Haylage Diets Research Articles

67 Digestibility and glycemic response of timothy-based haylage and timothy grass hay

Haylage is often fed to horses around the world and may be an appealing forage choice for certain horses due to its low dust content and lower NSC content when compared with hay of comparable species and maturity. The objective of this study was to determine if there were differences in digestibility and glycemic response between hay and haylage of similar quality. Four Thoroughbred geldings (9.3 ± 1.5 yr; 617 ± 40 kg; mean ± SD) were used in a crossover design with 2 dietary treatments over 2 28-d periods. The 2 dietary treatments were second-cutting timothy hay and timothy-ryegrass haylage both fed at 1.5% BW (DM basis). To minimize refusals, one horse was fed at 1% BW (DM basis) for the last 9 d of each period. The hay contained 15% WSC, 0.7% starch, 35% ADF, and 57% NDF, and the haylage contained 9% WSC, 0.8% starch, 39% ADF, and 66% NDF (DM basis). The hay and haylage had similar lignification of the cell wall fraction (lignin/NDF; 9.1% vs 8.4%, respectively). Total fecal collections were conducted during the last 5 d of each period to determine digestibility. Glycemic response to a meal of the assigned forage was conducted on d 22of each period by analyzing plasma for glucose every 30 min for 480 min post-feeding and calculating the area under the curve (AUC). The effect of treatment was analyzed using an ANOVA (SAS Institute Inc., Cary NC) and significance was defined when P < 0.05. The AUC per g of NSC was not different between diets (P > 0.10). Horses had a slower rate of DM intake when fed the haylage meal (10 g DM/min versus 25 g DM/min for hay; P < 0.05) and also had a longer time to peak glucose (P < 0.05). Dry matter digestibility was 58.1% for hay and 50.4% for haylage (P < 0.05). Despite containing a similar degree of cell wall lignification, the hay diet resulted in a greater digestibility of NDF and ADF compared with the haylage diet (P < 0.05). Horses fed haylage had greater fecal moisture than horses fed hay (86% and 76%; P < 0.05) and demonstrated free fecal water. The appearance of free fecal water may have been related to the lower-than-expected fiber digestibility in the haylage diet. More research is needed to determine causative factors in the development of free fecal water in horses.

Effects of replacing corn silage with alfalfa haylage in growing beef cattle diets on performance during the growing and finishing period.

Corn silage is the predominant mechanically harvested forage source for feedlot cattle production in the United States because of high yield. Alternatively, because of multiple cuttings per year and lower annual cost, the use of alfalfa or other forages, may increase opportunities for manure spreading, perennial soil cover, pollinator habitat, and greater carbon sequestration. The objective of this trial was to determine the feeding value of alfalfa haylage when replacing corn silage in growing cattle diets. One-hundred-sixty-five Angus crossbred steers [326 ± 51 kg of body weight (BW)] were blocked by initial BW and randomly assigned to one of 28 pens at the University of Minnesota feedlot. Pens were randomly assigned to dietary growing treatments. The control diet was comprised of (DM basis) 50% corn silage, 19.25% rolled corn grain, 19.25% high moisture corn, 7% dried distillers grains plus solubles, and 4.5% liquid supplement (corn silage control, CS Control). For alfalfa haylage (AH) diets, AH substituted corn silage at 33% (AH 33), 66% (AH 66), or 100% (AH 100). Growth performance measurements [dry matter intake (DMI), average daily gain (ADG) and gain to feed (G:F) ratio] were assessed for 42 to 70 d depending on BW block. Afterwards, steers were fed a common finishing diet until harvested. There was a linear increase in DMI (P < 0.01) with increasing AH inclusion. Replacing CS with AH linearly decreased (P ≤ 0.05) ADG and G:F. No differences (P ≥ 0.10) were observed in finishing performance or carcass traits. Results from this study demonstrated that greater substitution of corn silage with alfalfa haylage in growing diets resulted in greater intake but reduced rate of gain and gain:feed. Despite slower rate of gain, cattle fed alfalfa haylage at increasing proportions during the growing period were able to compensate in BW gains during the finishing period and reached harvest weight and backfat thickness at similar days on feed than those fed corn silage. Based on these results the energy value of corn silage and alfalfa haylage were 3.05 and 2.39 Mcal ME/kg of DM, respectively, when included at 50% of the diet DM.

The effect of diet-induced obesity and pasture on blood pressure and serum cortisol in Standardbred mares.

