Grain-based Diet Research Articles

Escherichia coli O157:H7 populations in ruminants can be reduced by orange peel product feeding.

Foodborne pathogenic bacteria such as Escherichia coli O157:H7 are threats to the safety of beef. Citrus peel and dried orange pulp are by-products from citrus juice production that have natural antimicrobial effects and are often incorporated into least-cost ration formulations for beef and dairy cattle. This study was designed to determine if orange peel and pulp affected E. coli O157:H7 populations in vivo. Sheep (n = 24) were fed a cracked corn grain-based diet that was supplemented with a 50-50 mixture of dried orange pellet and fresh orange peel to achieve a final concentration (dry matter basis, wt/wt) of 0, 5, or 10% pelleted orange peel (OP) for 10 days. Sheep were artificially inoculated with 10(10) CFU of E. coli O157:H7 by oral dosing. Fecal shedding of E. coli O157:H7 was measured daily for 5 days after inoculation, after which all animals were humanely euthanized. At 96 h postinoculation, E. coli O157:H7 shedding was reduced (P < 0.05) in sheep fed 10% OP. Populations of inoculated E. coli O157:H7 were reduced by OP treatment throughout the gastrointestinal tract; however, this reduction reached significant levels in the rumen (P < 0.05) of sheep fed 10% OP diets. Cecal and rectal populations of E. coli O157:H7 were reduced (P < 0.05) by inclusion of both 5 and 10% OP diets. Our results demonstrate that orange peel products can be used as a preharvest intervention strategy as part of an integrated pathogen reduction scheme.

Short communication: Effect of breed on performance and carcass characteristics of Mexican hair sheep

To determine the effect of breed on growth performance and carcass characteristics in Mexican hair sheep, 48 lambs (average 38.9 &plusmn; 1.56 kg body weight, BW) were used in a completely randomized experimental design. The breed types assessed were 16 Pelibuey (PB), 16 Pelibuey x Katahdin (PB-KT) crossbred and 16 Pelibuey x Dorper (PB-DP) crossbred lambs. The lambs were fed a maize grain-based diet (88% concentrate and 12% forage) containing 155 g CP and 12.13 MJ ME/kg DM. The growth performance trial lasted 45 days. The average daily gain was significantly higher for the PB breed than for the PB-KT and PB-DP cross-breds. Feed intake in the PB and PB-KT was significantly higher than in the PB-DP. The feed conversion ratio was lower for the PB than for PB-KT and PB-DP lambs. Hot carcass dressing and leg perimeters were significantly lower for the PB than for the PB-DP lambs, and similar to that of the PB-KT lambs. The lowest dorsal fat values were measured in the PB breed, compared with both the PB-KT and PB-DP cross-breds. Mesenteric fat (as % of BW) in the PB was significantly higher than in PB-KT and PB-DP lambs. Empty rumen and small intestine weights (as % of BW) in the PB lambs were significantly higher than in the PB-DP lambs, but their large intestine was significantly smaller than in the other two breeds. It was concluded that the PB lambs have a better growth performance and carcass characteristics than the PB-DM lambs, but similar to that of the PB-KT lambs.Keywords: Dressing percentage, longissimus dorsi, organ weights, lambs, Pelibuey, Katahdin, Dorper

Assessment of zinc deficiency and effect of dietary carrot, amchur and onion on zinc status during repletion in zinc‐deficient rats

Food acidulants, β-carotene-rich vegetables and sulfur compound-rich Allium spices are known to improve zinc bioaccessibility from food grains. This animal study evaluated the positive influence of these promoters of zinc bioaccessibility on zinc status during zinc repletion in Wistar rats previously rendered zinc-deficient by feeding a zinc-deficient semi-synthetic diet for 4 weeks. Groups of these zinc-deficient animals were subsequently maintained on a zinc-containing grain-based diet for 2 weeks. Various experimental diets consisted of the grain-based diet supplemented with (1) carrot, (2) onion, (3) amchur, (4) carrot + amchur and (5) onion + amchur. Zinc deficiency was confirmed by lower zinc concentration in tissues and bones and lower activity of zinc-containing enzymes. Zinc concentration was 10-15% lower in serum, liver and kidney of zinc-deficient rats. Bone weight in zinc-deficient rats was 20% lower than that in normal rats. Activities of zinc-containing enzymes (hepatic superoxide dismutase and alcohol dehydrogenase and serum alkaline phosphatase) were lower in the zinc-deficient group. Animals fed diets supplemented with these promoters of zinc bioaccessibility showed better zinc status in tissues and bones compared with those repleted with the control stock diet. This animal study supports the claim of promoters of zinc bioaccessibility for improving zinc status, which may find practical application.

