Effect of hay with or without concentrate or pellets on growth performance and meat quality of Ujimqin lambs on the Inner Mongolian Plateau

This study aimed to evaluate growth performance and meat quality of Ujimqin lambs fed native grass hay without or with concentrate (HC) or pellets. Ninety non-castrated 6-month-old male lambs of good health and similar body weight (26.83 ± 0.26 kg) were randomly divided into three groups (five lambs per cage). The average daily gain and intake of the pellets and HC groups were significantly greater (p < .05) than those in the hay group. The carcass weight, net meat mass, loin eye area, and backfat thickness were significantly greater (p < .05) in the HC groups. The intramuscular fat was significantly greater (p < .05) in the pellets and HC groups, while the shear force was significantly decreased (p < .05) in pellets and HC groups. The C16:0, C18:0, C18:1n9c, and C18:2n6 contents were significantly greater (p < .05) in the HC and pellet groups, while the C18:3n3 content was significantly greater (p < .05) in the hay group. Collectively, the present study suggested that feeding native grass hay with concentrate or pellets improved the growth in lambs.     

The effect of grain species, processing and time of feeding on the efficiency of feed utilization and microbial protein synthesis in sheep

This study investigated the effect of cereal grain species (sorghum, wheat, oats and barley), extent of processing (cracked barley, finely ground barley, and wet whole barley) and time of feeding (barley grain mixed with ryegrass hay or fed 2 h before hay was fed), on whole tract dry matter digestibility (WTDMD), and microbial protein synthesis (MPS), as a supplement to ryegrass hay when fed to rumen-cannulated sheep.Expected dry matter digestibility (EDMD) in mixtures of cereal grain and ryegrass hay was calculated by interpolation between in vitro dry matter digestibility (DMD) of each grain and the ryegrass hay. These were compared with measured actual WTDMD to detect positive or negative associative effects. Among grain species, the percentage difference in digestibility between actual WTDMD and EDMD was negative at − 6.6% units for wheat but positive at + 2.3%, + 4.3% and + 5.7% units for sorghum, oats, cracked or finely ground barley, respectively.As expected, the supplementation of sheep fed ryegrass hay with different sources of carbohydrates increased urinary allantoin output (as an indicator of MPS) when compared to sheep fed ryegrass hay alone. The concentration of urinary allantoin was significantly higher in sheep supplemented with sorghum (1916 mg/sheep/day) than wheat, oats or cracked barley ([mean ± S.E.M.] 1451 ± 24 mg/sheep/day) grain. There was a significantly higher urinary allantoin concentration in sheep fed cracked barley compared to finely ground barley or wet whole barley (1479 vs. 1095 vs. 1031 mg/sheep/day, respectively). There was no significant (P > 0.05) difference in urinary allantoin output, expressed as output/kg DM intake, when cracked barley was mixed and fed with the hay or fed 2 h before hay. However, in terms of total output of allantoin this was significantly higher (P < 0.05) (1479 vs. 1209 mg/sheep/day).In sacco degradability characteristics of organic matter and nitrogen for sorghum, oats, wheat, barley at different levels of processing and for ryegrass hay were also measured in the rumen of cannulated sheep.Among grain species, wheat had the highest effective organic matter degradability in the rumen (78.1%) while sorghum had the lowest. The effective degradability of protein of finely ground barley in the rumen was found to be higher than cracked barley or wet whole barley.Wheat grain, being highly degradable in the rumen, had a negative effect on WTDMD. In contrast, sorghum grain, being more slowly degradable in the rumen, would be expected to provide a substantially increased supply of energy to microbes over time in the rumen for MPS.Both cracked barley and finely ground barley also had a positive associative effect on WTDMD when fed with ryegrass increasing it by 5.7% units. The MPS was significantly higher (P < 0.05) in sheep fed cracked barley compared to finely ground barley or wet whole barley. This supports the hypothesis that slowly degrading carbohydrate sources synchronise more closely with available N from degradation of forage in the rumen.     