Obesity is associated with insulin resistance, vascular dysfunction and altered cortisol metabolism both in humans and in horses. Evaluate the effect of weight gain induced by a haylage diet low in nonstructural carbohydrates (NSC) on insulin sensitivity, blood pressure and serum cortisol concentrations. In vivo experiment. Nine adult Standardbred mares fed a fat supplemented haylage diet at 250% of the horses' daily metabolisable energy requirements for 22weeks. Horses were then turned out on pasture for 4weeks. Insulin sensitivity (SICLAMP ) was measured before and after weight gain and after 4weeks of pasture using the euglycemic hyperinsulinaemic clamp (EHC) method. Body condition score (BCS), blood pressure and serum cortisol were monitored throughout the study. All data were analysed using the linear mixed model procedure. Values of P<0.05 were considered as statistically different. All horses became obese during the weight gain period (BCS>7). Mean arterial blood pressure (MAP) increased during the weight gain period and was significantly higher than initial values at the end of the weight gain period (78±3mm Hg vs 92±3mmHg). MAP remained increased on pasture (93±3mmHg). SICLAMP was unaffected by weight gain 0.9±0.1 vs 1.0±0.1 ([mg/kg/min×103 ]/[µIU/mL×mmol/L])) but improved after pasture (1.6±0.1 ([mg/kg/min×103 ]/ [mU/L]). Serum cortisol concentrations increased during the weight gain period (80±9nmol/L vs 112±9nmol/L) and remained increased during pasture. Limited number of horses and no control group. Obesity was associated with a linear increase in blood pressure and an increase in serum cortisol that was not associated with insulin sensitivity.

Evaluation of glucose and insulin response to haylage diets with different content of nonstructural carbohydrates in 2 breeds of horses

Information about the effect of nonstructural carbohydrates (NSCs) in forage on the postprandial glucose and insulin response in horses is scarce. This is of interest as postprandial hyperinsulinemia in horses is a risk factor for laminitis. In addition, insulin sensitivity (IS) differs between breeds. The aim was to evaluate the postprandial glucose and insulin response to haylage diets with different NSC content in horses of 2 different breeds and to evaluate the relationship between the postprandial insulin response and measures of IS derived from a frequently sampled intravenous glucose tolerance test (FSIGTT). Standardbreds (n = 9) and Icelandic horses (n = 9) with a mean body condition score of 5.5 ± 0.6 (scale 1–9) were studied. Horses were clinically healthy at the start of the study and had no history of endocrinopathic laminitis. The experiment was conducted as a replicate 3 × 3 Latin square, in which horses were fed haylage diets with low (4.2%), medium (13.6%), and high (18.2%) NSC content of dry matter. Blood sampling was performed before feeding and every 30 min until 300 min after feeding. An FSIGTT was also performed in all horses. The early (first 60 min) and the total (300 min) postprandial glucose and insulin response (area under the curve [AUC]) was higher after a meal of both medium and high NSC haylage in comparison with low NSC haylage when both breeds were combined (P ≤ 0.02). There was a main effect of breed for the early (P ≤ 0.004) but not for the total (P > 0.12) postprandial glucose and insulin response. The IS index was comparable between breeds (P = 0.75). The natural logarithm of the peak concentration, the AUC for the first 60 min and the total AUC for insulin, after a meal of medium and high NSC haylage, were moderately negatively correlated (P < 0.02; r = −0.55 to −0.72) with the natural logarithm of IS index from the FSIGTT. This relationship was not evident for haylage with low NSC content (P > 0.054). This study demonstrates that the postprandial insulin response is affected by both the NSC content of haylage and the horse's IS. However, the impact of IS was diminished when the NSC content in haylage was low (4.2% of dry matter).

Effects of straw processing and pen overstocking on the growth performance and sorting characteristics of diets offered to replacement Holstein dairy heifers

Our objectives were to evaluate the effects of pen-stocking density and straw processing on the growth performance, feed-bunk sorting behaviors, and hygiene of Holstein dairy heifers. Two corn silage-alfalfa haylage diets diluted with wheat straw were offered; diet composition was identical, except that one diet contained short (well-processed) straw (SS; 46.0% neutral detergent fiber, 12.9% crude protein, 60.7% total digestible nutrients, TDN), and the other long (poorly processed) straw (LS; 46.5% neutral detergent fiber, 12.6% crude protein, 60.0% TDN; % of dry matter basis). A 2 × 3 factorial arrangement of straw-processing (SS or LS) and pen-stocking-density [100, 125, or 150% of capacity] treatments was evaluated with 240 Holstein dairy heifers (410 ± 56.3 kg) that were blocked by weight, and then assigned to 24 pens with 4 pens/interactive treatment. For 91 d, diets were dispersed at 1100 h daily, and bunks were sampled subsequently at 1300, 1600, 1900, 2200, 0100, and 0600 h during 3 evaluation periods throughout the trial. Diets were offered for ad libitum intake, but with minimal orts (<3%); as such, particle-size concentration factors were calculated as bunk concentration/initial concentration. For the LS diet, particle-size concentration factors for large (>19 mm) particles increased linearly from 1.26 to 2.82 across sampling times, differing from the SS diet at 2200, 0100, 0600, and 0900 h (orts). Similar factors calculated for the SS diet also increased linearly across sampling times, but these responses were less severe (1.27 to 1.97). Overall, particle-size concentration factors for physically effective fiber exhibited responses similar to those observed for large particles, except they were limited to narrower ranges for both the SS (1.04 to 1.14) and LS (1.03 to 1.26) diets. Despite these differences, daily dry matter intake was not affected by treatment (mean = 9.65 kg of dry matter/d), nor was daily intake of TDN (mean = 5.92 kg of TDN/d). For SS, heifers housed within overstocked pens exhibited reduced average daily gain (ADG) compared with the 100% stocking rate (0.93 vs. 0.99 kg/d). With LS processing, ADG differed between the 125 and 150% stocking rates (0.96 vs. 0.88 kg/d), as did the within-pen coefficient of variation for ADG (10.7 vs. 18.6%). Hygiene scores (1 = clean, 4 = caked-on manure) for legs (range = 2.1 to 2.3) and flanks (range = 1.6 to 1.9) indicated heifers stayed acceptably clean, but the within-pen coefficient of variation for legs (14.4 vs. 9.0%) and flanks (34.2 vs. 23.8%) was greater for overstocked pens compared with the 100% stocking density, thereby suggesting hygiene scores were more variable without a free stall for each heifer.

