The nutritive value for sheep of quackgrass and timothy hays harvested at two stages of growth

Thirty-two wethers were used to compare the nutritive value of Climax timothy (Phleum pratense L.) and quackgrass (Agropyron repens L. Beauv.) harvested at two stages of maturity, joint and early heading, and fed as hay. Crude protein was higher for quackgrass than for timothy (P less than .01). As maturity advanced, CP decreased (P less than .01), but NDF and ADL increased (P less than .01). Dry matter intake was similar between species but decreased by 8% with increasing maturity (P less than .01). Intake of NDF (g/kg.75) was similar for all hays. With increasing plant maturity, apparent digestibility decreased, the effect being more pronounced for quackgrass. Apparent digestibilities of DM and energy were slightly higher (P less than .06) for timothy, and those of CP and hemicellulose were higher for quackgrass (P less than .01). Apparent digestibilities of NDF, ADF, ADL, crude fiber and cellulose were similar between species. Dry matter intake and digestibility were correlated negatively with the ADL/ADF ratio of the hay (r = -.99, P less than .01), whereas CP intake and CP digestibility were correlated with CP of the hay (r = .99, P less than .01). The Lucas test estimated true protein digestibility at 88.1% and metabolic fecal protein at 29.4 g per kg of DM intake. During the growth trial, DM intake was similar between hays, but ADG of sheep was lower (P less than .01) for those fed hays at early heading vs those receiving hays at the joint stage of maturity. The feed to gain ratio was slightly lower for hays at joint (P less than .08). Under the climatic conditions of the 1988 growing season, the nutritive value of quackgrass was similar to that of Climax timothy.     

Effect of exogenous fibrolytic enzyme on ruminal fermentation and digestibility of alfalfa and rye-grass hay fed to lambs

This experiment was carried out to study the effect of a directly fed exogenous fibrolytic enzyme on intake and digestion of DM, OM, protein, NDF, ADF, and hemicellulose of alfalfa and ryegrass hay by sheep. Four diets were randomly assigned to four ruminally cannulated lambs using a 4 x 4 Latin square design, repeated in time, with a factorial arrangement (2 x 2) of diets: 1) alfalfa hay; 2) alfalfa hay + exogenous fibrolytic enzymes (enzyme); 3) ryegrass hay; and 4) ryegrass hay + enzyme. Lambs consumed more DM and OM from alfalfa than from ryegrass hay (P < 0.001). The ADF intake was not different between the hays, but NDF intake was lower for alfalfa (P < 0.001). For both hays, the enzyme increased intake of DM (P < 0.01), as well as OM and CP (P < 0.05); however, NDF and ADF intake were not changed. Alfalfa hay had higher apparent digestibility of DM, OM, and CP (P < 0.001), but lower digestibility for NDF, ADF, and hemicellulose. The enzyme increased apparent digestibility of CP, hemicellulose (P < 0.05), and NDF (P < 0.10) for alfalfa. Also, for both hays, the enzyme improved N balance because lambs retained more N (P < 0.05). The enzyme increased (P < 0.05) total VFA concentration (3 and 6 h) for both hays. Results from this trial indicate that directly fed exogenous fibrolytic enzymes may change ruminal fermentation, intake, and digestibility of forages with different nutritive value.     

Potential of alfalfa as a source of calcium for calcium deficient horses

The potential of short-cutting cycle, high temperature-dried alfalfa as a source of calcium for horses was determined by means of a 4 x 4 Latin square digestibility trial using four thoroughbred horses (mean liveweight 531 kg). The four dietary treatments were timothy hay alone, 33 per cent alfalfa and 67 per cent timothy hay, 67 per cent alfalfa and 33 per cent timothy hay, and alfalfa alone. Significantly more calcium and magnesium were absorbed from the alfalfa than from the hay. Phosphorus absorption appeared to be unaffected by treatment. Alfalfa calcium was more available than timothy hay calcium (apparent absorption coefficients of 0.78 and 0.15, respectively) and there was less variation between individual horses in their ability to absorb calcium from alfalfa. Horses fed alfalfa had significantly higher creatinine clearance ratios for calcium (P less than 0.01) and magnesium (P less than 0.001) than horses fed hay, but the creatinine clearance ratio for phosphorus was lower in horses fed hay alone.     

