cow/day fed in feedlots = 45 MJ (v) 7.2 kg oaten hay/cow/day fed in feedlots = 39 MJ. The percentage crude protein (CP, dry basis) and percentage digestibility (in vitro, DDM% DM) of the wheat, oaten straw and oaten hay was: 10.0 and 86, 4.0 and 44, 8.7 and 48, respectively. The experiment commenced on December 16, 1982 and the cows were gradually introduced to their full rations over a 2-week period. Feeding was daily during the initial 4 weeks of the experiment and then twice weekly (Monday and Thursday). Each block of each nutritional treatment group (i.e. 5 cows) was fed separately. The feedlot treatments were fed in troughs and the pasture treatments fed in a trail on the ground. Ground limestone at 50 g/cow/day was added to all the wheat rations. The cows at pasture were initially on a short, dry, drought affected pasture (stocking rate (SR) of 1.6 cow/ha). Their paddocks were burnt in a fire on February 16 and they were shifted to another paddock which had a cypress windbreak (SR 5.0 cow/ha). Drought breaking rains commenced on March 4. * Pastoral Research Institute, P.O. Box 180, Hamilton, Vic. 3300. ** University of Melbourne, Parkville, Vic. 3052. 365 Animal Production in Australia Vol. 15 Concern about animal health (see Results) led to the adoption of two changes in feeding policy in early March, i.e. all groups were fed thrice weekly (Monday, Wednesday and Friday) and the straw in ration (iv) was fed separately to the grain. On April 7 the ration of treatment (iii) was increased to 4.6 kg wheat/head/day because of their low live weight and condition, and treatment (i) received 1.0 kg hay/head/day because of the increased SR. The experiment was terminated on June 2 due to extremely muddy conditions in the feedlots which were considered unsuitable for young calves. All treatments were turned out together on to pastures which had been saved since March 4. Cows and calves were weighed at weekly intervals directly from feedlots or pasture. The cows were condition scored (Lowman et al. 1976) at fortnightly intervals. Analysis of variance using Duncan's test was applied to the data. RESULTS (i) Animal health: During the trial, six cows were treated for acidosis and two from treatment (iv) subsequently died. Two cows from treatment (iii) had to be withdrawn from the trial, one because acidosis caused it to abort and the other because of recurring illness (acidosis or pregnancy toxaemia). The other two sick cows came from treatments (ii) and (iii). Two cows (treatments (i) and (ii)) required assistance at calving and delivered dead calves. These were considered to be associated with uterine inertia. Four calves from treatment (i) died within 2 days of birth - one was premature, one oversized and no obvious cause of death could be attributed to the other two. Another four calves died between 7 and 9 weeks of age, presumably due to starvation; two were from treatment (ii) and one each from treatments. (iii) and (v). (ii) Cow live weight and condition score changes: Figure 1 and Table 2. These are shown in Months FIG. 1 Live weight (kg) of cows fed either: 4 kg wheat at pasture ----, 4.6 kg wheat - 3.5 kg wheat x-----x 4 kg wheat + 0.5 kg straw o-o, and 7.2 kg oaten hay ;-A. Arrows: 1 = ;ull ration, 2 = start of calving, 3 = when 3.5 kg wheat, and pasture ration increased, 4 = end of calving, 5 = COWS putout to pasture 366 Animal Production in Australia Vol. I5 TABLE 2 Cow live weight (kg) and condition score changes during different periods of the trial, and calf birth weight (kg) and calf growth rates (kg/day) for the different nutritional treatments Over the pre-calving period cows in treatment (iii) lost the most weight while cows in treatment (i) gained slightly. Changes in cow condition score reflected similar trends, with treatments (iii) and (v) losing most condition. During the first month of the experiment, treatments (ii) and (iii) lost significantly (BO.05) more weight than other treatments. Treatment (iii) continued to lose more weight than the others over the remaining period. Cows on treatments (iii) and (v) lost significantly more weight and condition than others during the third month of feeding. (iii) Calf growth: