Effect of calcium salts of fatty acids on rumen function and the digestibility of rations by sheep

Experiments were conducted to determine the effects of supplementing chopped ryegrass hay with 0, 1.5, 3, 6 or 12% calcium salts of fatty acids (CaSFA; Megalac) on digestion in the rumen of cannulated cows and on nutrient digestibility by sheep. In-situ ruminal disappearances of dry matter (DM) and cell wall fractions (acid detergent fibre, ADF, and neutral detergent fibre, NDF) were measured by the nylon bag technique. The DM, ADF and NDF disappearances were reduced for diets containing CaSFA at the 1.5, 3 or 6% levels after 48 h of rumen exposure. For diets containing 12% CaSFA, irrespective of the time of rumen incubation, DM disappearance was decreased, while ADF and NDF breakdown was improved. CaSFA supplementation did not influence invitro fermentation characteristics (pH, volatile fatty acid patterns). A digestibility experiment with six mature sheep showed no difference in nitrogen digestibility between unsupplemented and CaSFA-supplemented diets. However, digestibilities of DM, ADF and NDF were higher relative to the basal for the 12% CaSFA: 63.1 versus 60.6%, 63.8 versus 58.7% and 67.4 versus 62.7%, respectively. Ether extract digestion was enhanced by increasing the level of CaSFA, the corresponding values being 49.1, 66.5, 78.6, 81.9 and 77.9% at 0, 1.5, 3, 6 and 12% CaSFA, respectively. Apparent digestibility of energy was higher for the 12% CaSFA than the control diet 68.8 versus 62.1%). Nitrogen and energy retention was improved due to the decreases in urine and faecal excretion, respectively.     

Effects of bale moisture and bale diameter on spontaneous heating, dry matter recovery, in vitro true digestibility, and in situ disappearance kinetics of alfalfa-orchardgrass hays

Alfalfa (Medicago sativa L.)-orchardgrass (Dactylis glomerata L.) hay was made in 96 large-round bales over 3 harvests during 2006 and 2007 to assess the effects of spontaneous heating on dry matter (DM) recovery, in vitro true digestibility (IVTD), and in situ disappearance kinetics of DM. Throughout these harvests, bales were made at preset diameters of 0.9, 1.2, or 1.5 m and at moisture concentrations ranging from 9.3 to 46.6%. Internal bale temperatures were monitored daily during an outdoor storage period, reaching maxima of 77.2°C (MAX) and 1,997 heating degree days >30°C (HDD) for one specific combination of bale moisture, bale diameter, and harvest. Following storage, regressions of DM recovery on HDD and MAX indicated that DM recovery declined linearly in close association with measures of spontaneous heating. For HDD, slopes and intercepts differed across bale diameters, probably because the greater surface area per kilogram of DM for 0.9-m bales facilitated more rapid dissipation of heat than occurred from 1.2- or 1.5-m-diameter bales. Regardless of bale diameter, coefficients of determination were high (r² ≥ 0.872) when HDD was used as the independent variable. Regressions of DM recovery on MAX also exhibited high r² statistics (≥ 0.833) and a common slope across bale diameters (−0.32 percentage units of DM/°C). Changes in concentrations of IVTD during storage (poststorage - prestorage; ΔIVTD) also were regressed on HDD and MAX. For HDD, the data were best fit with a nonlinear model in which ΔIVTD became rapidly negative at <1,000 HDD, but was asymptotic thereafter. When MAX was used as the independent variable, a simple linear model (y = −0.23x + 9.5) provided the best fit. In both cases, coefficients of determination were comparable to those for DM recovery (R² or r² ≥0.820). Changes (poststorage - prestorage) in ruminal DM degradation rate (ΔK_d) and effective ruminal degradability of DM (ΔDEG) were assessed similarly. Although the most appropriate statistical model varied, ΔK_d and ΔDEG both became increasingly negative at low to moderate levels of heating, but generally stabilized thereafter. Both HDD and MAX were excellent predictor variables for both ΔK_d and ΔDEG; r² or R² statistics ranged from 0.788 to 0.921. Measures of spontaneous heating are consistently effective indicators of DM recovery following storage, as well as good indicators of concurrent changes in IVTD or in situ disappearance of DM for heated alfalfa-orchardgrass hays.     