Acceptability of Teff Hay by Horses

Teff (Eragrostis tef) is a productive warm season annual grass. Because teff is relatively new to the horse industry in the United States, horses unaccustomed to teff hay were used in two sets of two-choice preference tests comparing teff with alfalfa hay or teff with timothy hay. A second experiment used mature mares to compare voluntary dry matter intake (VDMI) of teff hay and timothy hay. In the two-choice preference tests, horses preferred alfalfa hay and timothy hay to teff hay (P < .05). Horses preferred teff hay that was cut at an earlier stage of maturity and had lower concentrations of neutral detergent fiber and acid detergent fiber than teff hay cut at a later stage of maturity. In the VDMI experiment, four mares were fed teff hay and four mares were fed timothy hay for 17 days. Both hays had been harvested in the head stage of maturity. VDMI was measured during the last 10 days and was not different between the two groups of horses (P > .05). It was concluded that horses that are unfamiliar with teff may discriminate against it when it is offered simultaneously with alfalfa or timothy; however, if not given a choice, horses will consume approximately the same amount of mature teff as mature timothy. Additional studies are needed to compare VDMI of early maturity teff hay with other common hays.     

Effect of method of applying fibrolytic enzymes or ammonia to Bermudagrass hay on feed intake, digestion, and growth of beef steers

This study examined how different methods of applying a fibrolytic enzyme or ammonia affect the nutritive value of Bermudagrass hay and the performance of beef cattle. Fifty Angus x Brangus crossbred steers (mean initial BW 244 +/- 26 kg) were individually fed for ad libitum intake of a 5-wk regrowth of a mixture of Florakirk and Tifton 44 Bermudagrass [Cynodon dactylon (L.) Pers] hay for 84 d with a concentrate supplement (77% soybean hull pellets, 23% cottonseed meal (DM basis) fed at 1% of BW daily. The Bermudagrass was conserved as hay without treatment (control), with NH(3) (30 g/kg of DM), or with a fibrolytic enzyme (16.5 g/t, air-dry basis) that was applied immediately after cutting (Ec), at baling (Eb), or at feeding. Chromic oxide was dosed to steers for 10 consecutive days, and fecal Cr concentrations from the last 5 d were used to estimate apparent total tract digestibility. In situ ruminal DM degradability was measured by incubating ground (4-mm) hay samples in duplicate in each of 2 ruminally cannulated cows having ad libitum access to Bermudagrass hay and 500 g/d of soybean meal. Unlike the enzyme treatment, ammoniation increased (P < 0.001) the CP concentration and reduced (P < 0.001) NDF, hemicellulose, and lignin concentrations of hay. Total DMI was greater (P < 0.05) for steers fed hays treated with Ec or NH(3) than for those fed control hays. All additive treatments increased (P < 0.05) DM digestibility, and NH(3), Ec, and Eb treatments also increased (P < 0.01) NDF digestibility. The initial and final BW, ADG, BCS, G:F, and hip height of the steers were not affected (P > 0.05) by treatment. The wash loss fractions in hays treated with Ec and Eb were lower than that in the control hay, but the potentially degradable fraction, total degradable fraction, and the effective degradability were increased (P < 0.01) by NH(3) treatment. Application at cutting was the most promising method of enzyme treatment, and this treatment was almost as effective as ammonia for enhancing forage quality.     

Voluntary intake, digestibility, and subsequent selection of Matua bromegrass, coastal bermudagrass, and alfalfa hays by yearling horses.

Matua bromegrass (Bromus willdenowii Kunth. cv. Grasslands Matua) was introduced in 1973, but little information exists concerning its potential as a hay for horses. Thus, voluntary intake and apparent digestibility of OM, CP, and fiber components of Matua by 18 Quarter Horse yearlings (mean initial BW 354 kg; SE 5.8) were compared with alfalfa (Medicago sativa L.) and coastal bermudagrass (Cynodon dactylon L.) as hays in a randomized block design. A 15-d adjustment period was followed by a 5-d collection period during which the hays were consumed ad libitum. Voluntary intake of DM was greater (P<.01) for alfalfa (10.9 kg/d) than for the mean of the grasses, and intake of Matua (10.0 kg/d) was greater (P<.001) than that of bermudagrass (7.4 kg/d). Apparent digestibility of OM was greater (P<.001) for alfalfa (74%) than for the mean of the grasses but did not differ between Matua (64%) and bermudagrass (60%). At the end of the digestion trial, each yearling was offered each of the three forage hays during an 11-d period to determine subsequent preference and effect of previous hay experience. Yearlings preferred alfalfa over the grass hays and generally selected more Matua than bermudagrass. All yearlings consumed less of the forage species to which they had been previously exposed compared with unadapted yearlings. The Matua hay fed in this trial was palatable and met most of the nutritional needs for yearling horses.     