Rumen fermentation pattern of dairy heifers fed restricted amounts of low, medium, and high concentrate diets without and with yeast culture

Restricted feeding and high concentrate diets are potential strategies for growing dairy heifers. Ruminal manipulation with additives such as Saccharomyces cerevisiae yeast culture (YC) has been shown to alter digestibility when added to this type of diet. An experiment was conducted to investigate the ruminal fermentation and in situ digestibility of diets with 3 different levels of forage to concentrate (F:C) fed at restricted intake without and with YC addition. Three cannulated post-pubertal Holstein heifers (age 18.0 ± 1.2 months; body weight 449.6 ± 19.7 kg) were fed diets consisting of corn silage as the sole forage source in a 3 period (35-day) Latin square design. Heifers were fed diets for 21 days with no YC addition, followed by 14 days where YC was added to the diet (1 g/kg as fed basis). Low (LC), medium (MC), and high (HC) concentrate diets (20, 40, and 60% concentrate) were fed once daily on a restricted basis to provide 0.22 Mcal ME/kg empty BW^0.75. Rumen fluid was sampled on days 18 and 32 of each period, and rumen contents were evacuated on days 21 and 35 of each period. An in situ study was done on days 14 to 17 and on days 28 to 31. Mean ruminal pH was not different between dietary treatments and no YC effect was detected. Mean total volatile fatty acids (VFA) and ruminal ammonia-nitrogen (NH₃-N) concentration was also not different among diets with different F:C. Molar proportions of acetate were decreased, and propionate were increased; while the acetate-to-propionate ratio was decreased as the concentrate level increased from LC to HC. Total VFA, propionate, and acetate as well as isoacids concentration increased, yet NH₃-N concentration decreased with YC addition in all diets. From these results we conclude that feeding HC diets in restricted amounts had minimal effects on rumen fermentation rate between different F:C diets. The addition of YC modified NH₃-N and volatile fatty acid concentrations in the rumen in all 3 diets in this study, presumably through alterations in end-product production and utilization.     

Factors Affecting the Glucose Response to Insulin Injection in Mares: Epinephrine, Short- and Long-Term Prior Feed Intake, Cinnamon Extract, and Omega-3 Fatty Acid Supplementation

Five experiments were conducted with mares to better define factors that might affect the assessment of insulin sensitivity via direct insulin injection, and to then apply this method of assessing insulin sensitivity to trials which tested two potential supplements for improving poor insulin sensitivity in horses. The experiments assessed the effects of the following: (1) previous administration of epinephrine, (2) overnight feed deprivation versus hay or pasture consumption, (3) 10-day acclimatization to hay in a dry lot versus pasture grazing, (4) cinnamon extract supplementation, and (5) fish oil supplementation on insulin sensitivity. Mares of known high and low insulin sensitivities were used in the first three experiments, whereas mares with low insulin sensitivities were used in the supplement trials. Epinephrine administration increased blood glucose concentrations (P < .05) and prevented the insulin-induced decrease in blood glucose concentrations in both sensitive and insensitive mares. Overnight feed deprivation decreased (P < .06) insulin sensitivity relative to overnight ad libitum access to hay, and both regimens resulted in reduced insulin sensitivity relative to overnight pasture availability; sensitive and insensitive mares responded similarly except when kept on pasture (P = .0854). Ten days of hay consumption in a dry lot reduced (P < .05) insulin sensitivity in insensitive mares, but not in sensitive mares, relative to pasture grazing. Supplementation with cinnamon extract or fish oil had no effect on insulin sensitivity of mares with known low insulin sensitivity under the conditions of these experiments.     

