L'alimentation uniquement a base d'ensilage donne des resultats equivalents aux rations a base de fourrage grossier seul, mais moindre que des rations a base de concentres, tant du point de vue zootechnique que du point de vue des carcasses

La vitesse de croissance est modifiee mais la qualite des carcasses et de la viande n'est pas alteree apres velage

The effect of diethylstilbestrol (DES) on the composition of tissue gain of Hereford steers was studied in a complete slaughter balance trial. Eight steers were slaughtered initially (IS) and, after 177 days on feed, eight control steers (C) and seven steers that had been fed 20 mg DES daily (DES) were slaughtered. Initial full body weight averaged 224.8 kg, and final full body weight averaged 403.0 kg for the C steers and 433.6 kg for the DES steers. Final empty body weight averaged 346.6 kg for the C steers and 368.0 kg for the DES steers. DES improved live weight gain by 17% and conversion of feed dry matter to live weight by 12%. Recovery of wet weight during slaughter averaged 99.6%. DES steers had larger rib cut weights and greater proportions of separable lean and bone plus connective tissue in the rib cuts than C steers, an ribeye area tended to be larger in DES steers. DES caused a small shift in relative body composition toward more protein, moisture and ash. Tissue gain in DES steers consisted of 28.3% more protein, 26.0% more moisture, 73.2% more ash, 1.5% less fat and 109.1% more residual (dry matter not accounted for by N x 6.25, ether extract and ash) than did tissue gain in C steers. Energy gain per unit of energy intake over the feeding period was not affected by DES treatment, but DES improved protein gain per unit of protein intake and per unit of energy intake by approximately 20% within the total empty body and by about 25% within the carcass fraction. Results confirm indirect estimates in the literature indicating that DES increases skeletal growth and lean tissue deposition in feedlot steers.

Alfalfa juice protein-lipid products were evaluated in digestion and growth experiments as sources of protein and energy for lambs. In the first experiment, juice was pressed from fresh alfalfa, emulsified with safflower oil and (A) dehydrated, (B) treated with formaldehyde and then dehydrated or (C) blended with solubles that remain after protein is removed from alfalfa juice and then dehydrated. The three products averaged 47% crude protein and 26% ether extract on a dry matter basis. In vivo digestibility of crude protein was 67, 26 and 65% for products A, B and C, respectively, and in vivo digestibility of ether extract was 63, 54 and 56%. Sixteen lambs were fed three corn-based diets containing 20% of the proteinlipid products (diets A, B and C) and a control diet (D) containing alfalfa meal and soybean meal during a 40-day study. Average daily gain for lambs on diets A, B, C and D was 324, 229, 332 and 288 g, respectively and average daily dry feed intake was 1,347, 1,180, 1,260 and 1,297 grams. Protein digestibility and gain were lower (P

Journal Article Effect of Ruminal Ammonia Concentration on Nitrogen Utilization by Steers Get access L. L. Slyter, L. L. Slyter 4U.S. Department of Agriculture, Beltsville, MD 20705 Search for other works by this author on: Oxford Academic PubMed Google Scholar L. D. Satter, L. D. Satter 4U.S. Department of Agriculture, Beltsville, MD 20705 Search for other works by this author on: Oxford Academic PubMed Google Scholar D. A. Dinius D. A. Dinius 4U.S. Department of Agriculture, Beltsville, MD 20705 Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Animal Science, Volume 48, Issue 4, April 1979, Pages 906–912, https://doi.org/10.2527/jas1979.484906x Published: 01 April 1979