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.     

Effect of protein source on nitrogen balance and plasma amino acids in exercising horses

Plasma AA in horses fed either an all-hay or a hay and grain diet in a traditional format have not been investigated. Eight horses were divided into 2 groups: a hay group fed only grass hay or a hay and a grain group (HG) fed in a crossover design for two 5-wk periods. After the first period, horses were fasted overnight, followed by feeding with blood sampling every hour for 6 h. A 4-d total fecal and urine collection to evaluate N balance followed. A 10-d washout period separated the 5-wk feeding periods, during which horses switched diets. The second period was also followed by fasting, feeding, blood sampling, and a 4-d collection period. Horses consumed 840 g of CP in the hay group and 865 g of CP in the HG group. Horses in the hay group had a 2.4 ± 2.4 g/d N balance, which was not different from 0 (P = 0.34), whereas horses in the HG group had 5.4 ± 2.4 g/d N balance, which was different from 0 (P = 0.045). Fecal N excretion was greater for the hay group compared with the HG group (hay = 51.1 ± 1.3 g/d and HG = 45.5 ± 1.3 g/d; P = 0.011), and urine N excretion was greater for the HG group compared with the hay group (hay = 79.3 ± 2.8 g/d and HG = 89.2 ± 2.8 g/d; P = 0.026). Plasma AA concentrations were greater in the HG group compared with the hay group for Met (P = 0.001), Lys (P = 0.001), Ile (P = 0.047), Arg (P < 0.001), Gln (P = 0.009), and Orn (P = 0.002). Plasma concentrations were less for the HG group compared with the hay group for Thr (P < 0.001) and Ala (P < 0.001). Plasma concentrations of urea were greater for the HG group compared with the hay group (P < 0.001), whereas 3-methyl-histidine concentrations were greater for the hay group compared with the HG group (P < 0.001). The effect of diet on the excretion of N via feces vs. urine in the hay and HG groups is typical. The early increases in the plasma concentrations of Met, Val, Ile, Leu, Phe, Lys, Arg, and Ala during the postfeeding phase are most likely due to increased foregut digestibility as well as a greater quality AA profile in the grain. The greater concentrations of Thr, Leu, and Val later in the postfeeding phase for the hay group most likely reflects slower digestion because of prolonged consumption time compared with the HG group. Improved N balance observed in the HG group supports the fact that the HG group had more available AA via the AA profile and foregut digestibility of the HG diet. Despite the fact that both groups consumed similar amounts of CP, the AA profile and availability affected N balance.     

A comparison between the nutritive value of short-cutting cycle, high temperature-dried alfalfa and timothy hay for horses.

The objective was to evaluate the nutritive value of short-cutting cycle, high temperature-dried (SCCHTD) alfalfa compared to timothy hay. This was achieved by carrying out 4 x 4 Latin Square digestibility trial using 4 Thoroughbred (one three-quarter Thoroughbred) horses (mean liveweight, 531 kg). The four dietary treatments were 0AA (timothy hay only), 33AA (0.33 alfalfa: 0.67 timothy hay), 67AA (0.67 alfalfa: 0.33 timothy hay) and 100AA (alfalfa only). Digestibility data were obtained by using acid-insoluble ash to estimate apparent digestibility coefficients of nutrients. Rate of passage of the feedstuff was determined using chromium-mordanted hay. Plasma triglyceride and cholesterol concentrations were estimated. The digestibilities of organic matter (0.63), energy (0.57) and crude protein (0.74) of the alfalfa were significantly (P less than 0.001) higher than those for the hay (0.45, 0.43 and 0.36 respectively). The fibre components of alfalfa and hay were digested to the same extent but the ether extract of alfalfa was less well digested. Alfalfa saponins had no consistently significant effects on plasma cholesterol and triglyceride values but may contribute to the negative digestibility of alfalfa ether extract. We conclude that SCCHTD alfalfa is of much higher nutritive value than timothy hay when fed to Thoroughbred horses.     