Effects of Feeding Calcium Hydroxide Treated Corn Stover During Backgrounding on Beef Carcass and Quality Characteristics

ObjectivesSixty-seven purebred Angus steers (initial BW 197 ± 38 kg.) were used to evaluate the effects of calcium hydroxide treated corn stover in backgrounding diets and a common finishing phase.Materials and MethodsSteers were randomly assigned to 1 of 4 treatments: untreated corn stover (CON), corn stover treated with 50% DM water (H2O); 50% DM water and calcium hydroxide treated corn stover (CaOH2); grazing on a turnip cover crop (CC) for 29 d before adapted to ad libitum alfalfa haylage diet fed in feed bunks for remaining 20 d of backgrounding. Steers were fed individually using a Calan system. All diets were formulated on a dry matter (DM) basis to contain 30% corn stover, 15% alfalfa haylage, 25% dried distillers grains with solubles, 25% dry rolled corn, and 5% supplement containing monensin. Steers were harvested at 240 d on feed. Carcass characteristics were recorded 48 h postmortem. Strip loins and shoulder clods (IMPS #180 and #114) from the right side of the carcass were collected. The shoulder clods were frozen immediately on arrival to the meat lab. Strip loins were fabricated into 2.54 cm steaks at 96 h postmortem. Strip loin steaks were used to evaluate vacuum purge, cook loss, and Warner-Bratzler shear force (WBSF). Shoulder clods were processed to ground beef before processing into bologna. Consumer sensory panels comprised of untrained panelists were utilized for both strip steaks (n = 130) and bologna (n = 126) to evaluate overall liking, flavor liking, texture liking, toughness, juiciness, and off-flavor. Data was analyzed using Proc Mixed of SAS 9.4 (SAS Inst. Inc., Cary, NC).ResultsTreatment had no effect on HCW (P = 0.694), REA (P = 0.259), backfat (P = 0.780), USDA Yield Grade (P = 0.890), USDA Quality Grade (P = 0.877), and marbling score (P = 0.845). Although purge loss (P = 0.884) and cook loss (P = 0.149) were not affected by treatment, WBSF values were lower for CC than CON (1.6 vs. 2.23kg respectively; P = 0.001). Objective L* and b* values for bologna were different among treatments (P < 0.001) with CaOH2 being higher than all other treatments. Objective a* values were lower for H2O than CC and CaOH2 (P < 0.001) and higher for CC and CaOH2 than CON on Day 0 (P = 0.002 and P < 0.001 respectively). For steak sensory, no differences were found in flavor liking (P = 0.102), juiciness (P = 0.375), or off-flavor (0.313). Differences were found in overall liking (P = 0.008) with CC being more liked than CON (P = 0.013) and CaOH2 (P = 0.019). Texture liking (P < 0.001) for CC was higher than CON (P < 0.001), H2O (P = 0.021), and CaOH2 (P < 0.001). Toughness scores were lowest for CC (P < 0.001) compared to CON (P < 0.001), H2O (P = 0.015), and CaOH2 (P < 0.001). For bologna sensory, no differences among treatments were found in overall liking (P = 0.610), flavor liking (P = 0.707), texture liking (P = 0.828), juiciness (P = 0.371), and off-flavor (P = 0.716). A difference in toughness was found (P = 0.011) with H2O being more tough than CaOH2 (P = 0.008).ConclusionThe use of calcium hydroxide treatment in backgrounding diets of beef calves does not affect carcass characteristics or moisture loss, but does affect processed meat shelf life, and sensory characteristics for fresh steaks and bologna.

