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PubMed1984

Influence of feeding different amounts of milk on performance, health, and absorption capability of baby calves.

The influence of feeding high milk on performance, health, and absorption capability of the small intestine was studied in Holstein calves (eight males and eight females). Animals were kept in outdoor hutches bedded with straw. Treatments consisted of two quantities of milk: 1) 4.1 kg of whole milk from 3 to 48 days of age when calves were weaned and 2) gradually increasing milk from 4.1 to 7.0 kg during the first 2 wk of treatment and feeding 7.6 kg per day thereafter until day 42. Milk was reduced gradually during the 7th wk. Intake of milk averaged 4.1 and 6.7 kg per animal per day. Commercial starter, alfalfa hay, and water were offered ad libitum to all calves. Higher milk resulted in larger weight gains (615 versus 538 g/day) and less starter intake. Total dry matter intake, feed efficiency, and scour scores were not different between treatments, but rectal temperatures were greater on high milk. Female calves fed high milk showed less xylose absorption and more days medicated than females fed less milk.

Animal Feed↗

PubMed2002

Effect of dietary mannan oligosaccharides and(or) pharmacological additions of copper sulfate on growth performance and immunocompetence of weanling and growing/finishing pigs.

Two experiments were conducted to determine the efficacy of mannan oligosaccharides (MOS) fed at two levels of Cu on growth and feed efficiency of weanling and growing-finishing pigs, as well as the effect on the immunocompetence of weanling pigs. In Exp. 1, 216 barrows (6 kg of BW and 18 d of age) were penned in groups of six (9 pens/treatment). Dietary treatments were arranged as a 2 x 2 factorial consisting of two levels of Cu (basal level or 175 ppm supplemental Cu) with and without MOS (0.2%). Diets were fed from d 0 to 38 after weaning. Blood samples were obtained to determine lymphocyte proliferation in vitro. From d 0 to 10, ADG, ADFI, and gain:feed (G:F) increased when MOS was added to diets containing the basal level of Cu, but decreased when MOS was added to diets containing 175 ppm supplemental Cu (interaction, P < 0.01, P < 0.10, and P < 0.05, respectively). Pigs fed diets containing 175 ppm Cu from d 10 to 24 and d 24 to 38 had greater (P < 0.05) ADG and ADFI than those fed the basal level of Cu regardless of MOS addition. Pigs fed diets containing MOS from d 24 to 38 had greater ADG (P < 0.05) and G:F (P < 0.10) than those fed diets devoid of MOS. Lymphocyte proliferation was not altered by dietary treatment. In Exp. 2, 144 pigs were divided into six pigs/pen (six pens/treatment). Dietary treatments were fed throughout the starter (20 to 32 kg BW), grower (32 to 68 kg BW), and finisher (68 to 106 kg BW) phases. Diets consisted of two levels of Cu (basal level or basal diet + 175 ppm in starter and grower diets and 125 ppm in finisher diets) with and without MOS (0.2% in starter, 0.1% in grower, and 0.05% in finisher). Pigs fed supplemental Cu had greater (P < 0.05) ADG and G:F during the starter and grower phases compared to pigs fed the basal level of Cu. During the finisher phase, ADG increased when pigs were fed MOS in diets containing the basal level of Cu, but decreased when MOS was added to diets supplemented with 125 ppm Cu (interaction, P < 0.05). Results from this study indicate the response of weanling pigs fed MOS in phase 1 varied with level of dietary Cu. However, in phase 2 and phase 3, diets containing either MOS or 175 ppm Cu resulted in improved performance. Pharmacological Cu addition improved gain and efficiency during the starter and grower phases in growing-finishing pigs, while ADG response to the addition of MOS during the finisher phase seems to be dependent upon the level of Cu supplementation.

Animal Feed↗

PubMed1988

Effects of ionophores on cow herd production: a review.

Feeding ionophores to beef cows or replacement heifers fed harvested forages increases weight gain and improves feed efficiency. These responses are influenced by diet quality and body condition of the animal. These compounds may reduce postpartum interval to estrus, but this effect appears to be diminished if nutritional status is poor. Although ionophores do not alter fertility, they decrease age at puberty in the female. These changes in reproductive performance appear to be related to a hormonal response to an increased propionate:acetate ratio in the rumen characteristic of ionophore feeding. Responses to ionophores in milk yield and weight gain improvements in calves of ionophore-fed cows are variable. Length of gestation, incidence of dystocia, calf birth weights and percent calf crop are not altered by ionophore feeding. The potential to improve cow herd production through the use of ionophores depends primarily on forage quality and availability.