Effect of silk flower hay (Calotropis procera Sw) feeding on the physical and chemical quality of Longissimus dorsi muscle of Santa Inez lambs

The effect of different levels of silk flower hay (Calotropis procera Sw) in the diet of confined lambs by the substitution of the commonly used foraging broom corn hay (Sorghum bicolor L) was investigated to evaluate its possible effects on the growth and quality of the lamb meat. Twenty-four male Santa Inez lambs were divided in equal numbers into four treatment groups and fed diets containing 0%, 16.7%, 33.3% and 50% of silk flower hay (SFH). Growth rate, feed intake and meat quality were investigated. Mean daily gains of lambs were 170 g for control, 180.5 g for 16.7% SFH, 96.8 g for 33.3% SFH and 22.9 g for 50% SFH. The use of silk flower hay in the diet of Santa Inez lambs affected health of the animals and meat pH when the substitution of the forage was high, up to 50%; however, the general meat quality was not affected. Meat from animals fed with levels up to 50% SFH had physical (Aw, a^*, b^* and L^*) and chemical (moisture, ash, lipid, phosphorus, iron, phospholipid and fatty-acid profile) parameters comparable to the control group (0% SFH). Among the various levels of substitution (16.7%, 33.3% and 50%) of silk flower hay in the diet tried in this work, the use of 16.7% was found to be an attractive and technically viable option for the Northeast region of Brazil.     

Effects of spontaneous heating on fiber composition, fiber digestibility, and in situ disappearance kinetics of neutral detergent fiber for alfalfa-orchardgrass hays

During 2006 and 2007, forages from 3 individual hay harvests were utilized to assess the effects of spontaneous heating on concentrations of fiber components, 48-h neutral detergent fiber (NDF) digestibility (NDFD), and in situ disappearance kinetics of NDF for large-round bales of mixed alfalfa (Medicago sativa L.) and orchardgrass (Dactylis glomerata L.). Over the 3 harvests, 96 large-round bales were made at preset bale diameters of 0.9, 1.2, or 1.5 m, and at moisture concentrations ranging from 9.3 to 46.6%. Internal bale temperatures were monitored daily during an outdoor storage period, reaching maxima (MAX) of 77.2°C and 1,997 heating degree days >30°C (HDD) for one specific combination of bale moisture, bale diameter, and harvest. Concentrations of all fiber components (NDF, acid detergent fiber, hemicellulose, cellulose, and lignin) increased in response to spontaneous heating during storage. Changes in concentrations of NDF during storage (poststorage - prestorage; ΔNDF) were regressed on HDD using a nonlinear regression model (R² = 0.848) that became asymptotic after ΔNDF increased by 8.6 percentage units. Although the specific regression model varied, changes (poststorage - prestorage) in concentrations of acid detergent fiber, cellulose, and lignin also increased in nonlinear relationships with HDD that exhibited relatively high coefficients of determination (R² = 0.710 to 0.885). Fiber digestibility, as determined by NDFD, was largely unaffected by heating characteristics except within bales incurring the most extreme levels of HDD or MAX. In situ assessment of ruminal NDF disappearance kinetics indicated that disappearance rate (K_d) declined by about 40% within the range of heating incurred over these hay harvests. The change in K_d during storage (ΔK_d) was related closely to both HDD and MAX by nonlinear models exhibiting high R² statistics (0.907 and 0.883, respectively). However, there was no regression relationship between changes (poststorage - prestorage) in effective ruminal disappearance of NDF and spontaneous heating, regardless of which heating measure was used as the independent variable. The close regression relationship between ΔK_d and measures of spontaneous heating indicates clearly that ruminal NDF disappearance was altered negatively by some direct or indirect aspect of spontaneous heating. However, it was equally apparent that these effects were offset by an expanding pool of dry matter recovered as potentially degradable NDF.     

Forage type influences milk yield and ruminal responses to wheat adaptation in late-lactation dairy cows

The effects of different wheat adaptation strategies on ruminal fluid pH, dry matter intake (DMI) and energy-corrected milk (ECM) were measured in 28 late-lactation dairy cows. Cows were fed either perennial ryegrass (PRG) hay or alfalfa hay and had no previous wheat adaptation. Wheat was gradually substituted for forage in 3 even increments, over 6 or 11 d, until wheat made up 40% of DMI (～8 kg of dry matter/cow per day). We found no differences in DMI between adaptation strategies (6 or 11 d) within forage type; however, cows fed alfalfa hay consumed more overall and produced more ECM. The rate of ruminal pH decline after feeding, as well as the decrease in mean, minimum, and maximum ruminal pH with every additional kilogram of wheat was greater for cows fed alfalfa hay. Cows fed alfalfa hay and on the 6-d adaptation strategy had the lowest mean and minimum ruminal fluid pH on 3 consecutive days and were the only treatment group to record pH values below 6.0. Despite ruminal pH declining to levels typically considered low, no other measured parameters indicated compromised fermentation or acidosis. Rather, cows fed alfalfa hay and adapted to wheat over 6 d had greater ECM yields than cows on the 11-d strategy. This was due to the 6-d adaptation strategy increasing the metabolizable energy intake in a shorter period than the 11-d strategy, as substituting wheat for alfalfa hay caused a substantial increase in the metabolizable energy concentration of the diet. We found no difference in ECM between adaptation strategies when PRG hay was fed, as there was no difference in metabolizable energy intake. The higher metabolizable energy concentration and lower intake of the PRG hay meant the increase in metabolizable energy intake with the substitution of wheat was less pronounced for cows consuming PRG hay compared with alfalfa hay. Neither forage type nor adaptation strategy affected time spent ruminating. The higher intakes likely contributed to the lower ruminal pH values from the alfalfa hay treatments. However, both forages allowed the rumen contents to resist the large declines in ruminal pH typically seen during rapid grain adaptation. Depending on the choice of base forage, rapid grain introduction may not result in poor adaptation. In situations where high-energy grains are substituted for a low-energy, high-fiber basal forage, rapid introduction could prove beneficial over gradual strategies.     