The effect of very low food intake on digestive physiology and forage digestibility in horses

Equid digestion is often conceptualized as a high‐throughput/low‐efficiency system, in particular compared with ruminants. It is commonly assumed that ruminants have an advantage when resources are limited; the effect of low food intake on digestive physiology of horses has, however, not been explored to our knowledge. We used four adult ponies [initial body mass (BM) 288 ± 65 kg] in two subsequent trials with grass hay‐only diets [in dry matter (DM): hay1, mid‐early cut, crude protein (CP) 10.5%, neutral detergent fibre (NDF) 67.6%; hay2, late cut, CP 5.8%, NDF 69.5%], each fed subsequently at four different dry matter intake (DMI) levels: ad libitum and at 75, 55 and 30 g/kg^0.75/day. We particularly expected digesta mean retention times (MRT) to increase, and hence fibre digestibility to increase, with decreasing DMI. Ponies maintained BM on the first, but lost BM and body condition on DMI55 and DMI30. MRTs were negatively correlated to DMI and ranged (for particles <2 mm) from 23/31 h (hay1/2) on the ad libitum to 38/48 h on DMI30. Digestibilities of DM, nutrients and fibre components decreased from DMI75 to DMI30; apparent digestibilities of organic matter and NDF (hay1/2) dropped from 47/43% and 42/37%, respectively, on the ad libitum DMI to 35/35% and 30/28% on DMI30. Additional differences evident between the two hays included a higher estimated ‘true’ protein digestibility for hay1 and finer faecal particles on hay2; there were no differences in faecal particle size between intake levels. The results suggest that below a certain food intake threshold, the major digestive constraint is not fermentation time but nutrient supply to gut bacteria. The threshold for such an effect probably varies between feeds and might differ between ruminants and equids.     

Effects of lactational status on forage intake, digestibility, and particulate passage rate of beef cows supplemented with soybean meal, wheat middlings, and corn and soybean meal

Sixteen mature, lactating (453 kg) and 16 nonlactating (487 kg) Hereford and Angus x Hereford cows were used to determine effects of different dietary supplements and lactational status on forage intake, digestibility, and particulate passage rate. Supplement treatments and amounts fed (kg/d) were as follows: control, 0; and equal daily amounts of CP from soybean meal (SBM), 1.36; wheat middlings (WM), 3.41; or a blend of corn and soybean meal (corn-SBM; 22% corn and 76% SBM), 3.41. Cows were fed supplements at 0800 and had ad libitum access to prairie hay (4.9% CP) in stalls from 0800 to 1100 and from 1300 to 1600 for three 17-d periods. Lactational status and supplement type did not interact (P greater than .50) for hay DMI, DM digestibility, or particulate passage rate. Cows fed SBM ate more hay DM (P less than .01) and had greater hay DM digestibility (P less than .01) than did cows in other treatment groups. Average hay DMI (kg/100 kg of BW) was 1.95, 2.16, 1.94, and 1.89, and hay DM digestibility was 52, 61, 55, and 53% for control, SBM, WM, and corn-SBM supplements, respectively. Total diet DM digestibility was increased by supplementation (P less than .01), but no differences (P greater than .18) were observed among supplements. Lactating cows ate more (P = .13) hay DM (2.11 vs 1.87 kg/100 kg of BW) and had greater (P less than .05) fecal output (4.6 vs 4.3 kg/d) than did nonlactating cows. Dry matter digestibility and particulate passage rate were not affected (P greater than .35) by lactational status.(ABSTRACT TRUNCATED AT 250 WORDS)     