Research was conducted to examine rate of digestion and ruminoreticulum parameters of beef steers fed the following ground (2.5 cm screen) roughages: (1) orchardgrass hay, (2) barley straw, (3) corn stover or (4) cottonseed hulls (not ground), plus 1 kg daily of a protein-mineral supplement per steer. In the first trial, a Latin square design was used with four Angus steers (avg wt, 242 kg) fed each roughage at 2% of body weight daily. Orchardgrass hay had the highest digestibilities of dry matter (60.1%), crude protein (54.1%) and cell wall (64.2%), whereas corn stover and cottonseed hulls had the lowest digestibilities of dry matter (48.9, 46.0%) and cell wall (52.3, 45.6%). In a second trial, four rumen cannulated Angus steers (avg wt, 238 kg) were fed the same roughages ad libitum in a Latin square design. Steers consumed 26, 49 and 71% more cottonseed hulls than orchardgrass hay, barley straw or corn stover, respectively. Steers fed cottonseed hulls had a greater amount of digesta dry matter per 100 kg empty body weight and a higher digesta density which contributed to allowing them to consume more cottonseed hulls than the other roughages. An in situ dacron bag technique was used to evaluate potential digestibility and rate of digestion for the roughages. Orchardgrass hay had the highest potential (percentage loss after 72 hr) dry matter (68.5%) and cell wall (70.3%) digestibilities while cottonseed hulls had the lowest potential dry matter (31.0%) and cell wall (33.1%) digestibilities.

Barley straw was treated with sodium hydroxide .(4 kg NaOH/100 kg straw) by ensiling chopped straw mixed with NaOH solution or by pelleting ground straw mixed with NaOH solution. Treated straw was compared with chopped straw, with chopped straw mixed with water and ensiled, and with ground pelleted straw. Each straw preparation was fed ad libitum to rumen fistulated Angus steers and was fed at restricted levels (3.6 kg straw dry matter/day) to nonfistulated steers during three 4-week periods. A supplement of 90 parts soybean meal and 10 parts minerals and vitamins was fed at 1 kg/day. Apparent in vivo digestibilities of dry matter, organic matter and neutral-detergent fiber in the untreated, chopped straw preparations were 55, 57 and 62%, respectively. Digestibility of these components was reduced by 8 to 10 units (P<.01) by grinding and pelleting straw. Alkali treatment of either the chopped or pelleted straw increased digestibility of these components by 10 units compared to the respective nonalkali treated straw. Potential digestibility of straw dry matter in the rumen, estimated by using dacron bags over 72 hr, was increased by alkali treatment from 49 to 84% (P<.01) in chopped straw preparations and from 59 to 73% (P<.05) in pelleted straw preparations. However, the rate constant, a measure of the rapidity of digestion of the potentially digestible fraction, was within the range of .044 to .052 for all straw preparations. The similarity among digestion rate constants indicates that the percentage of potentially digestible dry matter that was digested at a given time was the same among treatments even though potentially digestible dry matter was increased by alkali treatment. Results of in vitro fermentations were similar to those with dacron bags. Intake of straw digestible organic matter was increased from 2 to 3 kg/day (P<.05) by grinding and pelleting or by alkali treatment of straw. The total volume of rumen ingesta did not vary among diets; however, the rumen retention time of undigested particles was reduced 9 hr by either grinding and pelleting or by alkali treatment and 10 hr by a combination of both treatments compared to chopped straw. We concluded that intake of these diets was limited primarily by ruminoreticular fill.

Beef cattle can be finished at high-Good to low-Choice grades on harvested high-quality forage, but the feeding period generally is longer and the dressing percentage lower than when concentrates are fed. Finely chopped or ground high-quality forage is necessary for maximum intake and hence maximum rate of gain by cattle finished on forage. Cattle appear to gain faster on hay than on silage diets, but this comparison is tenuous because higher quality forages have been used more commonly with hay studies than with silage studies. Supplementing silage diets with hay or supplementing either silage or hay diets with concentrates increased rate of gain. Hormonal implants and dietary monensin greatly increased rates of gain of cattle finished on forage diets. Gain in response to dietary lipid supplementation in forage diets has been inconsistent.