Effects of vitamin E on color stability and palatability of strip loin steaks from cattle fed distillers grains

The objective of this study was to determine the effect of preslaughter antioxidant supplementation to cattle fed wet distillers grains on carcass yield and quality grade, and on the color stability and consumer acceptability of steaks. Two hundred five crossbred steers were fed 35% wet distillers grains with the supplementation of 4 different levels of α-tocopheryl acetate: 0, 125, 250, and 500 IU•animal(-1)•d(-1) for 97 d. Chuck rolls (n = 69) and strip loins (n = 185) were collected and processed at 4 and 7 d postslaughter, respectively. Chucks were ground and separated into 0.23-kg samples. Strip loins were faced and cut into 2.54-cm steaks and packaged in a polyvinyl chloride overwrapped (PVC) package, a vacuum package, or modified atmosphere packages (MAP) for further color, α-tocopherol, objective tenderness, palatability, and proximate analysis. Color was measured objectively using a HunterLab Miniscan XE spectrophotometer (HunterLab Associates Inc., Reston, VA) and subjectively by a trained color panel, and a consumer panel was used to indicate which treatments affected retail acceptability and purchase decisions. Warner-Bratzler shear force measurements were used for objective tenderness, and a trained panel assessed subjective palatability characteristics. Instrumental color measurements revealed little difference for ground beef in both PVC and MAP packages, but diets with 500 and 250 IU•animal(-1)•d(-1) of vitamin E had a longer (P < 0.05) retention of redness and yellowness in steaks as compared with steaks from animals receiving less vitamin E. Subjective color evaluation for strip steaks indicated that greater vitamin E was more likely (P < 0.05) to maintain color stability, overall acceptability, and consumer purchase preference while decreasing percentage of discoloration. No significant differences (P > 0.10) were observed for objective tenderness and sensory attributes of strip steaks, and no differences (P > 0.10) were observed in protein, fat, and moisture percentages of ground beef. Lipid oxidation analysis indicated that steaks packaged in PVC for 7 d and MAP for 1, 3, and 7 d, and ground beef packaged in MAP and PVC for 0 and 7 d of retail display required greater inclusion of vitamin E (500 and 250 IU•animal(-1)•d(-1)) to remain below the 2.28 mg of malonaldehyde/kg threshold. Ultimately, 500 IU•animal(-1)•d(-1) of vitamin E should be supplemented to cattle fed wet distillers grain-based diets when products are packaged in MAP to maximize retail shelf life.

Influence of rumen-protected lysine supplementation on growth performance and plasma amino acid concentrations in growing cattle offered the maize stalk silage/maize grain-based diet

The effects of rumen-protected lysine (RPLys) supplementation on growth performance, plasma amino acid (AA) concentrations and blood biochemical indices were investigated in a 84-d growth trial using 56 Limousin × Fuzhou F1 crossbred bulls (13 mo of age, average initial BW = 372.9 ± 22.4 kg) fed the maize stalk silage/maize grain-based diet. All animals were fed individually the same basal diet containing 500 g/kg maize stalk silage, 340 g/kg ground maize grain and 160 g/kg dry mixed concentrate (DM basis). Incremental amounts (0, 5, 10 or 15 g/d) of RPLys were added to the basal diet. Increasing supplemental RPLys level did not alter ( P>0.05) dietary dry matter intake, but increased average daily gain (quadratic effect; P=0.036) and feed efficiency (quadratic effect; P=0.030) with maximum values achieved at 10 g/d RPLys supplementation. Supplementing dietary RPLys linearly ( P=0.009) increased plasma Lys and quadratically ( P=0.014) decreased plasma urea nitrogen, suggesting that added RPLys has been effectively utilized for tissue growth and Lys seems to be a first-limiting amino acid for growing cattle fed the maize stalk silage/maize grain-based diet. In summary, when growing cattle were fed maize silage/maize grain-based diets adequate in MP (MP = 780.9 g/d) but inadequate in Lys, their average daily gain and feed efficiency were promoted by dietary supplementation of RPLys.