Voluntary Intake of Four Hay Types by Horses

Alfalfa, teff, oat, and wheat hays were fed to eight mature horses to determine voluntary intake of each hay type. After a 2-week adaptation period during which each horse was offered all four hay types each day, a 4-week study was conducted in which two horses were offered each type of hay each week, usually at the rate of 2.2% of initial body weight. Refused feed was collected and weighed the last 5 days of each week to calculate voluntary intake. Horses consumed significantly more alfalfa hay than the other hays. Wheat and teff hays were consumed in significantly lower amounts than alfalfa, but significantly more than oat hay. Across the 5 days during which voluntary intake was measured each week, hay consumption increased each day, reaching levels significantly greater than day 1 by day 4, when measured as a percentage of body weight, and day 5 when measured as a percentage of feed offered. Only alfalfa hay, at the amount consumed, met 100% of nutrient requirements for digestible energy, crude protein, lysine, calcium, and phosphorus for horses in maintenance condition. Teff hay met all nutrient requirements except digestible energy. Neither wheat nor oat hays met 100% of any of these nutrient requirements. Alfalfa and teff hays averaged about 12% nonstructural carbohydrate content (NSC), whereas wheat and oats hays contained about 30% NSC. The lower NSC content of the alfalfa and teff hays makes these more suitable for horses with problems related to carbohydrate metabolism or for refeeding starving horses.     

Dry matter intake and digestion of alfalfa harvested at sunset and sunrise

The preference exhibited by animals in selecting one feed over another is important only if the preferred diet is consumed daily in larger quantities, digested to a greater extent, or both. Six alfalfa (Medicago sativa L.) hays were harvested in pairs at sunset (PM) and sunrise (AM) on consecutive days at three harvest dates. A previous study of these hays demonstrated differences in ruminant preference favoring PM harvests. This study evaluated the effects of time of cutting and harvest date on voluntary DMI and nutrient digestibility. The hays were field-cured, baled, and chopped before evaluation for intake and digestibility. Studies were conducted for sheep (Ovis aries), goats (Capra hircus), and cattle (Bos taurus). Goats, but not steers or sheep, demonstrated differences in nutrient digestibility between PM- and AM-cut hays. Goats consumed more PM than AM hay (2.97 vs. 2.83 kg/100 kg of BW; P = 0.07) and digested it to a greater extent (0.710 vs. 0.696; P = 0.03), resulting in greater digestible DMI (2.11 vs. 1.97 kg/100 kg of BW; P = 0.03). Sheep consumed (mean = 2.52 kg/100 kg of BW; P = 0.59) and digested (mean = 0.681; P = 0.25) PM- and AM-cut hays similarly. Steers consumed larger quantities of PM-than AM-cut hay (2.90 vs. 2.62 kg/100 kg of BW; P = 0.11), but digestion did not differ with cutting time (mean = 0.660; P = 0.75). Difference values (composition of fed hay minus composition of orts) indicated that sheep and goats selected from the feed offered similarly, whereas steers selected differently. Difference values for CP averaged 94 and 101 g/kg for goats and sheep and 32 g/kg for steers (P < 0.01), and difference values for NDF averaged 185 and 196 g/kg for goats and sheep and 73 g/kg for steers (P 相似文献   

Effect of supplementing Rhodes grass hay (Chloris gayana) with Berchemia discolor or Zizyphus mucronata on the performance of growing goats in Kenya

Twenty growing Small East African goats were used to determine the effects of feeding sun-dried leaves of the browse forages Berchemia discolor and Zizyphus mucronata as supplements to low-quality basal diet, Rhodes grass (Chloris gayana) hay, on voluntary feed intake (VFI), digestibility and growth performance. The grass hay and maize bran were used as a control. The dried leaves were then included at the rates of 15% and 30% of the dry matter intake (DMI). Berchemia discolor had the highest crude protein (CP) content of 195.5 g/kg DM, while Z. mucronata had CP content of 169.5 g/kg DM. The grass hay had the lowest CP content of 50.9 g/kg DM. The browse forages had low fibre content [Neutral detergent fibre (NDF); 257.9-369.5 g/kg DM], while the grass hay had high fibre content (NDF; 713.1 g/kg DM). Goats in the groups supplemented with either of the browse forages had higher total DMI, nitrogen (N) intake and retention and live-weight gains than those in the control diet group. The digestibility of DM and organic matter (OM) was not affected by supplementation, but the CP digestibility increased with supplementation. The use of the browse forages as supplements for goats fed on poor-quality basal diets would enhance the performance of the animals.     