Growth performance and sorting characteristics of corn silage-alfalfa haylage diets with or without forage dilution offered to replacement Holstein dairy heifers

Gravid heifers consuming high-quality forage diets are susceptible to excessive weight gains and overconditioning. One approach for controlling this problem is to dilute diets with low-energy forages, such as straw, that reduce the caloric density and dry matter intake (DMI) of that diet by heifers. These diluting agents are often sortable by dairy heifers, but previous visual evidence has suggested that eastern gamagrass haylage may be a nonsortable alternative. Our objectives were (1) to compare the growth performance of dairy heifers offered a high-quality forage diet (control) with diets containing 1 of 3 diluting agents [eastern gamagrass haylage (EGH), chopped wheat straw (WS), or chopped corn fodder (CF)]; and (2) evaluate sorting behaviors of heifers offered these forage diets. Holstein heifers (n=128) were stratified (32 heifers/block) on the basis of initial body weight (heavy, 560±27.7kg; medium-heavy, 481±17.7kg; medium-light, 441±22.0kg; and light, 399±14.4kg), and then assigned to 1 of 16 identical research pens (4 pens/block; 8 heifers/pen), where each of the 4 research diets were assigned to 1 pen within each block. Diets were offered in a 118-d feeding trial with heifers crowded to 133% of capacity at the feed bunk. Inclusion of low-energy forages was effective in reducing both diet energy density and DMI. Concentrations of physically effective fiber (pef) particles did not change during the 24-h period following feeding for either the control or EGH diets; however, this response for pef particles masked the competing (and cancelling) responses for individual large and medium particles, which heifers sorted with discrimination and preference, respectively. Sorting against pef particles was detected for WS, and much more severely for the CF diet. Sorting of forage particles by heifers could not be related to heifer performance. Compared with control (1.16kg/d), average daily gains (ADG) were reduced by dilution in all cases, but were virtually identical between EGH (0.98kg/d) and CF (0.97kg/d), which exhibited no sorting and extensive sorting of pef, respectively. Furthermore, ADG for WS was approximately 0.2kg/d less than EGH or CF, despite exhibiting sorting characteristics intermediate between EGH and CF. Diets diluted with low-energy forages were formulated to be isonitrogenous and isocaloric; within that context, WS was most effective in reducing DMI and maintaining ADG within typical recommendations for Holstein heifers.

Maral Deer Meat Productivity and Meat Quality When Using the Different Types of Diets

Thirty-three stag maral deer (Cervus elaphus sibiricus) 42 month old were allocated to one of three treatment groups: hay-concentrate typical diet, silage and haylage diets with a mineral block (zeolite clay, boiled antler broth and fodder salt). When mineral block was included in diets higher levels carcass weight, flesh weight, dry matter, pH were measured. Besides this meat and broth sensory qualities were improved.

On the relationships between glucocorticoids and feed efficiency in beef cattle

Improvement in the utilization of feed in livestock is an important target of breeding and nutritional programs. Recent evidence indicates a potential association between feed efficiency and fecal cortisol metabolites, which could eventually be used as an indirect assessment of this trait. This evidence is more comprehensively evaluated in here with samples for plasma cortisol (PC; ng/ml) and fecal cortisol metabolites (FCM; ng/ml) collected more often during the entire finishing phase in beef steers. Individual daily feed intake of 112 steers fed a high-moisture corn-based and haylage diet was measured over 168d. Body weight, blood and fecal samples were collected every 14d and ultrasound measures of backfat thickness and longissimus muscle area were taken every 28d. Four productive performance traits were calculated: daily dry matter intake (DMI), average daily gain (ADG), feed to gain ratio (F:G) and residual feed intake (RFI). At the end of the feedlot phase, steers were ranked according to RFI and samples were analyzed for PC and FCM from the 32 steers with greatest and 32 steers with lowest feed efficiency. In addition, a sub-group of 12 steers from each of these two groups with divergent feed efficiency were subjected to hourly blood sampling for 24h. Less efficient steers had greater DMI, F:G and consumed 1.5kg/d more DMI (P<0.05) than steers with improved feed efficiency. No differences (P>0.10) in PC over the 12 biweekly sampling periods between steers with divergent feed efficiency were observed. However, a trend toward significance between 19:00 and 02:00h over the hourly sampling evaluation was noticed, with the sub-group of more feed efficient steers presenting higher levels of PC in this period of the day (P=0.08). On the other hand, FCM levels displayed a distinct pattern between RFI groups over the biweekly sampling period, with more efficient cattle presenting greater levels of these metabolites (P<0.05). This study reinforces the positive association between improved feed efficiency and FCM levels over the finishing phase; and the lack of association between feed efficiency and PC when single samples are collected every two weeks through a single jugular venipuncture performed after handling the cattle for sampling. Further studies to develop sampling protocols for assessing FCM as an indicator trait for feed efficiency are warranted, as well as, studies to understand the role of endogenous glucocorticoids in the performance of the bovine.