Orange Peel Products Can ReduceSalmonellaPopulations in Ruminants

Salmonella can live undetected in the gut of food animals and be transmitted to humans. Animal diets can impact intestinal populations of foodborne pathogens, including Salmonella spp. Orange juice production results in a waste product, orange peel and orange pulp, which has a high nutritive value and is often included in cattle diets as a least-cost ration ingredient. Here we show that the inclusion of orange peel products reduced Salmonella Typhimurium populations in the gut of experimentally inoculated sheep. Sheep (n=24) were fed a cracked corn grain-based high grain diet that was supplemented with a 50%/50% (dry matter [DM], w/w) mixture of dried orange pellet and fresh orange peel to achieve a final concentration (DM, basis) of 0%, 10%, or 20% orange product (OP) for 10 days before inoculation with Salmonella Typhimurium. Sheep were experimentally inoculated with 10(10) colony forming units Salmonella Typhimurium, and fecal samples were collected every 24 h after inoculation. Sheep were humanely euthanized at 96 h after oral Salmonella inoculation. Populations of inoculated Salmonella Typhimurium were numerically reduced by OP treatment throughout the gastrointestinal tract, and this reduction only reached significant levels in the cecum (p<0.05) of sheep fed 10% OP diets. Apparent palatability issues decreased the consumption of OP in sheep fed 20% OP to intake levels below that of 10% OP (approximately 7% dry matter intake [DMI]/d feed refusal), thereby reducing the potential effects of OP feeding at this higher level. Our results demonstrate that orange peel and pellets are environmentally friendly and low-cost products that can be used as a pre-harvest intervention as part of an integrated pathogen reduction scheme.

Dietary monensin level, supplemental urea, and ractopamine on fecal shedding of Escherichia coli O157:H7 in feedlot cattle1

Inclusion of distillers grains (DG) in cattle diets has been shown to increase fecal shedding of Escherichia coli O157:H7. It is hypothesized that altered gut fermentation by DG may be responsible for the positive association. Therefore, feed additives affecting ruminal or hindgut fermentation of DG also may affect fecal shedding of E. coli O157:H7. The objectives of the study were to evaluate effects of monensin (33 or 44 mg/kg of DM), supplemental urea (0, 0.35, or 0.70% of DM), and ractopamine (0 or 200 mg/steer daily administered during the last 42 d of finishing) in a steam-flaked corn grain-based diet containing 30% wet sorghum DG on fecal shedding of E. coli O157:H7. Seven hundred twenty crossbred beef steers, housed in 48 pens (15 steers/pen), were assigned to dietary treatments in a randomized complete block design with a 2 × 3 × 2 factorial treatment arrangement. Fresh pen floor fecal samples (10 per/pen) were collected every 2 wk for 14 wk (July through November) and cultured for E. coli O157:H7. Isolation of E. coli O157:H7 was by selective enrichment of fecal samples in an enrichment broth, immunomagnetic separation, followed by plating onto a selective medium. Samples that yielded sorbitol-negative colonies, which were positive for indole production, O157 antigen agglutination, and contained rfbE, fliC, and stx2 were considered positive for E. coli O157:H7. Fecal prevalence data were analyzed as repeated measures using negative binomial regression to examine effects and interactions of sampling day, urea, monensin, and ractopamine. Mean fecal prevalence of E. coli O157:H7 was 7.6% and ranged from 1.6 to 23.6%. Cattle fed monensin at 44 mg/kg of feed had less (P = 0.05) fecal E. coli O157:H7 prevalence than cattle fed 33 mg/kg (4.3 vs. 6.8%). Although the reason for the reduction is not known, it is likely because of changes in the microbial ecosystem induced by the greater amount of monensin in the hindgut. Supplemental urea at 0.35 or 0.70% had no effect (P = 0.87) on fecal shedding of E. coli O157:H7. Fecal prevalence of E. coli O157:H7 were 5.3, 5.7, and 5.9% for groups fed 0, 0.35, and 0.7% urea, respectively. The inclusion of ractopamine at 0 or 200 mg/(animal•d) had no effect (P = 0.89) on fecal prevalence of E. coli O157:H7 (4.4 vs. 4.0%). Additional research is needed to confirm the reduction in fecal shedding of E. coli O157:H7 in cattle fed monensin at 44 mg/kg of feed compared with cattle fed 33 mg/kg of feed.