Matua bromegrass hay for mares in gestation and lactation

Matua bromegrass hay (Bromus willdenowii Kunth) is a high quality forage, but its value for mares during gestation and lactation is not well known. Intake, rate of passage, performance, and reproduction by gestating and lactating Quarter Horse mares fed the hay was investigated. In this experiment, 12, 2- to 12-yr-old gravid mares (mean BW = 553 kg, SD = 36) were fed Matua hay (CP = 11.5%) or alfalfa hay (Medicago sativa L.) (CP = 15.4%) for variable days prepartum (mean 59.9 d; SD = 23.5) and for 70 d postpartum. Matua and alfalfa hay were fed as the roughage portion of the diet with a grain supplement. Mares, blocked by age, expected date of foaling, and BW, were assigned randomly within blocks to treatments (six mares per treatment). Forage type did not affect intake, gestation length, birth weight, number of foals, foal weight gain, day of first postpartum ovulation, cycles per conception, or pregnancy rate at 70 d. On d 1, milk from mares fed alfalfa hay contained less (P < 0.03) CP than milk from mares fed Matua hay. Milk CP decreased (P < 0.01) in all mares over time. In a separate experiment, voluntary intake and rate of passage of Matua (CP = 15.5%), alfalfa (CP = 24.9%), and Timothy (Phleum pratense L.) (CP = 4.1%) hays were determined in nine 2-yr-old pregnant mares (mean BW = 447 kg; SD = 21). Diets were 100% forage. Timothy hay did not meet CP requirements for mares. Voluntary intake of alfalfa hay was higher (P < 0.01) than Matua hay. Intake of Timothy hay was lower (P < 0.01) than the mean of alfalfa and Matua hay. Rate of passage offorage was measured by passage of Cr-mordanted fiber. Passage rate and retention time did not differ between Matua and alfalfa hay; however, the retention times of Matua and alfalfa hays were shorter (P < 0.01) than for Timothy hay. Our results indicate that Matua hay is a forage that can be used safely for mares during gestation and early lactation and for their young foals.     

Dietary concentrate level affects the feed sorting behaviour of lambs

The objective of this study was to evaluate the effect of forage concentration on sorting, nutrient intake and feeding behaviour of growing lambs. Twelve weaned lambs were exposed, in a crossover design with 7‐day periods, to each of two treatment diets: (i) lower‐concentrate diet (LC; 40.0% concentrate) and (ii) a higher‐concentrate diet (HC; 60.0% concentrate). Alfalfa hay was used as forage source. Sorting was determined by subjecting fresh feed and ort samples to particle separation and expressing the actual intake of each particle fraction as a percentage of the predicted intake of that fraction. Lambs sorted against long particles (>19 mm) on both treatments. On the LC diet, lambs sorted for medium particles, whereas animals fed the HC diet did not sort for or against medium particles. Lambs sorted for fine particles (<1.18 mm) on both treatments (p < .05). The extent of sorting for the fine particles was greater on the LC diet compared with the HC diet (p < .05). Dry matter intake was increased by increasing the concentrate content of the diet. Intake per visit and eating rate increased, and total chewing time was decreased in lambs fed HC diet. In conclusion, lambs sorted most against the longest particles and for the fine particles. Furthermore, feed sorting behaviour is affected by the forage level, and lambs sorted more for the fine particles in the LC diet.     

Effect of replacing barley with rice bran in finishing diet on productive performance and carcass characteristics of Afshari lambs

Thirty-five male Afshari lambs (3.5 months old), with an average weight of 35 kg were randomly assigned to one of five experimental treatments relating to optimal replacement level of rice bran in lamb finishing diets. The lambs were fed a milled concentrate (3 mm screen) diet supplemented with 15% (DM basis) chopped (5 cm length) lucerne hay and chopped (5 cm length) maize silage or wet (80% moisture) sugar beet pulp. Barley grain in the lambs’ diets was replaced by rice bran at either 0, 15, 30, 45 or 60% of the concentrate mixture on a dry matter basis. Results show that lambs fed 45 and 60% rice bran treatments weighed significantly less than those fed with 15 and 30% and control group (P < 0.05). Average daily gain in lambs fed with concentrate mixtures containing 45 and 60% rice bran were 33 and 47% lower than control, respectively (P < 0.05). Lambs that received diets containing 45 and 60% rice bran, had lower feed intake (P < 0.05) than other groups. Using rice bran in the finishing diet had no significant effect on dressing percentage, tail percentage, abdominal fat and visceral organ weights. These results suggest that barley can be replaced with rice bran up to 30% in the finishing diets of lambs without any adverse effect on lamb performance.     