Effects of corn condensed distillers solubles supplementation on ruminal fermentation, digestion, and in situ disappearance in steers consuming low-quality hay

Two metabolism (4 x 4 Latin square design) experiments were conducted to evaluate the effects of corn condensed distillers solubles (CCDS) supplementation on intake, ruminal fermentation, site of digestion, and the in situ disappearance rate of forage in beef steers fed low-quality switchgrass hay (Panicum virgatum L.). Experimental periods for both trials consisted of a 9-d diet adaptation and 5 d of collection. In Exp. 1, 4 ruminally and duodenally cannulated steers (561 +/- 53 kg of initial BW) were fed low-quality switchgrass hay (5.1% CP, 40.3% ADF, 7.5% ash; DM basis) and supplemented with CCDS (15.4% CP, 4.2% fat; DM basis). Treatments included 1) no CCDS; 2) 5% CCDS; 3) 10% CCDS; and 4) 15% CCDS (DM basis), which was offered separately from the hay. In Exp. 2, 4 ruminally and duodenally cannulated steers (266.7 +/- 9.5 kg of initial BW) were assigned to treatments similar to Exp. 1, except forage (Panicum virgatum L.; 3.3% CP, 42.5% ADF, 5.9% ash; DM basis) and CCDS (21.6% CP, 17.4% fat; DM basis) were fed as a mixed ration, using a forage mixer to blend the CCDS with the hay. In Exp. 1, ruminal, postruminal, and total tract OM digestibilities were not affected (P = 0.21 to 0.59) by treatment. Crude protein intake and total tract CP digestibility increased linearly with increasing CCDS (P = 0.001 and 0.009, respectively). Microbial CP synthesis tended (P = 0.11) to increase linearly with increasing CCDS, whereas microbial efficiency was not different (P = 0.38). Supplementation of CCDS to low-quality hay-based diets tended to increase total DM and OM intakes (P = 0.11 and 0.13, respectively) without affecting hay DMI (P = 0.70). In Exp. 2, ruminal OM digestion increased linearly (P = 0.003) with increasing CCDS, whereas postruminal and total tract OM digestibilities were not affected (P > or = 0.37) by treatment. Crude protein intake, total tract CP digestibility, and microbial CP synthesis increased (P < or = 0.06) with increasing level of CCDS supplementation, whereas microbial efficiency did not change (P = 0.43). Ruminal digestion of ADF and NDF increased (P = 0.02 and 0.008, respectively) with CCDS supplementation. Based on this data, CCDS used in Exp. 2 was 86.7% rumen degradable protein. The results indicate that CCDS supplementation improves nutrient availability and use of low-quality forages.     

Feeding value of diets containing almond hulls

Four mature geldings were used in a 4 X 4 Latin Square digestion experiment to determine the digestibility of pelleted diets containing 0. 15, 30 and 45% Nonpareil almond hulls. The four isonitrogenous treatments consisting of almond hulls, oat hay, and alfalfa hay provided approximately 94% dry matter (DM), 11% crude protein (CP), 23-32% acid detergent fiber (ADF) and 4100 kcal/kg gross energy (GE). Each horse consumed a different diet during each of four 14-day trial periods. Horses were fed 10 kg of their assigned diet per day. The horses gained an average of 15 kg over the course of the 8-week study. No feed was refused in any of the trials and there were no signs of adverse reactions to any of the diets. The digestibilities of the four dietary components (DM, CP, ADF and GE) were not affected by horse or trial period. Dry matter and GE digestibilities increased (P<.05) as the almond hull content increased in the four diets (59, 63, 64 and 68% DM digestibility and 57, 61, 61 and 64% GE digestibility, respectively). Acid detergent fiber digestibility was not affected by almond hull content (39, 39, 39 and 42% digestibility, respectively) while CP digestibility decreased as the almond hull content increased in the four diets (69, 62, 66 and 56% digestibility, respectively). Almond hulls appear to be a safe and palatable feed for horses and can be fed up to levels of 45%.     