Beef cattle selected for increased muscularity have a reduced muscle response and increased adipose tissue response to adrenaline

The aim of this experiment was to evaluate the impact of selection for greater muscling on the adrenaline responsiveness of muscle, adipose and liver tissue, as reflected by changes in plasma levels of the intermediary metabolites lactate, non-esterified fatty acids (NEFA) and glucose. This study used 18-month-old steers from an Angus herd visually assessed and selected for divergence in muscling for over 15 years. Ten low muscled (Low), 11 high muscled (High) and 3 high muscled heterozygotes for myostatin mutation (HighHet) steers were challenged with adrenaline doses ranging between 0.2 to 3.0 μg/kg live weight. For each challenge, 16 blood samples were taken between −30 and 130 min relative to adrenaline administration. Plasma was analysed for NEFA, lactate and glucose concentration and area under curve (AUC) over time was calculated to reflect the tissue responses to adrenaline. Sixteen basal plasma samples from each animal were also assayed for growth hormone. Muscle glycogen and lactate concentration were analysed from four muscle biopsies taken from the semimembranosus, semitendinosus and longissimus thoracis et lumborum of each animal at 14, 90 and 150 days on an ad libitum grain-based diet and at slaughter on day 157. In response to the adrenaline challenges, the High steers had 30% lower lactate AUC than the Low steers at challenges greater than 2 μg/kg live weight, indicating lower muscle responsiveness at the highest adrenaline doses. Aligning with this decrease in muscle response in the High animals were the muscle glycogen concentrations which were 6.1% higher in the High steers. These results suggest that selection for muscling could reduce the incidence of dark, firm, dry meat that is caused by low levels of glycogen at slaughter. At all levels of adrenaline challenge, the High steers had at least 30% greater NEFA AUC, indicating that their adipose tissue was more responsive to adrenaline, resulting in greater lipolysis. In agreement with this response, the High steers had a higher plasma growth hormone concentration, which is likely to have contributed to the increased lipolysis evident in these animals in response to adrenaline. This difference in lipolysis may in part explain the reduced fatness of muscular cattle. There was no effect of selection for muscling on liver responsiveness to adrenaline.

Effects of starch and fibre in pelleted diets on nutritional status of mule deer (Odocoileus hemionus) fawns

To compare the effects of a low-starch, high-fibre diet [LSHF; 51.6% neutral detergent fibre (NDF), 3.0% starch, 14.8% crude protein (CP)] and a high-starch, low-fibre diet (HSLF; 33.3% NDF, 20.0% starch, 19.6% CP) on the nutritional status of captive exotic ruminants, 16 mule deer (Odocoileus hemionus) were fed one of these two diets ad libitum with ≤25% alfalfa hay cubes from 10 days to 68 weeks of age. During five sampling periods beginning in November and spaced 6-12 weeks apart thereafter, feed intake, rumen and blood chemistry, faecal scores, growth and body condition were measured. Dry matter intake, digestible energy intake, time spent ruminating and feeding and blood acetate concentration were greater for deer fed LSHF (p < 0.05 for all). Lower dietary CP led to reduced blood urea nitrogen for deer consuming LSHF (p = 0.004). Deer had the same faecal scores, growth and body fat among treatments (all p > 0.05). These findings show pelleted diets with less starch, more fibre, and reduced protein met the energy and protein requirements of growing mule deer, a medium-sized browsing ruminant, as well as traditional grain-based diets while more closely mimicking natural forages and stimulating a more natural feeding behaviour.

Effect of xylanase and β-glucanase on growth performance and nutrient digestibility in piglets fed wheat–barley-based diets

There is increasing interest in the use of exogenous enzymes to improve diet digestibility and performance of pigs fed mixed grain-based diets. The potential of combination of carbohydrase (xylanase and β-glucanase ) to enhance nutrient digestibility and performance was examined in the present study using 160 crossbred pigs (Landrace × Large White) of initial mean BW of 7.4 kg. Pigs were randomly assigned to four dietary treatments with 4 pigs per pen and 10 pens per diet for a 42-d feeding period. The diets were: Control (T1, 92% of DE requirement of NRC, 1998, with no enzymes), and control plus carbohydrase combination. The enzyme was added at 50 (T2), 100 (T3) and 200 g/MT (T4). Celite was used as an indigestible marker and feed was available to pigs ad libitum. Pigs were weighed at 0, 3 and 6 weeks of the experiment and fecal samples were collected for 3 days at the end of week 5. On average, piglets grew 525 g/d, consumed 845 g/d, and exhibited mean FCR of 1.59. Weight gain and feed intake did not differ (P > 0.05) among treatments, however, FCR for the overall period was better (P < 0.05) for pigs fed diets supplemented with 200 g/MT enzyme compared with those fed the control diet. The FCR for the overall period were 1.66, 1.59, 1.60 and 1.57 (SE = 0.07) for T1, T2, T3 and T4, respectively. Faecal digestibility of energy and protein did not differ (P > 0.05) among treatments, however improvement in performance was observed, suggesting improved nutrient absorption in the ileum. Digestibility of NSP and of some individual sugars (arabinose, xylose, mannose and glucose) numerically increased (P > 0.05) with enzyme supplemented diets relative to the control. The digestibility of NSP improved by 2.7 to 5.6% in the carbohydrase-supplemented compared to the control diet. It can be concluded that adding a specific proportions of blend of exogenous xylanase and β-glucanase enzymes to mixed grain-based diets improved performance in weaned pigs.