Animals↗

PubMed1982

Effects of photoperiod and castration on post-fast food intake and body weight gain in golden hamsters.

This experiment examined the effects of photoperiod and castration of post-food-restriction food intake and body weight gain in male golden hamsters (Mesocricetus auratus). Hamsters were ether castrated or sham-operated and housed in a 14:10 light-dark (LD) or a 8:16 LD cycle for 8 weeks. All animals were restricted to a 6 g of chow per day for 13 days and then returned to ad lib feeding. Following food restriction the hamsters gained weight rapidly without overeating. The long photoperiod (LD 14:10) increased post-restriction weight gain in castrated hamsters but decreased weight gain in gonadally intact animals. These differences in body weight gain were associated with significant group differences in feed efficiency (grams weight gain per gram eaten). The results suggest that changes in energy utilization may be more important than changes in energy intake in the adaptation of hamsters to food restriction.

Adaptation, Physiological↗

PubMed1994

Effect of the addition of live yeast (Saccharomyces cerevisiae) on growth and carcass quality of steers fed high-forage or high-grain diets and on feed digestibility and in situ degradability.

The effects of adding yeast culture (Saccharomyces cerevisiae, 5 x 10(9) live organisms/g of growth medium) at 10 g/steer daily to three diets consisting of 75% alfalfa silage and 25% barley, 96% corn silage and 4.0% soybean meal, or 75% dry-rolled barley and 25% alfalfa hay on performance of growing and finishing steers and carcass characteristics, feed digestibility, and degradability in the rumen were determined. In separate trials over 2 yr, the performance of steers fed the three diets with no supplementary live yeast (control; C) or with live yeast (Y) was determined using 72 Hereford steer calves in eight pens each year in a randomized complete block design. The diets were fed sequentially and the steers were randomized before diets were switched. Each year at the end of the high-grain feeding segment of the trial, the steers were slaughtered when ultrasound backfat was such that the carcass would grade A1 or A2 (Canadian grades). The digestibility of feed DM, CP, and NDF of the three diets was determined sequentially using six and eight mature, ruminally cannulated steers in 2 yr, respectively. The degradation characteristics of the three diets in the rumen were determined using the nylon bag technique in two steers for each additive treatment. In the 1st yr, the feed efficiency of the corn silage diet was lower (P < .05) for C than for Y steers (5.9 vs 6.8). Differences (P < .05) were not observed between C and Y steers for any of the performance or carcass characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed1998

Effect of energy source and escape protein on receiving and finishing performance and health of calves.

Two receiving and two finishing trials evaluated energy source and escape protein supplementation for calves. In receiving Trial 1, 398 calves (257 +/- 24 kg BW) were used in a 2 x 2 factorial arrangement of treatments. Energy sources were dry-rolled corn (DRC) and wet corn gluten feed (WCGF); each was fed without or with supplemental escape protein (EP). Calves fed WCGF gained slower (P < .05) and consumed less DM (P < .01) than calves fed DRC. Feed efficiency improved (P < .10) with EP supplementation. In finishing Trial 1, 240 calves (305 +/- 21 kg BW) were used. The arrangement of treatments was the same as in receiving Trial 1. Calves fed DRC/WCGF tended (P = .15) to be more efficient and consumed less DM (P < .05) than calves fed DRC. In receiving Trial 2, 315 calves (252 +/- 23 kg BW) were fed diets similar to those fed in receiving Trial 1. Calves fed WCGF consumed less DM (P < .01), gained similarly (P > .15), and were more efficient (P < .10) than calves fed DRC. In finishing Trial 2, 320 calves (298 +/- 23 kg BW) were fed diets containing DRC, DRC/WCGF, high-moisture corn (HMC), HMC/WCGF, and DRC/HMC; each was fed without or with supplemental EP. An energy source x protein supplement interaction was detected for gain (P < .05) and efficiency (P < .01). Results suggest that WCGF has a NEg greater than DRC in receiving diets and a NEg similar to that of DRC but lower than that of HMC in finishing diets.

Animal Feed↗

PubMed1980

Fiber sources for complete calf starter rations.