Effects of canola seed supplementation on intake, digestion, duodenal protein supply, and microbial efficiency in steers fed forage-based diets

Fourteen Holstein steers (446 +/- 4.4 kg of initial BW) with ruminal, duodenal, and ileal cannulas were used in a completely randomized design to evaluate effects of whole or ground canola seed (23.3% CP and 39.6% ether extract; DM basis) on intake, digestion, duodenal protein supply, and microbial efficiency in steers fed low-quality hay. Our hypothesis was that processing would be necessary to optimize canola use in diets based on low-quality forage. The basal diet consisted of ad libitum access to switchgrass hay (5.8% CP; DM basis) offered at 0700 daily. Treatments consisted of hay only (control), hay plus whole canola (8% of dietary DM), or hay plus ground canola (8% of dietary DM). Supplemental canola was provided based on the hay intake of the previous day. Steers were adapted to diets for 14 d followed by a 7-d collection period. Total DMI, OM intake, and OM digestibility were not affected (P > or = 0.31) by treatment. Similarly, no differences (P > or = 0.62) were observed for NDF or ADF total tract digestion. Bacterial OM at the duodenum increased (P = 0.01) with canola-containing diets compared with the control diet and increased (P = 0.08) in steers consuming ground canola compared with whole canola. Apparent and true ruminal CP digestibilities were increased (P = 0.01) with canola supplementation compared with the control diet. Canola supplementation decreased ruminal pH (P = 0.03) compared with the control diet. The molar proportion of acetate in the rumen tended (P = 0.10) to decrease with canola supplementation. The molar proportion of acetate in ruminal fluid decreased (P = 0.01), and the proportion of propionate increased (P = 0.01), with ground canola compared with whole canola. In situ disappearance rate of hay DM, NDF, and ADF were not altered by treatment (P > or = 0.32). In situ disappearance rate of canola DM, NDF, and ADF increased (P = 0.01) for ground canola compared with whole canola. Similarly, ground canola had greater (P = 0.01) soluble CP fraction and CP disappearance rate compared with whole canola. No treatment effects were observed for ruminal fill, fluid dilution rate, or microbial efficiency (P > or = 0.60). The results suggest that canola processing enhanced in situ degradation but had minimal effects on ruminal or total tract digestibility in low-quality, forage-based diets.     

Dry Matter Intake and Apparent Digestibility of Nutrients in the Ration of Mangalarga Marchador Weanling Horses Fed Sorghum Silage Versus Grass Hay

In central Brazil, there are two well-defined climatic periods, the rain and the dry season, the latter being marked by massive forage shortages in pastures. In this context, forage conservation such as making hay and silage for herbivores is imperative during the dry season. Grass hay is most commonly used for horses, but sorghum silage is often used for ruminants. The objective was to compare the nutrient digestibility, fecal production, and dry matter intake (DMI) of sorghum silage (Sorghum bicolor l. Moench CV. BRS 655) to that of vaquero hay (Cynodon CV. 90160 CD × CV. Mirage). Twelve Mangalarga Marchador fillies (8 months of age) were divided into two groups: S (sorghum silage, n = 6) and F (vaquero hay, n = 6). The ration was formulated to supply 3.0% body weight in dry matter (DM) per day, with a forage:concentrate ratio of 50:50 on a DM basis. The concentrate used was a corn-based ration formulated to meet or exceed requirements for growth when fed at 1.5% body weight DM to young horses. The animals were housed in individual stalls (3 × 3m) for a period of 25 days, with 21 days for adaptation, followed by 4 days of total collection of feces. During the collection period, an external marker of digestibility, Purified and Enriched Lignin (LIPE), was added to the concentrate as an external marker to determine the apparent digestibility coefficients of DM, crude protein, gross energy, neutral detergent fiber, acid detergent fiber, hemicelluloses, and cellulose. The forage DMI was calculated by subtracting the quantity supplied at each meal minus the amount of forage that was not eaten by the next meal (orts). The measures of digestibility of the sorghum silage were not different (P > .05) from that of vaquero hay. However, DMI of the sorghum silage was lower (P < .05) than the vaquero hay and may be of concern if fed for prolonged periods of time and not supplemented with carefully balanced concentrates. Purified and Enriched Lignin can be used as a marker for evaluation of digestibility of nutrients in weanling horses.     