Effect of nitrogen supplementation on urea kinetics and microbial use of recycled urea in steers consuming corn-based diets1

We studied the effects of supplementing N as distillers dried grains with solubles (DDGS) or urea to steers consuming corn-based diets. Six ruminally and duodenally cannulated steers (244 kg) were used in 2 concurrent 3 x 3 Latin squares and fed 1 of 3 corn-based diets: control (10.2% CP), urea (13.3% CP), or DDGS (14.9% CP). Periods were 14 d, with 9 d for adaptation and 5 d for collection of urine and feces. Urinary (15)N(15)N-urea enrichments, resulting from venous infusions of (15)N(15)N-urea, were used to measure urea kinetics. Dry matter intake (6.0 kg/d) was not affected by treatment, but N intake differed (99, 151, and 123 g/d for the control, DDGS, and urea treatments, respectively). Urea-N synthesis tended to be greater (P = 0.09) for DDGS (118 g/d) than for the control treatment (52 g/d), with the urea treatment (86 g/d) being intermediate. Urea-N excreted in the urine was greater (P < 0.03) for the DDGS (35 g/d) and urea treatments (29 g/d) than for the control treatment (13 g/d). Gastrointestinal entry of urea-N was not statistically different among treatments (P = 0.25), but was numerically greatest for DDGS (83 g/d), intermediate for urea (57 g/d), and least for the control (39 g/d). The amount of urea-N returned to the ornithine cycle tended to be greater (P = 0.09) for the DDGS treatment (47 g/d) than for the urea (27 g/d) or control treatment (16 g/d). The fraction of recycled urea-N that was apparently used for anabolism tended (P = 0.14) to be greater for the control treatment (0.56) than for the DDGS treatment (0.31), with the urea treatment (0.45) being intermediate, but no differences were observed among treatments in the amount of urea-N used for anabolism (P = 0.66). Urea kinetics in cattle fed grain-based diets were largely related to the amount of N consumed. The percentage of urea production that was captured by ruminal bacteria was greater (P < 0.03) for the control treatment (42%) than for the DDGS (25%) or urea treatment (22%), but the percentage of duodenal microbial N flow that was derived from recycled urea-N tended (P = 0.10) to be greater for the DDGS treatment (35%) than for the urea (22%) or control treatment (17%). Thus, ruminal microbes were more dependent on N recycling when the protein supplement was largely resistant to ruminal degradation.

Phosphorus requirement and excretion of finishing beef cattle fed different concentrations of phosphorus1

Phosphorus is an expensive nutrient to supplement, and excess may lead to manure P challenges. Therefore, minimizing dietary P to meet requirements is important. Two experiments were conducted to determine the P requirement of finishing cattle (Exp. 1) and to evaluate the effects of feeding different P concentrations on the quantity and route of P excretion (Exp. 2). In Exp. 1, 60 heifers (BW = 278 kg +/- 17 kg) were individually fed 1 of 5 dietary P concentrations (0.10, 0.17, 0.24, 0.31, or 0.38% P). Cattle performance, plasma P concentration, bone characteristics, and bone P concentration were used to determine the P requirement. Intake and ADG increased quadratically (P < 0.01) as dietary P increased. Plasma P in heifers receiving the 0.10% treatment was less (P < 0.01) than the other treatments and suggested that these heifers were experiencing a P deficiency. Total ash weight of the phalanx bones increased linearly (P < 0.01) as dietary P increased. In Exp. 2 using a 5 x 5 Latin square design, 5 different diets varying in P concentration (0.12, 0.27, 0.42, 0.30, and 0.36% P) were fed to steers to evaluate route and quantity of P excreted. Steers excreted little (1.78 g/d on average) P in the urine as a percentage of total P excretion. Steers on the 0.12% P diet excreted very little P in urine (0.50 g/d). Excretion of P was less (P < 0.05) for the cattle fed 0.12% P compared with all other treatments. Results from cattle performance, plasma P concentrations, and bone characteristics indicate that the heifers fed 0.10% P were experiencing a deficiency and the P requirement of finishing heifers is between 0.10 and 0.17% P. Dietary P concentrations of 0.10 to 0.17% P resulted in decreased P excretion. Supplementation of mineral P is unnecessary in grain-based feedlot diets because dietary P will greatly exceed the requirements (<0.17%).