Complete calf starter rations containing either 1) alfalfa hay, 2) cottonseed hulls, or 3) alfalfa-beet pulp as sources of fiber were fed to Holstein heifer calves at two locations on a limited milk program from 3 days to 12 wk of age. Rations were isonitrogenous and similar in content of crude fiber and acid detergent fiber. Although growth and development were normal on all rations, calves fed the cottonseed hull ration consumed more starter and gained more body weight than calves fed the other sources of fiber. The similarity of feed efficiencies, rumen pH, and molar ratios of volatile fatty acids between rations indicated no appreciable differences in rumen development or function. The growth response of calves fed the cottonseed hull ration appeared to be a result of better ration acceptability for which no reason was evident. Calves raised at Puyallup gained more body weight than calves at Pullman, and these gains were made more efficiently. These location effects may be related to seasonal differences and greater demands for production of body heat. Although the incidence of scours was less for calves fed alfalfa hay starter, the incidence and severity of bloat were higher for that ration.

Animal Feed↗

PubMed1976

The effect of grassmeal and alfalfa meal on daily gain, thickness of backfat and on the esophagogastric region in bacon pigs.

In pigs dietary factors often are involved as causes of lesions in pars esophagea of the stomach. In experiments the primary purpose of which was to clarify the effect of grassmeal or alfalfa meal on growth, feed efficiency and carcass quality in bacon pigs, an influence of these feedstuffs on the growth rate and degree of esophagogastric lesions was detected. Pigs with these lesions had as an average a lower daily gain and less backfat than pigs without lesions.

Animal Feed↗

PubMed2006

Oral tolerance induction with antigen conjugated to cholera toxin B subunit generates both Foxp3+CD25+ and Foxp3-CD25- CD4+ regulatory T cells.

Oral administration of Ag coupled to cholera toxin B subunit (CTB) efficiently induces peripheral immunological tolerance. We investigated the extent to which this oral tolerance is mediated by CD25+CD4+ regulatory T cells (T(reg)). We found that total T(reg), KJ1-26+ T(reg) and CTLA-4+ T(reg) were all increased in Peyer's patches, mesenteric lymph nodes, and, to a lesser extent, in spleen of mice after intragastric administration of OVA/CTB conjugate, which also increased TGF-beta in serum. This could be abolished by co-administering cholera toxin or by treatment with anti-TGF-beta mAb. CD25+ T(reg), but also CD25-CD4+ T cells from OVA/CTB-treated BALB/c or DO11.10 mice efficiently suppressed effector T cell proliferation and IL-2 production in vitro. Following adoptive transfer, both T cell populations also suppressed OVA-specific T cell and delayed-type hypersensitivity responses in vivo. Foxp3 was strongly expressed by CD25+ T(reg) from OVA/CTB-treated mice, and treatment also markedly expanded CD25+Foxp3+ T(reg). Furthermore, in Rag1(-/-) mice that had adoptively received highly purified Foxp3-CD25-CD4+ OT-II T cells OVA/CTB feeding efficiently induced CD25+ T(reg) cells, which expressed Foxp3 more strongly than naturally developing T(reg) and also had stronger ability to suppress effector OT-II T cell proliferation. A remaining CD25- T cell population, which also became suppressive in response to OVA/CTB treatment, did not express Foxp3. Our results demonstrate that oral tolerance induced by CTB-conjugated Ag is associated with increase in TGF-beta and in both the frequency and suppressive capacity of Foxp3+ and CTLA-4+ CD25+ T(reg) together with the generation of both Foxp3+ and Foxp3-CD25- CD4+ T(reg).

Administration, Oral↗

PubMed2001

Studies on rye (Secale cereale L.) lines exhibiting a range of extract viscosities. 2. Rheological and baking characteristics of rye and rye/wheat blends and feeding value for chicks of wholemeals and breads.

Five rye lines exhibiting a wide range of extract viscosities were evaluated for the rheological and baking properties of their flours, individually and in blends with hard red spring wheat flour. Commercial cultivars of rye and triticale were included in the study as controls. Extract viscosities of rye flours were higher than those of corresponding wholemeals, indicating shifting of water-extractable arabinoxylan into flour during roller milling. Falling numbers of the rye flours correlated positively with their extract viscosities in the presence (r = 0.73, p < 0.05) or absence (r = 0.65, p < 0.05) of an enzyme inhibitor. Farinograms revealed the weakness of rye and triticale flours compared to wheat flour. Extract viscosities of rye flours were negatively correlated (r = -0.65, p < 0.05) with mixing tolerance index and positively correlated (r = 0.64, p < 0.05) with dough stability, suggesting a positive impact of extract viscosity on dough strength. Extract viscosity was negatively correlated (r = -0.74, p < 0.05) with loaf volume and specific volume (r = -0.73, p < 0.05) and positively correlated (r = 0.73, p < 0.05) with loaf weight of rye/wheat bread. Overall, the results indicated that 30% of flour from high or low extract viscosity rye could be incorporated into rye/wheat breads without seriously compromising bread quality. Inclusion of rye, particularly high extract viscosity rye, in chick diets seriously impeded growth performance and feed efficiency. Part of the arabinoxylan survived bread-making and exerted an effect on chicks, although substantially lower digesta viscosities were observed in chicks fed rye bread diets than in those fed rye wholemeals.