There were no significant effects on sex adjusted birth weight or calf growth rate due to treatment. (iv) Eating times: The length of time taken for the cows to consume their rations was measured on May 16. Cows ate the grain component of the ration at the rate of approximately 1 kg/2.5 min. Those in treatment (iv) ate the straw at a rate of approximately 1 kg/12 min. The cows in treatment (v) took over 24 h to eat their hay. (v) Turning out to pasture: Cattle were admitted directly to pasture on June 2 without problems. Both cows (see Fig. 1) and calves gained weight rapidly. DISCUSSION Despite some problems of adaptation to grain rations experienced during the first 2 months of feeding, it was clear that rations consisting entirely of whole wheat could be satisfactory for drought feeding pregnant beef cows. There was no evidence that these problems of adaptation to grain could be lessened by the addition of small amounts of roughage to the ration. The group fed wheat at pasture had no problems and this was the general experience of local producers who adopted this practice. 367 Animal Production in Australia Vol. 15 Calf birth weights were slightly lower than expected in this environment (Cummins 1979). The pre calving liveweight changes of the five treatments did not influence calf birth weight. Overall calf mortality figures were quite high but it was not possible to attribute these to the nutritional treatments. The deaths in treatment (i) may possibly be attributable to the ingestion of Cupressus macrocarpa foliage of the windbreak (Sloss and Brady 1983). Calf growth rates during early lactation were poor in all treatments and there wereno significant differences. In normal years the early growth rate of autumn born calves from Hereford cattle in this environment is in the order of 0.5-O. 6 kg/day (unpublished data). Substantial liveweight losses observed in treatments (ii), (iii) and (iv) in the first 3 weeks (Fig. 1) are complicated by variations in gut fill but this should not have influenced condition scores which showed very small changes. In late pregnancy all treatments except (iii) had satisfactory liveweight changes. However treatment (v), although showing a satisfactory liveweight change (possibly due to gut fill) lost, along with treatment (iii), substantially more body condition than the other three treatments, the result being that treatments (iii) and (v) calved in condition score 2.1 compared with 2.6 for the other three treatments. However, had post calving nutrition been adequate, the liveweight and condition score losses attributed to the feeding strategies of treatments (iii) and (v) may have been within an acceptable range. In this environment some liveweight loss from December to June would normally be expected (Cummins 1979). The liveweight changes of the cows in treatments (i) and (iv) indicate that the pasture residues available to the cows in treatment (i) were at least equivalent in feeding value to treatment (iv) per day, thus on the type of pasture residues experienced at this Institute in this drought, 3.5 kg at pasture may have been adequate. However, supplementation in the paddock during drought may result in soil degradation and affect subsequent pasture regeneration. In the post calving period only the cows fed wheat + hay at pasture maintained live weight and condition, and we conclude that the other rations were all inadequate. Presumably this was due to both the lactational status and changing environmental conditions (colder winter weather following the autumn break). ACKNOWLEDGMENTS We wish to acknowledge the assistance of Messrs. A. Clark and S. Spiker for technical assistance, Mrs. S. Middleton for statistical analysis and Mr. P. Flinn for chemical analysis. REFERENCES CUMMINS, L.J. (1979). M.V.Sc. Thesis, University of Sydney. LOWMAN, B.G., SCOTT, N.A. and SOMMERVILLE, S.H. (1976). East of Scotland College of Agriculture Bulletin No. 6. MORRIS, J.G. (1968). Proc. Aust. Soc. Anim. Prod. 7:20. MORRIS, J.G. and GARTNER, R.J.W. (1970). Aust. J. Exp. Agric. Anim. Husb. 2:685. SLOSS, V. and BRADY, J.W. (1983). Aust. Vet. J. 60:223. SMITH, G. (1981). Dept. Agric. Vic. AgNote 1431/81. 368