Effect of dietary concentrate content on feed intake,feed efficiency,and meat quality of Holstein steers fattened in a hot environment

The objective of this study was to investigate the effect of feeding high and low concentrate diets on feed intake and feed efficiency, the morphological characteristics of the rumen papillae, and meat quality of Holstein steers fattened under hot climate conditions in Oman. Ten male Holstein calves, of 5 months of age, were selected for the experiment. The animals were fed concentrate and Rhodes grass hay and were divided into two groups of high concentrate (HC, n = 5) and low concentrate diets (LC, n = 5), in which their feed intake, weight gain, and feed efficiency were evaluated across three growing periods. Feed intake and efficiency and average daily gain (ADG) of the HC group were significantly greater than for the LC group and were affected by the diet (p < .01) and the period (p < .001). Across the fattening periods, ADG declined in both groups, with ADG improved by 35% for steers on the HC diet compared to steers on the LC diet. Carcass meat quality was not affected significantly by the dietary concentrate level. In conclusion, our results can be used to make improvements in feed efficiency of Holstein steers under hot climate conditions.     

Effects of the inclusion of yeast culture (Saccharomyces cerevisiae plus growth medium) in the diet of dairy cows on milk yield and forage degradation and fermentation patterns in the rumen of steers

The effects of including yeast culture (YC; Saccharomyces cerevisae plus growth medium; 5 x 10(9) organisms/g) in diets for ruminants was examined in two experiments. In Exp. 1, 32 multiparous Friesian dairy cows were fed between wk 7 to 12 of lactation one of four completely mixed diets based on either hay or straw plus rolled barley (mixed to give concentrate:forage ratios of either 50:50 or 60:40, respectively) with or without 10 g YC/d in a 2(3) factorial design. Supplementation with YC increased DM intake of the cows by a mean of 1.2 kg/d (P less than or equal to .062) and increased milk yield by 1.4 liters/d (corrected to 4% butterfat; P less than or equal to .05). There was an interaction (P less than .05) between diet composition and YC addition; effects of YC were greatest in diets containing 60:40 (concentrate:forage) ratio. In Exp. 2, three steers were fed a diet of 50% hay and 50% rolled barley (DM basis). Hay was available for the major part of the day but barley was fed in two meals/d. Addition of YC to the diet increased (P less than .05) ruminal pH for 4 h after the barley meal. This elevation in pH probably was due to a reduction (P less than or equal to .01) in the concentration of L-lactate in the ruminal liquor of steers given YC (1.43 vs 3.55 mM; P less than or equal to .01). Peak ruminal L-lactate concentration (7.75 mM) in the controls coincided with time of minimum pH values (2 h after the meal of barley); this peak was absent in steers given YC. YC had no effect on the concentration of VFA in ruminal liquor, but the ratio of acetate to propionate was reduced (P less than or equal to .01) from 3.3:1 to 2.8:1 in steers given YC. The extent of DM degradation of hay incubated in the rumen of steers fed the hay and rolled barley diet was increased (P less than .05) in the presence of YC at 12 h of incubation, but degradation was similar in all treatment groups after 24 h of incubation. Presence of yeast culture in the rumen had effects on ruminal stoichiometry. An increased rate of forage degradation may have increased forage intake and productivity of these dairy cows.     

Hormonal patterns in normal and hyperleptinemic mares in response to three common feeding-housing regimens

We previously reported that a rise in plasma leptin concentrations followed the rise in insulin and glucose in meal-fed horses, whereas horses maintained on pasture had little fluctuations in hormonal patterns. We have also described a hyperleptinemic-hyperinsulinemic condition that occurs in about 30% of our light horse mares of high body condition maintained on pasture. The present experiment was designed to 1) study the effect of 3 common feeding-housing regimens on leptin and other metabolic hormones in mares and 2) determine whether the hyperleptinemic condition interacted with these regimens. Six light horse mares with high body condition (average score = 7) were assigned to 2 simultaneous 3 x 3 Latin squares, 1 with normal mares (leptin = 0.1 to 6 ng/mL) and 1 with mares displaying hyperleptinemia (>10 ng/mL). Three feeding-housing regimens were compared: ad libitum pasture, ad libitum native grass hay in an outdoor paddock, and single morning feedings of a pelleted concentrate and hay at 0700 in a barn. Five days of acclimation to the feeding regimens were followed by a 36-h period of hourly blood collection to characterize the hormonal characteristics. Leptin concentrations were elevated (P < 0.001) in mares predetermined to be hyperleptinemic compared with normal mares, regardless of the feeding regimen. Leptin was greatest (P < 0.01) in mares on pasture and least in mares fed hay. Variations over time (P < 0.01) were present for all hormones and metabolites studied. Glucose and insulin concentrations were greatest (P < 0.01) in mares on pasture, with meal-fed mares exhibiting an immediate rise in plasma concentrations of both after feeding. Mares on hay had low and constant concentrations of glucose, insulin, and leptin, with no apparent fluctuations. Cortisol, prolactin, and IGF-I did not differ with leptin status, whereas GH differed due to feeding-housing regimen (P < 0.02); there was also an interaction of leptin status and feeding-housing regimen for GH concentrations (P = 0.094). It was concluded that 1) estimates of hormonal secretion in horses based on frequent sampling, depending upon the hormone in question, can be profoundly affected by the feeding-housing regimens, and 2) the hyperleptinemic condition persists under differing conditions of feeding-housing.     