Production performance,nutrient digestibility,and milk fatty acid profile of lactating dairy cows fed corn silage- or sorghum silage-based diets with and without xylanase supplementation

The objective of this study was to evaluate the effects of supplementing xylanase on production performance, nutrient digestibility, and milk fatty acid profile in high-producing dairy cows consuming corn silage- or sorghum silage-based diets. Conventional corn (80,000 seeds/ha) and brown midrib forage sorghum (250,000 seeds/ha) were planted, harvested [34 and 32% of dry matter (DM), respectively], and ensiled for more than 10 mo. Four primiparous and 20 multiparous Holstein cows were randomly assigned to 1 of 4 diets in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments and 19-d periods. Treatment diets consisted of (1) corn silage-based diet without xylanase, (2) corn silage-based diet with xylanase, (3) sorghum silage-based diet without xylanase, and (4) sorghum silage-based diet with xylanase. The xylanase product was supplemented at a rate of 1.5 g of product/kg of total DM. Corn silage had higher concentrations of starch (31.2 vs. 29.2%), slightly higher concentrations of crude protein (7.1 vs. 6.8%) and fat (3.7 vs. 3.2%), and lower concentrations of neutral detergent fiber (36.4 vs. 49.0%) and lignin (2.1 vs. 5.7%) than sorghum silage. Xylanase supplementation did not affect DM intake, milk yield, milk fat percentage and yield, milk protein percentage and yield, lactose percentage and yield, and 3.5% fat-corrected milk yield. Cows consuming corn silage-based diets consumed 13% more DM (28.8 vs. 25.5 kg/d) and produced 5% more milk (51.6 vs. 48.9 kg/d) than cows consuming sorghum silage-based diets. Milk from cows consuming sorghum silage-based diets had 16% greater fat concentrations (3.84 and 3.30%) than milk from cows consuming corn silage-based diets. This resulted in 8% greater fat yields (1.81 vs. 1.68 kg/d). Silage type did not affect milk protein and lactose concentrations. Xylanase supplementation did not affect nutrient digestibility. Cows consuming corn silage-based diets showed greater DM (77.3 vs. 73.5%), crude protein (78.0 vs. 72.4), and starch (99.2 vs. 96.5%) digestibilities than cows consuming sorghum silage-based diets. In conclusion, xylanase supplementation did not improve production performance when high-producing dairy cows were fed corn silage- or sorghum silage-based diets. In addition, production performance can be sustained by feeding sorghum silage in replacement of corn silage.     

Design and experimental evaluation of a solar dryer for commercial high-quality hay production

Design, experimental functional performance and economic evaluation of an energy efficient commercial-type solar energy dryer for production of high-quality hay, especially for the export market, are presented. The newly developed solar hay dryer consists of a solar collector with aluminum absorber plate and spaced fins, a drying shed with perforated metal grate floor above the ground level, swing-away plywood frames and polyethylene curtains for effectively sealing the hay stack during drying operations, an insulated duct, and a crawl space below the floor where a 3-hp in-line centrifugal fan is housed for air circulation by suction. In late August and in early September, 1996, 160 small rectangular bales of alfalfa hay with about 25% bromegrass were successfully dried from 33% initial moisture content to 13% moisture and from 25% to 11% moisture in 4 and 3 days, respectively, under average weather conditions in Saskatoon, Canada. The air temperature rise above ambient was 13–15 °C during peak bright sunshine hours in August and 10–13 °C in September. Ambient relative humidities ranged from 30–90%. Unlike field-cured hay, the hay produced by the dryer was of high-quality and remained green in colour and attractive after drying. Compared to field drying or conventional natural gas drying system, the payback period on investment in full-scale solar hay drying system may be just one to two years.     