SUMMARY Three feeding experiments were conducted with finishing Iambs to determine whether formaldehyde treatment of dehydrated alfalfa meal, intended as a protein protectant, would affect the iambs' performance. The treated alfalfa meals comprised 25% of the lamb's diets, the rest of which was 62% corn meal, 10% molasses, 2% minerals and vitamins and 1% urea. In two experiments, rate of gain, feed consumption and feed efficiency were not affected (P>.05) by formaldehyde levels of .33 to 2% of meal weight. In a third experiment, 1% formaldehyde treatment increased feed con- sumption, but rate of gain was unaffected and feed efficiency was reduced. A substantial part of the total formaldehyde recoverable from the treated meals by phosphoric acid hydrolysis and distillation was also recoverable by merely slurrying the meal in water and incubating for 18 hr at 37 C or for 30 rain at room temperature. Moreover, acid-detergent insoluble nitrogen, a measure of heat damage in hays and silages, was increased by formaldehyde treatment. The chemical similarities of the nonenzymatic browning reaction, to which heat damage in forage is largely attributed, and the reaction of formaldehyde with protein is briefly discussed.

Finishing beef cattle on forage diets was investigated in three factorial experiments involving a total of 154 steers. In the first experiment, rate of gain differed little between steers fed a diet of 94% ground alfalfa hay or 94% dehydrated alfalfa meal, or between steers fed the diets in ground or pelleted form. Steers fed 30 ppm dietary monensin3 consumed an equal quantity of feed daily but gained 25% faster (1.15 vs .92 kg, P

Animal performance, carcass characteristics and meat palatability of steers fed a concentrate diet for short periods were evaluated. Forty steers (424 kg) from a forage study were assigned to four groups and three of the groups were switched to an 85% concentrate diet during a 5-day interval and then fed this diet ad libitum for 3, 6 or 9 weeks. Average number of days the steers were on experiment, including the dietary adjustment period, was 51.0, 27.5,48.0 and 68.5 for treatments of 0, 3, 6 and 9 weeks of concentrate, respectively. Daily live weight gain was not different (P>.05) among treatments; however, the experimental periods were relatively short. Dressing percentage increased as the period of feeding concentrate increased. Calculated daily carcass gain was higher for steers fed concentrate than for those fed hay (.67 vs .36 kg, P<.05). Length of the period that concentrate was fed did not affect lean color or texture but did increase (P<.05) the amount of marbling in the longissimus muscle at the 12th rib. Differences in marbling were reflected by differences in USDA quality grade. Length of the period that concentrate was fed had little influence on cooking properties of the meat or palatability as judged by a trained taste panel. Extractable lipid from the longissimus muscle increased, the relative percentage of stearic acid decreased and that of oleic acid increased as the period of feeding concentrate increased.

Finishing beef cattle on forage diets was investigated in two experiments involving a total of 114 steers. In experiment 1, type of forage had significant effects on ratings for amount of marbling, USDA quality grade, and fat color. Steers fed alfalfa hay vs dehydrated alfalfa meal had significantly more marbling and higher USDA quality grades. The form of the diet (ground or pelleted) significantly affected chilled carcass weight and marbling score. Form of diet did not significantly affect fatness or marbling traits. The addition of a formaldehyde-treated protein-lipid feedstuff to the diet had few practical or significant effects on carcass traits or palatability (experiment 2). Steers fed ground alfalfa and orchardgrass hay produced meat that was tender, juicy and intense in flavor; whereas, cattle fed orchardgrass pasture produced meat that was less tender (panel and shear force), less juicy, and had a moderately abundant amount of panel dectectable connective tissue.