Effect of ractopamine hydrochloride and zilpaterol hydrochloride on growth, diet digestibility, intake and carcass characteristics of feedlot lambs

The effects of the β-adrenergic agonists ractopamine hydrochloride (RH; 0.35, 0.70 and 1.05 mg kg − 1 of BW d − 1 ) and zilpaterol hydrochloride (ZH; 0.10, 0.20 and 0.30 mg kg − 1 of BW d − 1 ) on growth performance and carcass characteristics were determined in 84 Dorper × Katahdin lambs (12 lambs per treatment), that were randomly assigned to a complete block design during a 42-day feeding trial. Lambs were fed a corn grain-based diet (18.71% CP and 12.9 MJ/kg ME). Nutrient digestibility of diets and blood serum metabolites were also determined. There were no significant ( P > 0.05) differences in growth characteristics by effect of ZH or RH administration. However, lambs final weight, total weight gain and ADG increased linearly ( P < 0.05) as levels of both β-adrenergic agonist increased. RH or ZH administration did not affect feed efficiency, diet digestibility or particular blood serum metabolites of lambs. Carcass characteristics of lambs consuming ZH were significantly better ( P < 0.01) than RH or control lambs; RH produced significant linear response on carcass weight, dressing percentage, longissimus muscle area, carcass conformation and quality grade, and improved quadratically ( P < 0.05) fat thickness and USDA yield grade of lamb carcasses. On the other hand, increasing levels of ZH decreased linearly ( P > 0.01) fat thickness and improved ( P > 0.05) USDA yield grade and carcass quality grade. Both β-adrenergic agonists improved carcass characteristics; although greater improvements were obtained with ZH than RH for most carcass characteristics.

Effects of duration of zilpaterol hydrochloride supplementation on growth performance, carcass traits and meat quality of grain-fed cull cows

Several studies have shown that feeding of an energy-dense diet over short periods to cull cows could be profitable in terms of increased saleable yield and improved carcass conditions. Although the application of growth promoters, such as anabolic implants and beta agonists, in finishing of cull cows have been recorded, there is no conclusive evidence as to the timing and duration of beta agonists in cull cow production. In this study, 288 cull cows with four or more permanent incisors and varying weights and body conditions were divided into four treatment groups so that variation in age, weight and body condition were equally distributed among groups. One group received concentrate feed without any beta agonist (C), whereas the other three groups also received concentrate feed with zilpaterol hydrochloride (6 p.p.m.) for 20 (Z20), 30 (Z30) or 40 (Z40) days, respectively, followed by a 2-day withdrawal. Animals were adapted for 10 days on a grain-based diet and fed an additional 40 days before slaughter. Growth rate and efficiency (live and carcass), trimmed meat yield and meat tenderness (Warner Bratzler shear force and sensory) of the aged (10 days) m. longissimus thoracis (LT) and m. semitendinosus (ST) were recorded. In general, Z cows had higher carcass gains and efficiency of gain than C cows (P < 0.05). In addition, Z carcasses showed higher proportional trimmed meat yields than C carcasses (P < 0.05). No significant differences in tenderness measurements were recorded for LT or ST. In general, supplementation of zilpaterol for 30 days showed better growth performance and higher trimmed meat yield than 20 and 40 days supplementation.

Supplementing fructose-based block supplements to forage-fed cattle increases capacity for lactic acid metabolism

Acidosis is one of the more important maladies afflicting cattle fed significant amounts of grain and has enormous economic impact for feedlots, dairies, and producers of seed stock. The highest incidence of acidosis occurs when animals are being transitioned from high-roughage diets to diets containing high levels of concentrates. When grain-based diets are consumed in excess, consumed too quickly, or fed without proper adaptation, digestive end products (organic acids) can accumulate within the rumen, resulting in acidosis. Lactic acid is one of the key organic compounds that accumulates under these conditions. Coupled with the animal's limited ability to metabolize lactate, accumulation of lactic acid in the rumen lowers ruminal pH and subsequently depresses feed intake. One means of preventing acidosis is to directly populate the rumen with lactate-utilizing bacteria. Alternatively, exposure to low levels of lactate (i.e., levels insufficient to harm the animal) may stimulate development of a population of lactate-utilizing bacteria. The objective of our study was to determine if supplementing low-moisture blocks made of high fructose corn syrup could increase ruminal lactate concentrations and subsequently stimulate growth of lactate-metabolizing bacteria. If successful, this could prove useful for adapting forage-fed cattle to grain-based diets.