Effect of nutritional regimen including limit feeding and breed on growth performance, carcass characteristics and meat quality in beef cattle

McGregor, E M., Campbell, C. P., Miller, S. P., Purslow, P. P. and Mandell, I. B. 2012. Effect of nutritional regimen including limit feeding and breed on growth performance, carcass characteristics and meat quality in beef cattle. Can. J. Anim. Sci. 92: 327–341. The effects of nutritional management regimen and breed on growth performance, carcass attributes, and meat quality were evaluated in 68 British (BRIT) and Continental (CONT) crossbred steers, managed on one of three nutritional regimens: (1) ad libitum access to a 77% corn diet (ALGRAIN), (2) limit feeding initially of the 77% corn diet, followed by ad libitum access to the 77% corn diet (LFGRAIN), and (3) limit feeding initially of a 90% haylage diet, followed by ad libitum access to the 77% corn diet (LFHAYL). Nutritional regimen by breed interactions (P&lt;0.02) were present for average daily gain, dry matter intake (DMI), gain to feed, and shear force. LFHAYL regimen decreased gains to a greater extent for BRIT steers than CONT steers managed on ALGRAIN or LFGRAIN. Feed intakes were similar across nutritional regimens for CONT steers, while DMI was depressed in BRIT on LFHAYL as compared with steers started on ALGRAIN or LFGRAIN. Gain to feed was greater in BRIT cattle on LFGRAIN vs. ALGRAIN, while gain to feed was similar in CONT started on grain (ALGRAIN, LFGRAIN). Shear force was lower for beef from LFHAYL BRIT vs. beef from BRIT on ALGRAIN or LFGRAIN, while the converse was true for CONT. Limit feeding of a high-energy diet may be appropriate for cattle of British background to reduce feed input costs, while ensuring tenderness.

Using eastern gamagrass to construct diets that limit intake and caloric density for dairy replacement heifers

Previous research has shown that eastern gamagrass (EGG; Tripsacum dactyloides L.) will survive winter climatic conditions common throughout central Wisconsin, and will produce yields of dry matter (DM) ranging approximately from 7,000 to 10,000kg/ha annually when managed with a 1-cut harvest system. The objective of this research was to determine whether the fibrous nature of this perennial warm-season grass could be effective in reducing the caloric density and DMI of corn silage/alfalfa haylage diets for replacement dairy heifers. A total of 120Holstein dairy heifers were blocked by body weight (heavy, 424±15.9kg; medium, 369±11.8kg; light, 324±22.4kg), and then assigned to 15 individual pens containing 8heifers each. Eastern gamagrass forage was harvested, ensiled, and subsequently incorporated into blended corn silage/alfalfa haylage diets at rates of 0, 9.1, 18.3, or 27.4% of the total dietary DM (EGG0, EGG9, EGG18, and EGG27, respectively). These diets were offered during a 105-d evaluation period for ad libitum intake; however, the EGG0 diet also was offered on a limit-fed basis (LF), which was set at 85% of the voluntary intake of EGG0. Serial additions of EGG increased concentrations of neutral detergent fiber in blended diets from 39.6 (EGG0) to 48.7% (EGG27), and simultaneously reduced corresponding estimates of total digestible nutrients (TDN) from 68.2 to 61.3%, and net energy for gain from 1.07 to 0.83Mcal/kg. Dry matter intakes for all diets offered ad libitum were greater than observed for LF (9.06 vs. 8.07kg/d); however, DM intakes for diets containing EGG were reduced relative to EGG0 (9.40 vs. 8.94kg/d). Similarly, intakes of TDN were greater for diets offered for ad libitum intake than for LF (5.84 vs. 5.50kg/d); however, inclusion of EGG reduced TDN intakes relative to EGG0 (6.41 vs. 5.65kg/d). This reduction was explained by both linear and quadratic effects of the inclusion rate of EGG in the diet. Over the 105-d trial, total weight gains ranged from 89kg (0.85kg/d) for heifers offered EGG27 up to 114kg (1.09kg/d) for those offered EGG0. Performance was similar between heifers offered EGG27 and LF diets (0.85 vs. 0.88kg/d). Eastern gamagrass haylage proved to be a completely nonsortable additive within corn silage/alfalfa haylage diets. It also was effective in limiting the caloric density and DM intake of these diets, as well as undesirable weight gains by dairy heifers.

Equine digestion of diets based on haylage harvested at different plant maturities

Health problems in horses related to overfeeding of nutrients is increasing, but, at the same time, horses require long eating time in order to avoid development of some stereotypic behaviours. Increasing the amount of forage in the ration without increasing uptake of nutrients is therefore of interest, and was studied by examining effects of plant maturity at harvest of haylage on its digestion in horses. Haylage was harvested in June, July and August from primary growth of the same grass-dominated sward. Twelve adult horses of European warmblood type were divided into three groups and fed the haylages in a change-over experiment consisting of three consecutive periods of three weeks, so that all horses had been fed each of the haylages at the end of the experiment (9 weeks in total). The haylage diets were as close to isoenergetic (metabolisable energy) as possible for each individual horse, and average daily feeding levels were 1.4, 1.5 and 1.8kg dry matter haylage/100kg body weight for June, July and August haylage, respectively. Faecal samples were collected daily during the third week in each period and analysed for content of acid insoluble ash (AIA), biochemical composition and particle size distribution. Haylages were sampled and analysed for AIA content, chemical composition and nutritive value. Results showed that the dry matter digestibility was highest for June haylage (0.75) and lowest for August haylage (0.44), with July haylage (0.59) intermediate (P<0.0001). Feeding June haylage also resulted in a larger proportion of particles <0.1mm in faeces compared to feeding July and August haylage (P<0.0001). Chemical composition and pH in faeces differed among haylage diets: when June haylage was fed, pH was lower and content of total volatile fatty acids (VFA) was higher compared to when July and August haylage was fed (P<0.0001). An effect of feeding level on digestibility could not be ruled out, as later cut haylages were fed in higher amounts than earlier cut haylage. A late harvest date of haylage made it possible to increase the amount of forage in equine diets without increasing digestibility or uptake of nutrients in horses given moderate exercise, probably due to a combination of low digestibility of mature plants and the higher feeding level needed to meet the nutrient requirements of the horse with an all or almost all forage diet.