Effect of cereal straw and alfalfa hay diet on amino acid profile of gastrointestinal digesta in lactating dairy cows

This study was conducted to evaluate the effects of replacing alfalfa hay with rice straw (RS) or corn stover (CS) on amino acid (AA) profiles of gastrointestinal digesta in lactating cows. Eighteen lactating dairy cows were randomly assigned to one of three groups (n = 6) and fed identical concentrate and corn silage with different forages on dry matter basis: (i) 23% alfalfa hay and 7% Chinese wild rye hay (AH); (ii) 30% CS; and (iii) 30% RS. After the 14‐week feeding, a total of 18 cows were slaughtered to collect digesta from four representative organs, including rumen, omasum, duodenum and jejunum. The AA profiles of ruminal microbial fraction were similar among the treatments, except for greater Arg in cows fed RS than in cows fed AH or CS. Most of the analysed AA changed under different diets. Significant differences were found among the microbial fraction, rumen fluid and rumen digesta, with greater essential AA in digesta than in microbial fraction or rumen fluid and greater essential AA in microbial fraction than rumen fluid. Significant differences in individual AA profiles of digesta and relevant fluid were found across the four representative digestive tract parts, including rumen, omasum, duodenum and jejunum, showing much lower Leu proportion in CS and RS than in AH in duodenal fluid. In summary, ruminal microbes may prefer using essential AA, rather than non‐essential AA. The AA profile of ruminal microbes was constant except for Arg. The AA composition of digesta across the four digestive tracts changed dramatically, which indicated differences in the ability and efficiency of AA absorption. The lower duodenum absorbable Leu proportion in cows fed CS or RS indicated the shortage of Leu in CS or RS diets, which might also restrict the balanced AA absorption.     

复合抗菌肽对山羊瘤胃发酵和酶活性的影响

本试验旨在探讨复合抗菌肽对饲喂不同精料饲粮山羊瘤胃发酵和酶活性的影响。选取18只4月龄雄性山羊,随机分3组,每组6只。对照组(Ⅰ组)、高精料组(Ⅱ组)、高精料抗菌肽组(Ⅲ组)分别饲喂300、600和600 g/(只·d)精料,同时Ⅲ组在精料中添加3.0 g/(只·d)复合抗菌肽。试验期为60 d。结果表明:1)与Ⅰ组相比,Ⅱ组瘤胃液乙酸、总挥发性脂肪酸(T-VFA)、甲烷(CH4)、氨态氮(NH3-N)、尿素氮、微生物蛋白(MCP)浓度与(乙酸+丁酸)/丙酸及木聚糖酶、脂肪酶活性极显著或显著增加(P0.01或P0.05),羧甲基纤维素酶(CMCase)、β-葡萄糖苷酶和淀粉酶活性极显著或显著降低(P0.01或P0.05),丙酸、丁酸浓度及果胶酶、中性蛋白酶活性无显著变化(P0.05)。2)与Ⅱ组相比,Ⅲ组瘤胃液丙酸、丁酸、NH3-N浓度及CMCase、果胶酶、中性蛋白酶及脂肪酶活性无显著变化(P0.05),乙酸、T-VFA、CH4、尿素氮浓度与(乙酸+丁酸)/丙酸及木聚糖酶活性极显著或显著降低(P0.01或P0.05),MCP浓度及β-葡萄糖苷酶、淀粉酶活性极显著或显著增加(P0.01或P0.05)。由此说明,复合抗菌肽可调节山羊瘤胃发酵模式,提高饲料利用率,是理想的饲料添加剂。     

