Low Quality Pasture Research Articles

An analysis of growth of different cattle genotypes reared in different environments

SummaryCalves from three breeds, Brahman, Hereford × Shorthorn (HS) and Brahman × HS (BX), were divided equally into two groups, one of which was treated every 3 weeks from birth onwards to control ticks and gastrointestinal helminths, and one of which was untreated. Mortalities, growth rates and levels of resistance to environmental stresses that affected both mortality and growth under grazing conditions were recorded for all animals up to weaning (6 months) and for all males up to 15 months of age. The Brahmans were the most and the HS were the least resistant to environmental stresses, each of which was shown to depress growth in proportion to its magnitude and to contribute to the high mortalities of the HS. All breeds responded positively to parasite control with the greatest response in both survival and growth in the HS breed and the least response in the Brahman breed.Samples of males from the various breed-treatment groups were taken into pens where they were protected from environmental stresses and fed both low-quality pasture hay and high-quality lucerne hay ad libitum. Measurements were made of fasting metabolism, maintenance requirement, voluntary food intake and gain, variables related to the growth potential of each animal. The HS animals had the highest whilst the Brahmans had the lowest values for each variable.However, despite their low growth potential, the Brahmans had the highest growtli rate, and the HS, despite their high growth potential, had the lowest growth rate, when growth was measured in the presence of all environmental stresses. When parasites were controlled, growth rates were highest for the BX, the breed with intermediate growtli potential, and did not differ between the HS and Brahmans. These interactions arose because of the different contributions of resistance to environmental stresses and growth potential to growth rate measured at the different levels of environmental stresses. The relevance of these interactions to breed evaluation and cross-breeding is considered.Growth potential and resistance to environmental stresses were negatively correlated both between and within breeds, though the latter was biased by the effects of compensation. The influence of these relationships on the likely outcome of selection for increased growth rate, both between and within breeds, is discussed.

Influence of preweaning nutrition on growth of Angus calves provided a postweaning nutritional system resulting in discontinuous growth.

Postweaning growth patterns and preweaning milk and forage intake were observed over a 4-yr period for 137 Angus calves allowed either fescue-legume or fescue pastures preweaning. After weaning, calves grazed fescue pasture until spring for a slow growth phase and then fescue, orchard grass, bluegrass and ladino clover pastures for 4 mo. Following this period, the calves were confined and fed shelled corn and a 36% crude protein supplement until they reached 12 mm of fat over the 12th rib. The spring growing period and the finishing period were classified as a rapid growth phase. Calves that were fatter at weaning lost more fat, but gained more in wither height during the slow growth phase, than those that were thinner at weaning. Apparently, fatter calves were more capable of continuous skeletal growth on a low plane of nutrition because they could retrieve fat energy for this growth. In spring, calves that had been relatively fat at weaning held no advantage in fatness, but had larger frames. Therefore, during the rapid growth phase, they were able to fatten more rapidly than those that were thinner at weaning. Also, calves that were more efficient in preweaning growth had more capacity for rapid postweaning growth when restricted to relatively low quality pasture. Preweaning pasture type influenced pattern of postweaning growth. Part of this influence was associated with differences detected at weaning. An additional part was associated with efficiency of forage and milk utilization during the preweaning phase.

Cottonseed meal and molasses as sources of protein and energy for cattle offered low quality hay from pastures of the North Coast of New South Wales