Effects on the equine colon ecosystem of grass silage and haylage diets after an abrupt change from hay1

The objective of this study was to investigate the effect of an abrupt change from grass hay (81% DM) to grass silage (36% DM) or grass haylage (55% DM), fed at similar DM intakes, and to compare the effects of silage and haylage on the composition and activities of the colon microflora. The forages were from the same swath harvested on the same day. Four adult colon-fistulated geldings were randomly assigned to diets in a crossover design. The study started with a preperiod when all 4 horses received the hay diet, followed by an abrupt feed change to the haylage diet for 2 horses and the silage diet for 2 horses. All 4 horses then had a new second preperiod of hay, followed by an abrupt feed change to the opposite haylage and silage diet. The periods were 21 d long, and the forage-only diets were supplemented with minerals and salt. The abrupt feed changes were made at 0800 h. Colon samples were taken before the abrupt feed change, 4 and 28 h after the feed change, and 8, 15, and 21 d after the feed change, all at 1200 h. Colon bacterial counts, VFA, pH, and DM concentrations were unchanged throughout the first 28 h after the abrupt feed change from hay to haylage and silage. Also, fecal pH and DM concentrations were unchanged during the first 28 h. During the weekly observations, colon lactobacilli counts increased (P = 0.023) in horses receiving the silage diet and were greater than on the haylage diet at 21 d. Streptococci counts decreased (P = 0.046) in horses receiving the haylage diet and were less than on the silage diet at 15 and 21 d. Total VFA concentrations and colon and fecal pH did not differ between diets and were unchanged throughout the weekly observations. The DM concentration of colon digesta and feces decreased (P = 0.030 and 0.049, respectively) on both diets during the weekly observations. The results suggest that in horses fed at the maintenance level of energy intake, an abrupt feed change from grass hay to grass silage or grass haylage from the same crop does not induce any major alterations in the colon ecosystem during the first 28 h. During the subsequent 3-wk period, colon and fecal DM decreased and there were alterations in the lactobacilli and streptococci bacterial counts. The changes in lactobacilli and streptococci counts need further investigation.

The influence of low versus high fibre haylage diets in combination with training or pasture rest on equine gastric ulceration syndrome (EGUS)

The aim of this field study was to examine the influence of a low fibre (LF) and a high fibre (HF) diet on the presence of gastric ulceration in thirty 3-year old Dutch Warmblood horses during training period and during pasture rest. In the first part of the study all horses were stabled individually and fed either an iso-energetic HF (75% haylage) or LF (25% haylage) diet for sixteen weeks. Horses were exercised daily throughout this period, after which the first gastroscopy was performed. The second gastroscopy for all horses was performed following a fourteen week Pasture period during which grass was supplemented with haylage. Contrary to expectations the scores for number and severity of gastric lesions during the Training period were significantly higher in the HF group compared to the LF group. Additionally, horses of the HF group showed high haylage retention in the stomach after 12 hours fasting, whilst the LF group exhibited marked bedding eating and coprophagia. The results of gastroscopy following the Pasture period with extra haylage feeding for all horses, were similar to the HF horses following the Training period. These unexpected results may be related to the retention of the pre-fermented feed (haylage) in the stomach leading to continuing fermentation with increased volatile fatty acid (VFA) production in the stomach. The consumption of bedding and coprophagy shown by the LF group may have limited the previously reported high risk of gastric ulceration on a lowfibre diet.

Effect of source and amount of energy and rate of growth in the growing phase on performance and carcass characteristics of early- and normal-weaned steers.