Diet Composition Affects Surgery-Associated Weight Loss in Rats with a Compromised Alimentary Tract

Esophageal adenocarcinoma (EAC) is the fastest growing cancer in terms of incidence and has a high mortality rate. The animal model to study EAC uses esophagoduodenal anastomosis (EDA) to induce mixed-reflux (bile/acid) causing esophagitis, Barrett's esophagus, and EAC sequence within 6 mo. However, the lack of fully functional stomach in these rats leads to the development of malnutrition. We have assessed the ability of a chemically pure, purified ingredient diet (AIN-93M) to reduce surgery-associated malnutrition in rats that have undergone the EDA-surgery. Animals were either sham- (SH) or EDA-operated and fed either a grain-based rodent diet (RD) (SH-RD, n=3; EDA-RD, n=10) or a purified diet (PD) (SH-PD, n=4; EDA-PD, n=11). The animals were weighed periodically for assessment of weight gain and euthanized at the end of 24 wk to measure esophageal tumor incidence. Animals that underwent sham surgery continued to gain weight throughout the study period and no tumors were detected. The EDA-operated animals had significantly lower weight gain compared with sham animals. There was no significant difference in weight gain among EDA animals fed two different types of diets until 9 wk after the surgery. After 9 wk, EDA-RD continued to lose weight significantly, whereas the weight loss leveled in EDA-PD (P<0.001). At termination, neither tissue histopathology nor tumor incidence was significantly different between the groups. These results show that compared with a natural ingredient diet, a purified ingredient diet can reduce surgery-associated weight loss in rats with a compromised alimentary tract. This reduction in malnutrition has the potential to reduce the confounding effects of weight loss on future animal studies reported.

Effects of yellow grease or soybean oil on performance, nutrient digestibility and carcass characteristics of finishing Awassi lambs

Twenty-three male Awassi lambs (initial body weight; BW = 18.5 ± 1.72 kg) were individually housed to study effects of using yellow grease (restaurant fat) on lamb performance, nutrient digestibilities and carcass characteristics, and to compare such effects with soybean oil (SO). Lambs were randomly assigned to one of three dietary treatments: no added fat (control; CTL, n = 7), 32 g/kg of yellow grease (YG, n = 8), or 32 g/kg of SO (SO, n = 8) in barley grain-based diets. All diets were formulated to be isonitrogenous, iso-energetic, and to meet all nutrient requirements for finishing lambs. Dietary treatments did not affect intake and digestibility of dry matter, organic matter, crude protein, neutral detergent fiber, or N retention. However, intake and digestibility of ether extract were higher ( P<0.05) by YG or SO diets. Lambs fed the YG or SO diets grew faster ( P<0.01) and were heavier ( P<0.01) than their control counter parts at the completion of the study. Additionally, lambs fed the YG or SO diets had heavier ( P<0.05) carcass weights than those offered the control diet. There were no substantial effects on carcass measurements or leg and loin composition, except for tissue depth and rib fat thickness which was higher for lambs offered the YG or SO diets. No histopathological changes occurred in liver, heart and kidneys due to treatments. Under the conditions of the study, dietary restaurant fat improved lamb performance with no detrimental effects on nutrient digestibilities or meat quality, and results were comparable to using soybean oil.

Development of the Black Soldier Fly (Diptera: Stratiomyidae) in Relation to Temperature: Table 1.

The black soldier fly, Hermetia illucens L., was reared on a grain-based diet at 27, 30, and 36 degrees C. Survival of 4- to 6-d-old larvae to adults averaged 74-97% at 27 and 30 degrees C but was only 0.1% at 36 degrees C. Flies required a mean of approximately 4 d (11%) longer to complete larval and pupal development at 27 degrees C than at 30 degrees C. At 27 and 30 degrees C, females weighed an average of 17-19% more than males but required an average of 0.6-0.8 d (3.0-4.3%) longer to complete larval development. At both temperatures, adult females lived an average of approximately 3.5 d less than adult males. The duration of larval development was a significant predictor of adult longevity. Temperature differences of even 3 degrees C produce significant fitness tradeoffs for males and females, influencing life history attributes and having practical applications for forensic entomology.