Animal Feed↗

PubMed1995

An in vitro procedure for studying enzymic dephosphorylation of phytate in maize-soyabean feeds for turkey poults.

An in vitro method was developed to predict inorganic P release from maize-soyabean poultry feeds containing supplemental phytase (EC 3.1.3.8), and to quantify the effect of acid phosphatase (EC 3.1.3.2), fungal protease (EC 3.4.23.6) and Aspergillus niger cellulase (EC 3.2.1.4) on phytate dephosphorylation. Pepsin (EC 3.4.23.1) and pancreatin digestion periods were preceded by a 30 min pre-incubation at pH 5.25 to simulate digestion in the crop of poultry. Pancreatin digestion was carried out in dialysis tubing, with a ratio of about 1:25 (v/v) between the digesta and dialysing medium, to simulate gradient absorption from the duodenum. The feed:water ratio was kept within physiological limits and a constant proportion of feed weight to digestive enzymes was maintained. There was a linear response to increasing dosages of phytase up to 1000 phytase units (FTU)/kg feed, and to increasing phosphate concentration in feeds. In vivo validation was performed with growing turkeys (1-3 weeks) fed on diets containing 12 g Ca/kg and 0, 500 or 1000 FTU phytase/kg in a factorial arrangement with 0, 1, 2 or 3 g supplemental phosphate/kg (from KH2PO4). After a simple transformation (variable/in vitro P = f (in vitro P)), amounts of P hydrolysed from feed samples by in vitro digestions correlated with 3-week body-weight gain (R 0.986, P < 0.0001), toe ash (R 0.952, P < 0.0001), feed intake (R 0.994, P < 0.0001) and feed efficiency (R 0.992, P < 0.0001). The dephosphorylating ability of phytase in vitro was significantly enhanced (P < 0.05) by the addition of acid phosphatase. Fungal acid protease and Aspergillus niger cellulase also enhanced the dephosphorylation process in vitro.

Acid Phosphatase↗

PubMed2003

Zinc supplementation alleviates heat stress in laying Japanese quail.

The study was conducted to determine whether zinc supplementation could alleviate the detrimental effects of high ambient temperature (34 degrees C) on egg production, digestibility of nutrients and antioxidant status in laying Japanese quail. Quail (n = 180; 52 d old) were divided into six groups (n = 30/group) and were fed a basal diet or the basal diet supplemented with 30 or 60 mg of zinc (ZnSO(4). H(2)O)/kg diet. Birds were kept at 22 degrees C and 58% relative humidity (RH). At 13 wk of age, the thermoneutral (TN) groups remained at the same temperature, whereas the heat-stress (HS) groups were kept in an environmentally controlled room at 34 degrees C and 42% RH for 3 wk. Heat exposure decreased egg production in birds fed the basal diet (P = 0.001). Linear increases in feed intake (P = 0.01) and egg production (P = 0.004) and improved feed efficiency (P = 0.01) and egg quality variables (P 0.05). Results of the present study suggest that supplementation with 60 mg zinc/kg diet protects quail by reducing the negative effects of heat stress.

Animal Nutritional Physiological Phenomena↗

PubMed1998

Effects of fish meal and sodium bentonite on daily gain, wool growth, carcass characteristics, and ruminal and blood characteristics of lambs fed concentrate diets.