One hundred eighty-four Angus x Simmental steers (initial BW 161.7 +/- 3.4 kg) were used to determine whether different sources and amounts of energy in the growing phase could extend the growth curve and maintain high amounts of intramuscular fat deposition in early-weaned steers. Steers were allotted by source, age, and BW to one of four growing-phase (119 to 259 d of age) regimens. For three regimens, steers were weaned at 119 d of age and either 1) fed (DM basis) a 50% grain diet ad libitum (ALC); 2) limit-fed a 70% grain diet to achieve a gain of 0.8 kg/d from 119 to 192 d of age, and 1.2 kg/d from 193 to 259 d of age (LFC); or 3) fed a 60% haylage diet ad libitum from 119 to 192 d of age, and a 25% haylage diet ad libitum from 193 to 259 d of age (ALF). For the fourth regimen, steers were normal-weaned at 204 d of age and fed a silage diet from 205 to 259 d of age (NW). From 260 d of age to slaughter, all steers consumed a 70% grain (DM basis) diet. Limit-fed and ALF steers spent the most, and NW the least amount of time (P < 0.01) in the feedlot to achieve a target fat depth of 1.27 cm. Ad libitum-fed steers were the youngest (331 d), and NW the oldest (383 d) at slaughter (P < 0.01). Overall ADG was greatest for ALC and least for NW steers (P < 0.01). Overall, ALF steers consumed the most DM (P < 0.01). While in the feedlot, LFC and ALC steers were more efficient in converting feed to BW gain (P < 0.01) than ALF and NW steers. Normal-weaned had the least and ALC the greatest (P < 0.01) fat depth at 260 d of age. Consequently, NW steers produced the heaviest, and ALC the lightest (P < 0.01) carcasses at slaughter. Normal-weaned steers had the largest, and ALC and LFC steers had the smallest longissimus muscle area (P < 0.06). Growing phase dietary treatments did not affect (P > 0.20) yield grade. Marbling score did not differ (P > 0.35), but laboratory analysis revealed that ALC steers had the lowest percentage of fat (P < 0.02) in the longissimus muscle. Shear force was greatest (P < 0.08) for steaks from ALC and LFC steers, and least for steaks from ALF and NW steers. Feeding steers the ALC diet from 119 to 260 d of age hastened physiological maturity, decreased marbling scores, and decreased muscle tenderness compared with forage feeding (ALF, NW). Limit-feeding a high-grain diet also hastened physiological maturity and decreased muscle tenderness but did not decrease marbling scores. Source and amount of energy affected partitioning of fat deposition.

The effects of corn milling coproducts on growth performance and diet digestibility by beef cattle.

Simmental x Angus weanling heifers (n = 96; 239 +/- 2.3 kg) were used in four replications to evaluate three dietary treatments in Trial 1. Treatments were cracked corn-hay diets supplemented with one of three corn milling industry coproducts: dry corn gluten feed (DCGF), dried distillers grains (DDG), and a new modified corn fiber (MCF). In Trial 2, ruminally cannulated mature crossbred beef steers (n = 4; 606 +/-60 kg) were used in a 4 x 4 Latin square with 11-d periods to determine digestibility and ruminal metabolism of limit-fed cracked corn-alfalfa haylage diets supplemented with cornstarch (CON), DCGF, DDG, or MCF. During Periods 3 and 4, an in situ study was conducted to compare the rate and extent of CP degradation of DCGF, DDG, and MCF. In Trial 1, there were no differences (P > .10) in initial weights or DM intake. Average daily gain and feed efficiency (G/F) were improved (P < .01) for heifers fed DCGF or DDG vs heifers fed MCF. In Trial 2, no differences (P > . 10) in digestibilities of any nutrients or in ruminal VFA concentrations were observed for steers fed coproducts. The CON supplementation decreased (P < .05) total dietary fiber (TDF) digestibility, improved (P < .10) digestibilities of DM and OM, increased (P < .05) total VFA concentrations and concentrations of propionate and valerate, and decreased (P < .05) concentrations of butyrate, isobutyrate, and isovalerate when compared with the coproducts. Dry corn gluten feed increased (P < .05) and DDG tended (P < .10) to increase percentages of the immediately soluble fraction of CP, and both had increased (P < .05) rates (Kd) and greater (P < .05) extent of ruminal CP degradation than MCF. These data suggest that DCGF and DDG may be utilized in limit-fed high-energy diets without sacrificing performance. Feeding of MCF resulted in poorer performance of heifers, suggesting a limited feeding value that results from high ADIN content and slow in situ protein digestion.

Dietary Interaction of Cane Molasses with Source of Roughage: Intake and Lactation Effects

Effects of cane molasses at 0, 4, and 8% of DM in complete mixed diets were evaluated when molasses was fed to lactating dairy cows with cottonseed hulls, alfalfa haylage, or both combined. Thirty-six mature Holstein cows from mid to late lactation were used in a partially balanced incomplete block design with three 28-d periods. Variables measured were DM intake, milk yield, and composition. With cottonseed hull diets (30% of DM), molasses improved milk yield, milk fat percentage, solids-corrected milk, and feed efficiency. Dry matter intake was not affected by molasses. With alfalfa haylage diets (35% of DM), 8% molasses depressed actual milk yield and solids-corrected milk, DM intake, milk fat percentage, milk protein percentage, and feed efficiency. Milk fat percentage was increased with 4% molasses. With 65% alfalfa haylage diets, most variables measured were unaffected by molasses; however, with 8% molasses, DM intake increased and milk protein percentage decreased. In diets with both roughages combined, molasses did not affect any variable measured; however, these diets gave highest solids-corrected milk yields. Results show clearly that molasses effects depend on percentage molasses and type and amount of roughage in the diet.