Occurrence and significance of mycotoxins in forage crops and silage: a review

Study of mycotoxins in animal feeding stuffs has concentrated on the occurrence of aflatoxins and, to a lesser extent, other mycotoxins in cereals, raw materials and concentrate feeds. However, ruminant diets contain a high proportion of forage crops such as grass or maize silage, hay and straw. Under adverse growing, production or storage conditions, fungal spoilage is likely to occur with some degree of mycotoxin contamination. The mould flora of forage crops is likely to differ significantly from that of cereals and mycotoxin contamination, should it occur, could differ qualitatively and quantitatively. Information relating to forage crops as a potential source of mycotoxins is reviewed. Some field incidents and animal disease which may be mycotoxin related are discussed and analytical methods are reviewed. Information on dose and effect of candidate mycotoxins is given where available. The review suggests areas which the authors consider merit further study. Crown Copyright 1998.     

Timothy hays differing in dietary cation-anion difference affect the capability of dairy cows to maintain their calcium homeostasis

Forages low in dietary cation-anion difference (DCAD) can be used to decrease the DCAD in prepartum diet but the extent to which DCAD needs to be reduced is of recent interest. The objective of this study was to evaluate the effectiveness of timothy hays differing in DCAD at maintaining Ca homeostasis. Six nonlactating and nonpregnant multiparous Holstein cows were fed diets containing timothy (Phleum pratense L.) hay with DCAD values of 4.1 ± 3.6 (LOW), 14.1 ± 3.0 (MED), or 25.1 ± 2.5 (HIGH) mEq per 100 g of DM in a duplicated 3 × 3 Latin square design with 14-d experimental periods. The LOW and MED hays were produced by fertilizing established timothy fields at a rate of 224 kg CaCl₂ per ha, and HIGH hay was obtained from the same field where LOW hay was produced, but from a section not fertilized with CaCl₂. Experimental diets, containing LOW, MED, or HIGH timothy hay at 71% of dietary DM, had DCAD values of 0.7, 7.3, and 14.4 mEq per 100 g of DM, respectively. Animals were fed at 6% of metabolic body weight, which provided 108% of their daily energy requirement. For each period, after a 12 d diet adaptation, cows were subjected to an EDTA challenge (3 cows each on d 13 and 14). Infusion of EDTA solution into the jugular vein decreases the concentration of blood ionized Ca, and the EDTA challenge protocol determined the resistance time and recovery time: the time required for the blood ionized Ca concentration to decrease to 60%, and the time required to recover to 90% of the prechallenge concentrations, respectively. Urine pH was lower when cows were fed LOW compared with HIGH diet (6.88 vs. 7.83), but urine pH when cows were fed MED diet (7.15) did not differ from that when cows received the LOW or HIGH diet. However, immediately before the EDTA challenge, blood pH was lower when cows were fed LOW or MED compared with HIGH diet (7.44 vs. 7.47). Although the resistance time was not affected by treatments, the recovery time was shorter when cows were fed the LOW compared with MED or HIGH diet (185 vs. 248 and 263 min, respectively). Blood pH decreased when cows were fed the LOW or MED diet, but the capability to maintain Ca homeostasis was enhanced only when cows received the LOW diet, in which the DCAD value was decreased to 1 mEq per 100 g of DM.     

Effects of feeding flaxseed or sunflower-seed in high-forage diets on beef production,quality and fatty acid composition

Yearling steers were fed 70:30 forage:concentrate diets for 205 d, with either grass hay (GH) or red clover silage (RC) as the forage source, and concentrates containing either sunflower-seed (SS) or flaxseed (FS), each providing 5.4% oil to diets. Feeding diets containing SS versus FS significantly improved growth and carcass attributes (P < 0.05), significantly reduced meat off-flavor intensity (P < 0.05), and significantly increased intramuscular proportions of vaccenic (t11-18:1), rumenic (c9,t11-CLA) and n − 6 fatty acids (FA, P < 0.05). Feeding diets containing FS versus SS produced significantly darker and redder meat with greater proportions of atypical dienes (P < 0.05). A significant forage × oilseed type interaction (P < 0.05) was found for n − 3 FA, α-linolenic acid, and conjugated linolenic acid, with their greatest intramuscular proportions found when feeding the RC-FS diet. Feeding GH versus RC also significantly improved growth and carcass attributes, sensory tenderness (P < 0.05) and significantly influenced intramuscular FA composition (P < 0.05), but overall, forage effects on FA profiles were limited compared to effects of oilseed.