Lactation and reproductive performance of mares fed added dietary fat during late gestation and early lactation

Eighteen pregnant mares were randomly allotted to one of two treatment groups. The control group was fed a conventional concentrate and the fat group was fed a concentrate containing 5% feed-grade rendered fat. Both concentrates had the same nutrient:calorie ratio and were fed in amounts required to maintain zero change in percent body fat of the mares. During the study, which began 60 d prior to expected foaling date and ended 60 d postpartum, mares were monitored for feed intake, body weight, rump fat thickness, ration digestibility, plasma glucose and lipid concentrations, milk composition and reproductive efficiency. Birth weight, growth rate, and plasma glucose and lipid concentrations were also measured in foals. Mares fed fat consumed less concentrate (P<.09 during the last 60 d of gestation but consumed similar amounts of concentrate over 60 d of lactation. Protein and ether extract digestion was higher (P<.05 and P<.09, respectively) in the mares fed fat during the postpartum period. Dietary treatment had no influence on plasma glucose or lipid concentrations of the mares or plasma glucose concentrations of their foals, but foals whose dams were fed fat had higher plasma lipid concentrations at birth (P<.01), d 10 and d 30 (P<.05). Percent fat was higher in milk samples from mares fed fat at d 10 (P<.09, 1.23 vs .99%) and d 60 (P<.01, .72 vs .43%) of lactation. Reproductive performance was not significantly different between treatment groups, however there was a trend for a shorter postpartum interval and fewer cycles per pregnancy in the mares fed added fat. Foals from both groups were of similar size and weight at birth and had similar weight gains over 60 d, however, foals nursing mares fed fat tended to gain more weight in the first week of life (1.85 vs 1.56 kg/d) and have more rump fat at d 60 (.53 vs .44 cm) than foals nursing control mares.     

Comparison of Nutrient Digestibility Between Adult and Aged Horses

There is little published work comparing digestibility in healthy adult versus healthy aged horses. Researchers hypothesized that there would be no differences in macronutrient digestibility between eight adult (5–12 years) and nine aged (19–28 years) horses fed three diets in a Latin square design. Seventeen stock-type mares were randomly assigned for a 5-week period to one of three diets: hay only (HAY), hay plus a starch- and sugar-rich concentrate (CHO), or hay plus a fat- (oil) and fiber-rich concentrate (FF). Each diet period comprised 3 weeks of outdoor group drylot feeding, 2 weeks of indoor stalled individual feeding, followed by a 72-hour digestibility trial including total urine and fecal collection. Feed, fecal, and/or urine samples were analyzed to determine dry matter, crude protein, fat, energy, calcium, and phosphorus apparent retention as well as apparent digestibility. Neutral detergent fiber digestibility was also determined. Mean body weight was lower in aged than in adult horses (455 ± 12 kg vs. 500 ± 13 kg; P = .02), but body condition score (BCS) did not differ between groups (aged horses, 4.8 ± 0.2 BCS and adult horses, 5.1 ± 0.2 BCS; P = .20). No age differences in digestibility, apparent digestibility, or apparent retention were seen for any of the variables measured. Based on the results of this study, total tract macronutrient digestibility appears to be similar between healthy adult and aged horses.     

Feeding and microbial disorders in horses: Part 3—Effects of three hay:grain ratios on microbial profile and activities

Cecal and colonic fluid contents were collected from three ponies and analyzed to determine the effects of three hay:barley ratios on their microbial and biochemical characteristics. Three diets based on chopped meadow hay and rolled barley were tested in a 3×3 Latin square experiment: 100% hay (100:0, 114gDM/KgBW^0.75/day), 70% hay-30% barley (70:30, 69gDM/KgBW^0.75/day) and 50% hay-50% barley (50:50, 58gDM/KgBW^0.75/day). Enumeration of total anaerobic and aero-anaerobic bacteria, lactate-utilizing and cellulolytic bacteria, lactobacilli and streptococci, as well as pH, lactate and VFA concentrations, were determined after 14 days adaptation to the new diet. In the large intestine, the concentrations of total bacteria were higher with the diets containing barley than with the hay diet, whereas cellulolytic bacteria were depressed with the concentrate diets. As the proportion of barley increased, concentration of lactate-utilizing bacteria, lactobacilli and streptococci increased in the colon while it did not interfere significantly on these populations in the cecum. These changes of the microflora were associated with a significant decrease in intestinal pH and [(acetate+butyrate)/propionate] ratio, and a numerical increase of lactate concentration.     