Effect of soft white wheat addition to alfalfa-grass forage on heifer gain, diet digestibility and in vitro digestion kinetics

The effects of soft white wheat addition to forage diets were studied in three trials. Level of wheat (0, 25 or 50%), in an alfalfa-grass haylage diet fed to heifers in a replicated 3 × 3 Latin square design, linearly ( P < 0.05) increased average daily gain from 0.61 to 0.75 kg day −1 and linearly ( P < 0.05) decreased dry matter intake (DMI) from 6.1 to 6.0 kg day −1 and feed gain ratio ( P < 0.10) from 10.4 to 8.2. Level of wheat (0, 25, 50 or 75%), in an alfalfa-grass hay diet fed to wethers in a 4 × 4 Latin square design digestion trial, quadratically ( P < 0.05) increased starch digestibility from 86.6 to 97.9%, and linearly ( P < 0.05) increased dry matter digestibility from 65.4 to 74.5% and energy digestibility from 63.0 to 72.3%. However, level of wheat linearly ( P < 0.05) decreased cellulose digestibility from 62.8 to 25.4% and acid detergent fiber digestibility from 55.1 to 19.0%. Level of wheat (0, 25, 50, 75 or 100%) addition to alfalfa-grass hay quadratically increased ( P < 0.05) in vitro rate (from 0.034 to 0.050 h −1) and extent of neutral detergent fiber digestion (from 59.8 to 75.0%). These data are interpreted to indicate that large negative associative effects on cellulose and acid detergent fiber digestibility occurred at 75% wheat addition to an alfalfa-grass hay. However, small positive associative effects on digestibility of dry matter, starch and energy, and in vitro rate of neutral detergent fiber occurred when small amounts of wheat were added to an alfalfa-grass forage.

Quantitation of Microorganisms Associated with the Particulate Phase of Ruminal Ingesta

Microbial organic matter associated with rumen particulate and fluid phases was quantified using 15N as the microbial marker in two rumen fistulated cows fed a 65% alfalfa haylage diet. During two collection periods, feed was removed 1 h after initiation of feeding, and cows were dosed with (15NH4)2SO4. Whole rumen contents were sampled before feeding and at various times up to 12 h after feeding. Fluid microorganisms were those that passed through eight layers of cheesecloth. Particle-associated microorganisms were obtained by chilling squeezed particles prior to seven successive extractions with saline solution. The amount of microorganisms removed from particles ranged from 32.1 to 59.9% as measured by 15N. Organic matter (mg/mL strained rumen fluid equivalent) of fluid and particle-associated microorganisms was respectively: 10.7 and 47.5; 12.5 and 35.5; 12.2 and 30.1; 10.7 and 26.1; 10.9 and 26.7; and 8.9 and 20.6, at 2, 3, 4, 7, 9 and 11 h after initiation of feeding. These ratios indicated that 70–80% of microbial organic matter in whole rumen contents was associated with the particulate phase and that particle-associated microbial organic matter was greatest soon after feeding. Analysis of 15N in extracted rumen particles indicated that 50–65% of particle nitrogen and 17–27% of particle dry matter was of microbial origin. These results provide evidence that particle-associated microorganisms make up a major proportion of the total microorganisms in ruminal ingesta and that a large proportion of ingesta particle N can be of microbial origin.

Effect of calcium phosphates and zinc in salt-mineral mixtures on ad libitum salt-mix intake and on zinc and selenium status of sheep.

In two separate experiments, 72 crossbred ewes were fed hay, haylage (50% dry matter) and corn diets with ad libitum salt-mineral mixtures (SMM; Exp. 1) or salt (Exp. 2). Calcium phosphates (Ca X P) and(or) zinc (Zn) were added in a 2 X 2 factorial arrangement to salt + trace minerals for ewes 7 mo prepartum through lactation in Exp. 1 and to salt only for ewes 3 mo prepartum through lactation in Exp. 2. The diets fed were estimated to contain 23 and 28 mg Zn/kg dry diet (ppm), respectively, and .08 and .05 ppm Se. Large variations (up to fivefold) were found in SMM intake per month between replicates and from month-to-month within treatment; thus, monthly variations of up to sevenfold occurred in Zn and Se intakes of supplemented groups. There were no significant treatment effects on SMM intake. Small but significant Zn treatment effects were detected for plasma and wool Zn of ewes and lambs, but all values were in the normal range. There was no significant treatment effect on plasma alkaline phosphatase activity. In Exp. 2, erythrocyte glutathione peroxidase (GSH-Px) activity was significantly lower in all treatment groups compared with a Se-supplemented control group but only rare occurrences of subclinical muscular dystrophy were found. There was no significant treatment effect on GSH-Px activity, whole blood Se in ewes and lambs or plasma creatine phosphokinase activity in lambs. These results indicate large animal and seasonal variability in SMM intake and no significant treatment effects of Ca X P on SMM intake or on Zn and Se status. Zinc addition to SMM had no effect on Se status.