Diet composition affects the development of reflux‐induced esophageal adenocarcinoma in male SD rats

Esophageal adenocarcinoma (EAC) is the fastest growing incident cancer and has one of the highest mortality rate among all human cancers. The induction of mixed bile/acid reflux in rats by using esophagoduodenal anastomosis (EDA) causes reflux esophagitis and development of EAC within 6 months. In this study, we evaluated whether composition of the diet affects the development of reflux‐induced EAC. Male SD rats were either sham (SH)‐ or EDA‐operated and fed either a grain‐based rodent diet (RD) (SH‐RD, n=3; EDA‐RD, n=10) or a purified AIN‐93M diet (PD) (SH‐PD, n=4; EDA‐PD, n=11). They were weighed periodically and euthanized at the end of 24 weeks to measure esophageal tumors. All rats that underwent sham surgery continued to gain weight throughout the study period and no tumors were detected. Compared to sham animals, animals that underwent EDA‐surgery had significantly lower weight gain. There was no significant difference in weight gain among EDA animals fed 2 different types of diets until 9 weeks after the surgery. After 9 weeks, EDA‐RD continued to lose weight significantly, whereas the weight loss leveled in EDA‐PD (p&lt;0.001). However at 24 weeks, the tumor incidence was different but not statistically significant between the groups (4/10 in EDA‐RD (40%) versus 3/11 in EDA‐PD (27%)). These results suggest that the composition of the diet may affect weight gain and carcinogenesis in this model.

Estimation of the optimum ratio of standardized ileal digestible isoleucine to lysine for eight- to twenty-five-kilogram pigs in diets containing spray-dried blood cells or corn gluten feed as a protein source

Two growth assays and 1 N balance trial were conducted to determine the standardized ileal digestible (SID) Ile:Lys ratio in 8- to 25-kg pigs using spray-dried blood cells or corn gluten feed as a protein source. In Exp. 1, 48 individually penned pigs (initial BW = 7.7 kg) were used in a 6-point SID Ile titration study (analyzed SID Ile of 0.36, 0.43, 0.50, 0.57, 0.64, and 0.72%) by addition of graded levels of L-Ile. The basal diet contained 1.00% SID Lys, 18.4% CP, and 13.6 MJ of ME/kg. Diets were based on wheat, barley, corn, and 7.5% spray-dried blood cells as a protein source. Dietary SID Leu and Val levels were 1.61 and 1.02%, respectively. For the 35-d period, ADG, ADFI, and G:F increased linearly (P < 0.01) and quadratically (P < 0.04) with increasing SID Ile:Lys. Estimates of optimal SID Ile:Lys ratios were 59% for ADG and ADFI. In Exp. 2, 24 N balances were conducted using the Exp. 1 diets (12 pigs; individually penned; average BW = 11.5 kg). Pigs were fed 3 times daily with an amount equal to 1.0 MJ of ME/kg of BW(0.75). Preparation and collection periods (7 d each) were repeated after rearranging the animals to treatments. Increasing the dietary SID Ile:Lys ratio increased N retention linearly (P < 0.01), and N utilization linearly (P < 0.01) and quadratically (P < 0.01). An optimal SID Ile:Lys ratio of 54% was estimated for N retention. In Exp. 3, 48 individually penned pigs (initial BW = 8.0 kg) were fed grain-based diets in a 6-point SID Ile titration (analyzed SID Ile of 0.35, 0.41, 0.49, 0.56, 0.62, and 0.69%). Dietary SID Ile was increased by graded addition of L-Ile. The basal diet contained 0.97% SID Lys, 16.8% CP, and 13.6 MJ of ME/kg. In contrast to Exp. 1 and 2, spray-dried blood cells were excluded and corn gluten feed was used as a protein source. Dietary SID Leu and Val were set to 1.05 and 0.66%. For the 42-d period, ADG, ADFI, and G:F increased linearly (P < 0.01) and quadratically (P < 0.01) with increasing SID Ile:Lys. Estimated optimal SID Ile:Lys ratios were 54, 54, and 49 for ADG, ADFI, and G:F, respectively. These experiments suggest that the optimal SID Ile:Lys ratio depends on diet composition. In Exp. 1, AA imbalances because of increased Leu contents may have led to increased Ile nutritional needs. For ADG and ADFI, an optimum SID Ile:Lys ratio of 54% was estimated for 8- to 25-kg pigs in diets without Leu excess.