We evaluated the effects of replacing some soybean meal (SBM) protein with fish meal (FM) protein in diets adequate and slightly deficient in CP, with or without .75% sodium bentonite (NaB) on performance and ruminal and blood metabolites of individually fed Suffolk lambs. Diets were based on corn, SBM, and cottonseed hulls. In Exp. 1, five lambs were assigned to each of the three dietary treatments (11% CP with 3% FM, 13% CP with 0 or 3% FM). Lambs fed diets that contained 11% CP with 3% FM or 13% CP with 0% FM had similar DMI and ADG. Gain and feed efficiency were slightly improved (P = .18) by the 13% CP diet with 3% FM. In Exp. 2, 32 lambs were assigned to four dietary treatments (13.5% CP of DM) in a 2 x 2 factorial arrangement (0 or 3% FM, and 0 or .75% NaB on an as-fed basis). The DMI and ADG were increased (P < .05) by FM and NaB supplementation. Interactions (P < .05) revealed that NaB increased DMI, ADG, gain per feed (g/kg of DMI), and plasma urea N concentration in the absence of FM but not in the presence of FM in the diet. Neither FM nor NaB influenced (P = .25) wool growth. Total ruminal VFA were increased (P < .06) by FM and NaB. Differences in mineral content of phalanx bone, liver, and kidney were small and may be related to the mineral content of diets and the effect of NaB on mineral solubilities. Similar DMI and ADG of lambs fed FM and NaB separately and in combination suggest that their beneficial effect is not additive.

Animal Feed↗

PubMed2007

Nutritional evaluation of high-digestible sorghum for pigs and broiler chicks.

Two experiments were conducted to evaluate the nutritional quality of 2 varieties of Purdue high-digestible sorghum (PHD1 and PHD2) and a normal sorghum, compared with corn, in diets of pigs and broiler chicks. In Exp. 1, 12 pigs (average BW, 55 kg) fitted with ileal T-cannula were fed 4 diets containing 946 g of corn or sorghum (PHD1, PHD2, and normal) per kg in a 2-period crossover design (i.e., each pig received 2 diets over a 2-wk period with 6 pigs per dietary treatment) to determine apparent ileal or total tract digestibility of nutrients and energy. There was no difference in the ileal or total tract digestibility of DM, energy, P, Ca, or N among dietary treatments. In Exp. 2, a total of 192 broiler chicks were grouped by weight into 8 blocks of 4 cages each with 6 chicks per cage, and cages were assigned randomly to 1 of the 4 dietary treatments within each block. Chicks were fed corn-soybean meal (SBM) or sorghum-SBM diets for 21 d to determine apparent total tract retention and then switched to diets containing 935 g of the corresponding corn or 1 of the 3 sorghum varieties per kg for 7 d to determine apparent ileal digestibility and total tract retention. Apparent ileal digestibilities of DM and P, as well as energy, were not different in chicks fed diets containing 935 g of corn or 1 of the 3 sorghum varieties per kg. However, apparent total tract retention of DM, energy, and N in chicks fed corn was greater (P < 0.05) than those fed 1 of the 3 sorghum varieties. Although the apparent ME content of corn was greater than PHD1 and normal sorghum (P < 0.01), it was not different from PHD2 sorghum. There was no difference in apparent total tract retention of DM between chicks fed the corn-SBM and PHD-SBM diets, but it was greater (P < 0.05) in chicks fed the corn-SBM diet than those fed the normal sorghum-SBM diet. Apparent total tract retention of N in chicks fed the PHD1-SBM diet was lower (P < 0.05) than in those fed the corn-SBM diet but greater (P < 0.05) than in chicks fed the normal sorghum-SBM meal diet. No difference in the apparent ME content between the corn-SBM and PHD2-SBM diets was observed, but it was greater (P < 0.05) for the corn-SBM diet than the PHD1- or normal sorghum-SBM diet. Weight gain, feed intake, and feed efficiency were not different in chicks fed the corn-SBM or sorghum-SBM diets. Sorghum could serve as a substitute for corn in cereal grain-SBM diets for pigs and broiler chicks.

Animal Feed↗

PubMed1979

Effects of feeding tylosin to layers exposed to Mycoplasma gallisepitcum.

Two experiments are reported in which the effect of tylosin upon the development of Mycoplasma gallisepticum (MG) infection in replacement layers was monitored by serological and cultural methods. Concentrations of tylosin tested included 0, 22, 38.5, and 55 ppm. Egg production and feed consumption data were collected for one year. Tylosin slowed the rate of spread of MG infection as measured by serological and cultural methods. The effect of tylosin on the spread of MG infection was dose related. Hen day egg production peaked at 85 to 87% in the mediated groups, while controls peaked at 81 to 84%. The magnitude of tylosin effect on production increased with time to a maximum difference of 10 to 12% at 52 weeks. Feed efficiency was markedly improved by all concentration of tylosin ranging from 5% at peak production to 12 to 18% at 52 weeks. The incidence of shell-less or soft shelled eggs was markedly reduced in the tylosin treated group.