Indigestion in young calves. IV. Lesions of ruminal papillae in young calves fed barley and barley plus hay.

Fiftysix calves, in 2 similar experiments, were given 1 of 4 diets including a high lactose milk replacer: ground barley (GB), ground barley plus coarse hay (GB + GH), coarse hay (CH) and the liquid diet only (NS) ; the 2 last diets were held as controls. The calves were on the experimental diet from 1–2 weeks of age until slaughtered at 7-8 weeks of age. As observed by stereo-microscopy, the ruminai papillae in calves fed on GB were thickened, mostly finger- or club-shaped and sometimes nodular; nodular papillae were always arranged on prominent mucosal folds. Scattered nodular papillae had white coats. For calves fed on GB + CH the papillae were mostly finger- or tongue-shaped. Histologically papillae in calves fed on GB had hyperplasia of secondary papillae and epithelial layers. Microabscesses associated with penetrating hairs were frequent, and some calves had dyskeratosis with infiltration of polymorphonuclear leucocytes at the apex of papillae, identified as the white coats. For calves given GB+CH, abscesses and apical dyskeratosis were absent and the hyperplasia of epithelial layers milder than in the case of the GB diet. An ameliorative effect of hay on papillary changes caused by barley is indicated.     

Efficacy of Medroxyprogesterone Acetate in Suppression of Estrus in Cycling Mares

The effects of compounded medroxyprogesterone acetate (MPA) on follicular activity and estrous behavior were evaluated. Eighteen cycling mares were assigned to one of three treatment groups. Mares in the MPA group (n = 6) were injected intramuscularly with 1,600 mg MPA (week 1), then 400 mg weekly for the next 5 weeks. Saline mares (n = 6) were injected intramuscularly weekly for 6 weeks. Altrenogest mares (n = 6) received 10 mL orally daily for 7 weeks. Mares were teased daily for 60 days and categorized as displaying estrous, diestrous, or neutral behavior. Transrectal ultrasound examinations were performed three times weekly, or daily when a 30-mm follicle was identified, until ovulation. Blood samples were harvested weekly for analysis of progesterone concentration and daily from days 14 to 23 for analysis of luteinizing hormone (LH) concentration. Mares treated with saline or MPA showed normal intervals of diestrus and estrus during the study. All altrenogest mares showed behavioral diestrus during treatment. All mares in the saline and MPA groups showed normal follicular development and ovulations. No altrenogest mares ovulated during treatment; four mares returned to estrus and resumed normal follicular development after treatment ceased. Progesterone analyses agreed with transrectal ultrasonographic ovarian activity for all mares. LH levels were lower for altrenogest-treated mares compared with MPA-treated and saline-treated mares during the treatment period. In conclusion, compounded MPA at dose rates and intervals used in this study was not effective in suppression of estrus, follicular development, or LH secretion in mares.     

Minimum length of the adaptation and collection period in digestibility trials with sheep fed ad libitum only forage or forage plus concentrate