Intake and digestion of low-quality meadow hay by steers and performance of cows on native range when fed protein supplements containing various levels of corn

Two trials were conducted to evaluate the effects of corn in protein supplements fed to cattle receiving low-quality forages. In Trial 1, four ruminally cannulated steers (avg BW 500 kg) and four intact steers (avg BW 270 kg) were used in a replicated latin square to determine intake and digestibility fo a low-quality meadow hay (4.3% CP) when fed no supplement (NS), 1.12 g CP/kg BW (PS), 1.12 g CP/kg BW with corn supplying 1.98 g starch/kg BW (PLC) or 1.12 g CP/kg BW with corn supplying 3.96 g starch/kg BW (PHC). Hay DMI decreased (P = .001) and total diet DMI increased (P = .001) quadratically as supplemental corn increased. Diet DM digestibility increased (P = .004) and forage DM and hemicellulose digestibility decreased (P less than or equal to .018) quadratically as level of corn in the diet increased. In Trial 2, 135 cows received either ear corn (1.16 kg TDN and 127 g CP.hd(-1).d(-1), ear corn plus protein (1.16 kg TDN) and 290 g CP g CP.hd(-1).d(-1) or protein (.72 kg TDN and 290 g CP.hd(-1.d(-1) while grazing native Sandhills winter range for 112 d and while receiving hay (10% CP) during the following 60-d calving period. Cows that received ear corn lost (P less than .001) more weight than cows fed ear corn plus protein supplement, which lost more weight than cows fed only protein supplement (-54, -18 and 6 kg, respectively) during the 112-d winter grazing period. Cows that received ear corn and ear corn plus protein gained more (P less than .001) weight during calving and summer grazing (after supplement wa withdrawn) than protein-supplemented cows. Reproductive performance was not affected (P greater than .705) by treatments.     

Intake, digestion, and N metabolism in steers fed endophyte-free, ergot alkaloid-producing endophyte-infected, or nonergot alkaloid-producing endophyte-infected fescue hay

A digestion and N balance trial was conducted to compare effects of traditional endophyte-infected (E+), endophyte-free (E-), and nontoxic endophyte infected (NE; MaxQ; Pennington Seed, Inc., Madison, GA) Jesup tall fescue (Festuca arundinacea Schreb.) hay on digestion and N retention in steers. Hay composition (DM basis) was as follows: E+ (10.8% CP, 59.9% NDF, and 29.4% ADF), E- (11.8% CP, 58.5% NDF, and 28.4% ADF), and NE (11.6% CP, 58.6% NDF, and 28.3% ADF). Eight Polled Hereford steers (initial BW 240 +/- 9 kg) were used in a replicated, 3 x 3 Latin square design, with an extra steer allotted to each square. Steers were fed ad libitum for 14 d, followed by a 9-d adaptation to restricted intake (based on the animal with the lowest ad libitum intake for the square) and a 5-d fecal and urine collection. Water intake (20.2 L/d) and urine output (7.40 L/d) did not differ (P > 0.10) during the collection period. Plasma prolactin concentration was less (P < 0.05) for steers on the E+ hay (8.83 ng/mL) than for those on the E- hay (18.03 ng/mL) and intermediate for steers on the NE hay (12.65 ng/mL). Endophyte-infected hay differed (P < 0.05) from E- and NE in ad libitum DMI (5.02 vs. 5.62 and 5.61 kg/d, respectively) and ad libitum DMI as a percentage of BW (1.86 vs. 2.06 and 2.06%, respectively). Restricted DMI during the fecal and urine collection was lower (P < 0.05) for E+ hay than for E- (5.04 vs. 5.24 kg/d), and NE was intermediate (5.19 kg/d). Dry matter digestibility was lower (P < 0.05) for E+ compared with E- and NE (62.3 vs. 67.0 and 65.9%, respectively). Digestibility of ADF was lower (P < 0.05) for E+ than for E-, and was intermediate for NE (61.5, 66.0, and 63.9%, respectively). There were no differences for NDF, cellulose, or hemicellulose digestibilities among hay types. Crude protein digestibility was higher (P < 0.05) for E- and NE than for E+ (54.3 and 52.5 vs. 48.1%, respectively). Nitrogen retention was lower (P < 0.01) for E+ than for E- or NE (15.6 vs. 22.7 or 23.0 g/d, respectively). Hay type did not influence plasma urea N, urine urea N output, or urine urea N as a percentage of urinary N. Results from this study indicate that E+ tall fescue hay was lower in ad libitum DMI, DM digestibility, and N retention than NE or E- hays with similar chemical composition. Hay from NE and E- fescue had nearly identical composition, and did not differ for any variable measured.