Cottonseed meal and molasses, regarded as sources of protein and energy for cattle, were included with a basal ration of low quality pasture hay and fed to beef cattle in an experiment that contained two periods of 50 d each. The hay was made from a pasture consisting predominantly of Rhodes grass (Chloris gayana). The pasture site was on the North Coast of New South Wales with a subtropical climate and an area where cattle lose liveweight during the winter or cool-dry season. The experiment aimed at determining whether the intake of hay, and liveweight of cattle, could be increased by supplements of either cottonseed meal or molasses or both. The experimental design was based on a response-surface with 12 treatment combinations. Twenty-four Hereford steers, aged about 26 months and having a mean liveweight of 315 � 28 kg were used. They were offered the low quality hay (435 g digestible organic matter (DOM)/kg dry matter (DM); 7.3 g nitrogen (N)/kg DM) in amounts expected to be 15% greater than that eaten. Fixed amounts of the energy supplement (undiluted molasses) were offered in separate containers at 0,0.5, 1.3 and 2.1 kg/d. Cotttonseed meal (930 g organic matter (0M)lkg DM) was added to the hay to raise the N content of the ration from the 7.3 g N/kg DM of the basal ration (A) to 14.1 (B), 19.4 (C) and 25.7 (D) g N/kg DM. Steers on ration C ate 19.3% more hay (P c 0.05) than steers on ration A; steers on rations B and D ate 11.0 and 14.5%, respectively, more hay than steers on ration A ( P < 0.10). Molasses had no significant effect on hay intake, but as did cottonseed meal, it increased steer liveweight. Final liveweight (LW: kg) was a function of the initial liveweight (IW: kg) and of the amount of supplements eaten (kg/d) for both cottonseed meal (CSM) and molasses (Mol). LW = 16.7(+ 11.0) + 5.9(+ 2.0)Mol + 38.3(� 5.6)CSM - 9.2(� 2.0)CSM2 + 0.88(� 0.03)IW; Residual standard deviation � 8.7. N balance, and excretion of N in faeces and urine, were increased (P < 0.05) by cottonseed meal but not by molasses supplements. Liveweight change (LWC: g/d) was a function of N balance (NB: g/d). LWC = - 1 08.3(� 48.0) + 19.7(� 2.1 4)NB; Residual standard deviation � 243. Liveweight change was also a function of the digestible organic matter intake (D0MI:gld) from the total ration. LWC = - 996(� 104) + 0.364(� 0.032)DOMI; Residual standard deviation � 182. The results highlight the limitation to cattle growth imposed by the low N intake from the pasture hay, and a consequent low intake of DOM. They suggest that cottonseed meal is a suitable source of protein for cattle on the North Coast although in districts growing sugar cane economics may favour the use of molasses as an energy source provided that some protein is added to it

The role of protein supplements in nutrition of young grazing cattle and their subsequent productivity

SUMMARYThe effects of supplements of protein meal or sorghum grain given to young cattle for 140 days during their first winter and spring post-weaning, were recorded over 560 days for cattle grazing on low quality pastures in subtropical Australia. The supplements were offered to steers in four treatment groups, replicated three times, at the following rates per head to late spring: (a) mineral mix (M) + cotton-seed hulls, 90g/day (control), (b) M + protein meal, 600 g/day (protein daily), (c) as for (b) but at 2·1 kg/3·5 days (protein twice-weekly), or (d) M + sorghum grain, 560 g/day (sorghum). For the next 130 days, to late summer, only supplement (c) was continued while the remaining three groups were not supplemented. None of the supplements was offered for the final 290 days of the experiment when the steers grazed an improved pasture.At the end of the first spring, the live weight of the steers supplemented daily and twice-weekly with protein was respectively 229 and 216 kg. These were significantly (p < 0·01) heavier than the sorghum-supplemented (174 kg) or control steers (160 kg). At the end of the first summer, the steers given supplements of protein meal twiceweekly, or daily, remained significantly heavier (265, 250 kg respectively) than sorghum-supplemented or control steers (209, 198 kg). By the second summer, the steers previously given protein supplements were still heavier than the steers from the control group (357v. 317 kg, respectively).In steers which were offered the protein supplement during winter and spring, samples of blood taken at the end of spring had lower (P< 0·01) plasma ratios of glycine to branched-chain amino acids (valine, leucine and isoleucine) and a lower ratio of methionine: valine, than in the steers which were not offered the supplement. These ratios were significantly (P< 0·05) correlated with live-weight change over the preceding 140 days. On this basis it was considered that the improved growth of the steers offered the protein supplements was associated with an increased availability of specific essential amino acids, which may have initiated in the steers an increased appetite for pasture D.M.

Patterns of change in mature Angus cow weight and fatness during the year.

Postcalving cow weight and subcutaneous fatness change patterns were described for 80 mature spring-calving Angus cows. The cows grazed either high (regularly clipped fescue-legume) or low (fescue clipped once) quality pastures. Forage consumption was estimated continuously by an internal (acid detergent lignin)-external (Cr2O3) indicator technique. Milk production (calf-suckle technique) was estimated seven times during lactation. Wither height was measured during the fall after the period of intensive measurment. Angus cows grazing high quality pasture lost an average of 36 kg postcalving, whereas those grazing low quality pasture lost an average of 22 kilograms. Minimum weights were observed about April 1, prior to the season of large pasture quality differences in digestibility of consumed forage. Taller cows, when allowed increased nutrient density during midlactation (high versus low quality), responded by increasing (P < .05) fatness at a more rapid rate than less tall cows. For cows grazing high quality pasture, weight change was independent of level of milk production. Cows grazing low quality pasture and giving relatively large amounts of milk maintained less weight and fat during the middle and last part of lactation than did those giving smaller amounts of milk. Shapes of the curves depicting change in weight and fatness were closely related (P < .01) to digestible dry matter intake. Cows apparently consumed forage in such a manner that they became more alike in both weight and fatness as the grazing season progressed.