Cattle responses to the chemical feed intake stimulant elfazepam3 (7-chloro-l-[2-(ethylsul-fonyl)ethyl] -5-(2-fluorophenyl)-l,3-dihydro-2H-l,4-benzodiazepin-2-one) were investigated in three experiments. In experiment 1, 24 beef steers were fed for 117 days a 90% ground orchard-grass hay diet to which 0, 5,1.0or2.0ppm of elfasepam was added. Animal responses to the three levels of elfazepam were similar; average daily gain, dry feed intake and feed/gain ratio were .41, 8.2 and 20.7 kg, respectively, for the control steers and .52, 8.8 and 17.3 kg for the treated steers. In experiment 2, eight cattle with rumen fistulas were fed the orchardgrass hay diet containing 0 and 1.0 ppm elfazepam for 28-day periods in a simple change-over design. There were no differences (P>.10) in daily dry feed intake (9.7 vs 10.1 kg), in weight of ruminal contents (12.5 vs 12.8% of body weight) or in total volatile fatty acid concentration in ruminal fluid (79.0 vs 85.4 μM/ml) between the control and treated cattle, respectively. In experiment 3, 32 steers were fed for 98 days a medium-quality ground alfalfa-grass hay diet. The chemical treatments tested were 1.0 ppm elfazepam and 30 ppm monensin sodium3 added to the feed and Synovex S3 implantation in a completely balanced factorial design. Gain was increased by elfazepam and the implant (P<.05), feed intake was decreased by monensin (P<.01) and increased by elfazepam (P<.05), and feed/gain ratio was improved by the implant (P<.001). At slaughter the steers weighed 433 kilograms. Steers fed monensin had a lower (P<.01) dressing percentage and steers implanted had a lower (P<.05) carcass grade than those not so treated.

Two beef cattle feedlot experiments were conducted to determine the amount of certain agricultural chemicals that are likely to be found in both fresh and stored feedlot manure and to investigate fly control in this manure. In experiment 1, diethylstilbestrol (DES), chlortetracycline (CTC), and ronnel were used as feed additives. Fresh manure, stored manure, runoff water, manure weathered on pasture, and soil from pasture fertilized with manure were analyzed for these additives. Stirofos was added to fresh manure as a larvicide for fly control. In experiment 2, the residue aspects of DES and CTC were repeated. In this experiment, stirofos instead of ronnel was fed with DES and CTC. Sixty-eight percent of the DES fed to cattle appeared in fresh manure and 52% in manure stored for 12 weeks. Comparable percentage values were 17 and 11% for CTC and 13 and 3% for ronnel; somewhat less DES and CTC were found when a concentrate diet was fed. Detectable amounts of DES, ACT, and ronnel were not found in runoff water, weathered manure, or soil. Adding an emulsifiable concentrate formulation of stirofos directly to manure at a rate of approximately 45 ppm of wet manure completely controlled the larvae of house fly (Musca domestica L.) whereas feeding stirofos at a rate of 1.5 mg per kg of body weight daily reduced larval counts 82% in manure from forage-fed heifers and 63% in manure from concentrate-fed heifers. Stirofos was not detected in runoff water, weathered waste, or soil.

Research was conducted to test nonprotein nitrogen (NPN)-protein supplements in a mineral mixture for growing steers fed crop residues free choice. Three trials involving 184 steers were conducted. Animal performance and ruminal parameters were measured. Results indicate: Supplements containing 7.5% sodium chloride, 10% dicalcium phosphate, 2.5% potassium carbonate, 2% magnesium sulfate, 1% elemental sulfur plus trace minerals, molasses and corn meal were readily consumed when combined with nitrogen sources to formulate 100% crude protein equivalent (CPE) mixtures. Cottonseed hulls were readily consumed (3.1% of body weight [BW] per day), but chopped straw (2.0% BW) and corn stover (1.4% BW) were very poorly consumed. Increasing nitrogen intake by the steers markedly increased cottonseed hull intake. Type of supplement and cottonseed hull intake (percent BW) were as follows: (a) negative control (no supplemental nitrogen source), 2.2%; (b) restricted 50% crude protein soybean meal control, 2.7%; and (c) 100% CPE supplements fed free choice, 3.1%. Growing steers gained an average of .54 kg daily during 140-day trials when fed cottonseed hulls free choice plus either biuret or urea 100% CPE supplements. Replacing 20% of the NPN nitrogen with fish meal or soybean meal nitrogen increased gains by 20%. Treating the soybean meal protein with .6% formaldehyde did not improve steer performance. Ruminal ammonia concentrations averaged 10 to 20 mg NH3-N/100 ml of ruminal fluid for steers fed the 100% CPE supplements. Monensin addition to the supplement resulted in a 1.9 acetate/propionate ratio compared to a 5.0 ratio for control steers but reduced supplement and cottonseed hull intake and steer performance.