Two in vivo digestibility trials with sheep were conducted to identify the minimum period length of feeding a new diet to obtain reproducible values of nutritional variables onward and the minimum length of collection period as to obtain maximal precision for each variable. Trial 1 was conducted with ten Polwarth male sheep (34 ± 5 kg body weight (BW)) throughout three 21‐day periods, in a completely randomized two‐way crossover design. The animals were divided into two groups (Group A and B, n = 5 per group) which were fed ad libitum with a sequence of the following diets throughout the periods: Group A: hay – hay plus concentrate – hay; Group B: hay plus concentrate – hay – hay plus concentrate. The concentrate was included in a proportion of 0.33 of the total diet. The intake, and the faecal and urinary excretion were measured daily throughout the experiment. For evaluating rumen fermentation variables, in Trial 2 four Santa Inês male sheep (65 ± 5 kg BW) fitted with ruminal cannula were used. The animals were randomly divided into two groups (n = 2 per group), and the trial was conducted through four 21 days experimental period, in a three‐way crossover design, using experimental diets and feeding management similar to Trial 1. The results indicated that, even though no clear or consistent steady‐state condition was identified for rumen fermentation or urinary excretion variables, the adaptation period for measuring OM digestibility in in vivo trials with sheep fed ad libitum where the diet shifts from one of only hay to another containing concentrate, or vice‐versa, should be at least 12 days long. Moreover, although no precision improvement was obtained by increasing the collection period above 1 day for measuring OM digestibility, the minimal length of collection period should be 4 days for measuring faecal excretion variables and 7 days for measuring urinary excretion variables.     

Response of lactating dairy cows to degree of steam‐flaked barley grain in low‐forage diets

This study was conducted to investigate the effects of processing method (grinding vs. steam flaking) and increasing densities of steam‐flaked barley grain on dry matter intake (DMI), rumen pH and fermentation characteristics, digestibility of dry matter in the total digestive tract (DDTT), and milk production of dairy cows. Eight multiparous mid‐lactation Holstein cows averaging 103 ± 24 DIM, 44.5 ± 4.7 kg milk/day and weighing 611 ± 43 kg at the start of the experiment were used in a replicated 4 × 4 Latin square design with 21‐day periods. Cows were fed diets consisting of (DM basis) 23.8% corn silage, 13.5% chopped alfalfa hay and 62.7% concentrate. The dietary treatments were either ground barley (GB) using a hammer mill or steam‐flaked barley (SFB) – varying density at 390, 340 or 290 g/l. Processing method (GB vs. SFB) did not affect DMI (23.6 kg/day on average), DDTT (71.0% on average), milk yield (43.4 kg/day on average), milk components, rumen pH and molar proportions of acetate, propionate, butyrate and sorting activity. Ruminal isovalerate concentration tended (p = 0.06) to be higher for cows fed GB than those fed SFB‐based diets. Decreasing the density of SFB from 390, 340 to 290 g/l tended to linearly increase DMI (p = 0.09), decrease total solids percentage of milk (p = 0.10) and linearly decreased milk urea nitrogen (12.8, 12.4 and 12.1 mg/dl; p = 0.04); also, the sorting index (SI) of the particles retained on the 19.0‐mm sieve without affecting the SI of the particles retained on 8.0‐mm, 1.18‐mm or passed through 1.18‐mm sieve (p = 0.05). These results indicated the limited effects of processing method (grinding vs. steam flaking) and densities of SFB (390, 290 or 290 g/l) on cows’ performance and feed utilization for dairy cows fed low‐forage diets. Therefore, both processing methods could be recommended under current feeding conditions of dairy cows.     

Effects of monensin, pyromellitic diimide and 2-bromoethanesulfonic acid on rumen fermentation in vitro

The effects of monensin, 2-bromoethanesulfonic acid (2-BES) and pyromellitic diimide (diimide) on gas and volatile fatty acid (VFA) production by the rumen microbiota were compared in mixed culture. Oat hay, a hay-concentrate mixture (48% hay, 43% concentrate) and a soluble carbohydrate mixture were used as substrates for microbial growth. The highest concentrations of diimide (10 ppm) and 2-BES (30 microM) decreased methanogenesis by 97 and 76%, respectively, while H2 accumulation was increased 30- and 20-fold, respectively. The effect of monensin on methanogenesis was less dramatic as 10 ppm decreased CH4 accumulation 16% and H2 did not accumulate. Diimide and 2-BES decreased the acetate:propionate ratio with the hay (P less than .05) and soluble carbohydrate mixture (P less than .025). The numbers of saccharolytic, cellulolytic and methanogenic bacteria from sheep fed a diet with diimide (60 ppm) did not differ significantly from sheep fed a control diet. Semicontinuous culture incubations indicated that the mixed rumen microbial population could adapt and degrade diimide after 24 h of incubation.