Response of beef cattle to infused supplements of urea and of urea-molasses when offered a low quality grass hay

Eight Hereford steers, fistulated at the rumen and offered a low quality grass hay (Axonopus affinus comprised 75 per cent of the pasture) were studied in pens for 100 days to evaluate urea and urea-molasses supplements in terms of their effect on hay intake, rumen fermentation and liveweight changes. The hay contained 0.58 per cent nitrogen and had an apparent digestibility of 49.8 per cent. Supplements were made up in a liquid form and infused directly and continuously into the rumen so that on a daily basis 56 g urea with and without 500 g molasses, or 112 g urea with 500 g or 1000 g molasses was delivered. When urea alone was infused, rumen ammonia and plasma urea concentrations were increased (P &lt; 0.05) but the urea had no significant effect on liveweight change, on digestible organic matter intake (DOMI) or on the pattern of rumen fermentation. When infusions of urea and molasses were given, total DOMI was increased (P &lt; 0.08) and the pattern of rumen fermentation changed: total rumen volatile fatty acid (VFA) concentrations were increased (P &lt; 0.05), with an increased (P &lt; 0.05) molar proportion of propionate in one of the treatments. Neither urea nor urea and molasses infusions significantly increased the animal's intake of hay. Liveweight change was related (r= 0.60) to DOMI and it was estimated that steers in the experiment required 41 g DOM kg.-0.75 day-1 for maintenance of liveweight. This level of intake occurred only when supplements containing molasses were given. Overall, the results indicated that little improvement in growth of cattle or of their utilization of low quality pastures could be obtained from a urea supplement. However, there may be potential for molasses as a concentrate supplement for cattle grazing native pastures.

Comparison of Simple vs. Complex Concentrate Mixtures for Dairy Cattle in Puerto Rico: Feeding Lactating Cows Receiving Fair-Quality Forage

A double-reversal experiment with 80-day periods, extending from day 26 to day 265 of lactation, was conducted with 2 groups of 10 cows each. The two treatments consisted of two different concentrate mixtures, one of which had a simple formula consisting of ground shelled corn, soybean-oil meal, fortified molasses, bonemeal, and salt, and was prepared at the Substation, while the other was a complex mixture obtained from a commercial source. Both mixtures contained nearly the same level of crude protein. Concentrate allowances were based upon the Maryland Standards. The remainder of the ration consisted of a moderate amount of sorghum silage, or occasionally green chopped grass, and low-quality pasture. The simple-concentrate mixture proved to be more palatable than the complex mixture. The lactational response obtained with the simple mixture as compared with the complex mixture was significantly (P &lt; 0.01) greater in production of milk uncorrected for fat content, 28.2 vs. 27.1 pounds per day, though not significantly different in production of 4-percent fat-corrected milk nor in production of milk fat. The efficiency of utilization of the simple mixture was significantly, P &lt; 0.05, better for the production of milk uncorrected for fat content, 55.3 vs. 56.8 pounds of concentrates per 100 pounds of milk produced, but not significantly better for the production of 4-percent fat-corrected milk. The cost of concentrates per 100 pounds of milk produced was $2.34 for the simple and $2.67 for the complex mixture. It is concluded that, under conditions of the present experiment, in which forage was limited in quantity and of only fair quality, a simple concentrate mixture formulated to supply digestible energy at a minimum cost is just as adequate nutritionally for lactating cows as a concentrate mixture containing a multitude of different ingredients and supplemented with minerals, vitamins, and antioxidants. It is further concluded that the use of such simple concentrate mixtures prepared at the dairy farm will result in a reduction in feeding costs, provided the operation is large enough to offset the cost of the required machinery. A possible alternative would be the commercial preparation by feed mills of simple concentrate mixtures which could be sold to dairymen at a lower price than the present complex commercial mixtures.