Animal Feed↗

PubMed2003

beta-Mannanase ameliorates viscosity-associated depression of growth in broiler chickens fed guar germ and hull fractions.

High concentrations of guar meal in broiler chicken diets reduce body weight and feed efficiency. The increased intestinal viscosity that is responsible for reduced measures of performance results from residual guar gum present in guar meal. Two experiments were designed to study the effects of 2 guar meal fractions at 3 different concentrations, germ (0, 5.0, and 7.5%) and hull (0, 2.5, and 5.0%), and the effectiveness of a beta-mannanase at three levels (0, 1x, and 4x; 1x = 1.09 x 10(5) units/ kg) on broiler growth and feed conversion. Growth and performance were measured as a function of intestinal viscosity. Addition of the germ fraction to rations did not reduce body weight, although feed conversion ratio was increased at 7.5% of the diet. Intestinal viscosity also increased significantly at this level. Enzyme addition significantly reduced intestinal viscosity. Due to an interaction that was present between hull and enzyme concentration, each treatment was compared separately. Inclusion of the hull fraction significantly reduced body weight at both levels of inclusion and increased feed conversion ratio at 5% inclusion. Addition of the enzyme significantly increased body weight and reduced feed conversion ratio in diets containing guar hull fractions. Supplementation of beta-mannanase to feeds containing either fraction of guar meal reduced intestinal viscosity and alleviated the deleterious effects associated with guar meal feeding.

Animal Nutritional Physiological Phenomena↗

PubMed1996

The effect of dietary fat inclusion on growth, carcass characteristics, and chemical composition of rabbits.

Two hundred ten Californian x New Zealand White rabbits were used to study the influence of diet and slaughter weight (2.0, 2.25, and 2.5 kg) on feed intake, growth, feed efficiency, carcass characteristics, and body chemical composition. Seven diets were formulated to contain 24% ADF: Diet C (control) had no added fat; Diets T, O, and S contained 3% of added beef tallow, oleins, and soybean oil, respectively; Diets TWS, OWS, and SWS contained the same level and types of fat plus 18% heated whole soybeans (WS) to increase the dietary fat by 3%. Fat addition did not affect ADG or dressing percentage, but it improved feed:gain ratio (.06 for each 1% of dietary fat, P < .001). Although the main measurements of carcass were not influenced by fat addition, the rabbits fed diets containing the highest fat percentage had the highest weights of perirenal (P < .001) and scapular (P < .01) depots and the highest body fat content (P < .01). The increase in slaughter weight improved all the desirable carcass characteristics measured but imparied feed:gain (by 13%, P < .001). Increasing slaughter weight also increased the perirenal and scapular fat depots by 40 an 24%, respectively (P < .001)< and the body fat content by 28% (P < .01). There were no differences in the utilization of animal and vegetable fats, and only for some traits ADG, feed intake, kidney weights) did the diets with soybean oil result in better responses than those with oleins. The results indicate that fat addition to fibrous diets extends the rabbit's growing period without impairing the feed:gain ratio. The joints of rabbits killed at heavier weights have more desirable weights for marketing the carcass on a retail cut basis.

Animals↗

PubMed1980

Effect of avoparcin and monensin on performance of finishing heifers.

One-hundred and fifty crossbred yearling-heifers, averaging 264 +/- 17 kg were fed a 77% barley diet for 140 days to evaluate the effect of 0, 33, 49.5 and 66 ppm avoparcin and 33 ppm monensin on growth rate, feed efficiency, carcass quality and ruminal volatile fatty acid (VFA) concentration. Heifers were allotted by weight to 25 pens (six head per pen) in a randomized complete block design of five treatments and five replicates per treatment. On day 140, rumen fluid was obtained from a randomly selected replicate of six heifers from each treatment for VFA analysis. Carcass data and liver samples were obtained at slaughter on day 147. All avoparcin-fed cattle consumed less feed per unit gain (P less than .05) than did those in the control group. Feed intakes of the monensin-fed heifers and the heifers fed 49.5 ppm avoparcin were lower (P less than .05) than those of the control group. There were no differences (P greater than .05) between treatments for measured carcass, liver or rumen parameters.

Animals↗