Effects of the ruminal comminution rate and microbial contamination of particles on accuracy of in situ estimates of ruminal degradability and intestinal digestibility of feedstuffs

Effects of considering the comminution rate (k_c) and the correction of microbial contamination (using ¹⁵N techniques) of particles in the rumen on estimates of ruminally undegraded fractions and their intestinal digestibility were examined generating composite samples (from rumen‐incubated residues) representative of the undegraded feed rumen outflow. The study used sunflower meal (SFM) and Italian ryegrass hay (RGH) and three rumen and duodenum cannulated wethers fed with a 40:60 RGH to concentrate diet (75 g DM/kgBW^0.75). Transit studies up to the duodenum with Yb‐SFM and Eu‐RGH marked samples showed higher k_c values (/h) in SFM than in RGH (0.577 vs. 0.0892, p = 0.034), whereas similar values occurred for the rumen passage rate (k_p). Estimates of ruminally undegraded and intestinal digestibility of all tested fractions decreased when k_c was considered and also applying microbial correction. Thus, microbial uncorrected k_p‐based proportions of intestinal digested undegraded crude protein overestimated those corrected and k_c?k_p‐based by 39% in SFM (0.146 vs. 0.105) and 761% in RGH (0.373 vs. 0.0433). Results show that both k_c and microbial contamination correction should be considered to obtain accurate in situ estimates in grasses, whereas in protein concentrates not considering k_c is an important source of error.     

In situ ruminal amino acid degradability of green and ensiled Italian rye-grass according to particle transit model and microbial contamination correction

The ruminal degradation of amino acids (AA) of a green Italian rye-grass (GRG) and its silage (ERG) was determined on three wethers cannulated in rumen and duodenum using in situ and particle passage techniques. Wethers were fed a diet of ERG, corn silage and concentrate (1:1:1, DM basis) at 40 g DM/kg BW^0.75. Two rumen incubations (at 0, 2, 4, 8, 16, 24, 48 and 72 h) with freeze-dried samples (3 g) in nylon bags were performed for each feed. The microbial contamination of incubated residues was corrected using ¹⁵N enriched solid associated bacteria isolates as reference. Two different estimates of undegraded AA were established: UP_p, considering the particle rumen outflow rate (k_p) of the ERG, and UP_cp, considering additionally the rate of comminution and mixing (k_c) of these particles. Microbial contamination resulted in large errors in the degradation kinetic parameters of all AA. As a result, non corrected UP_p and UP_cp included a large fraction of microbial origin. For essential AA plus cysteine these microbial proportions ranged 0.365–0.555 (UP_p) and 0.461–0.710 (UP_cp) in GRG. In ERG these values ranged: 0.403–0.666 (UP_p) and 0.481–0.804 (UP_cp). Cysteine always supplied minimum values whereas lysine showed maximum values in GRG or very close to these in ERG. Ensiling was associated with large changes in the AA profile. These variations conditioned, in turn, large differences in the changes made by the rumen microorganisms on the AA profile of both forages. However, ensiling only led to little changes in the profile of the rumen undegraded protein, especially when k_c was considered. Results show the need to correct for this contamination to obtain accurate AA valuations and also that the AA profile of the undegraded protein of a green forage may serve as a guide for this profile in its silages.     

The effects of protein sources supplemented with urea-treated potato pulp (PP) silage and feeding levels of the PP silage-based concentrate on feed intake, digestibility and ruminal fermentation in beef steers

Six Japanese Black (Wagyu) steers (average initial weight 467 ± 45 kg) fitted with a ruminal cannula were used in a split‐plot design experiment comprising a 3 × 3 Latin square design (whole‐plot) and a randomized block design (subplot). The whole‐plot treatments were three different feeding levels of urea‐treated potato pulp (PP) silage‐based concentrate: 1.00%, 1.75% and 2.50% of body weight (BW) (on a dry matter (DM) basis). The subplot treatments consisted of the concentrate formulated to contain either soybean meal (SBM) as a rapidly rumen‐degraded protein source or corn gluten meal (CGM) as a slowly degraded protein source. Dry matter intake tended to be lower (P = 0.071) for CGM (8.9 kg/day) than for SBM (9.4 kg/day). Protein sources had no significant effect on digestibility and in situ degradation. Ruminal ammonia nitrogen (NH₃‐N) was lower (P = 0.033) for CGM (7.5 mg/dL) than for SBM (9.5 mg/dL). Protein sources did not affect ruminal pH and the total volatile fatty acids (VFA) concentrations. The molar proportions of ruminal acetate and valerate were higher (P = 0.032) for CGM than for SBM. The maximum daily intake of the PP silage‐based concentrate expressed as a percentage of BW was approximately 1.4% of BW. Dry matter intake was higher (P = 0.046) for steers fed at 1.0% of BW of the PP silage‐based concentrate than for steers fed at 1.75% or 2.5% of BW of the concentrate. The feeding levels of the PP silage‐based concentrate had no effect on DM and nutrients digestibility, except for crude protein (CP) digestibility. CP digestibility tended to be lower (P = 0.071) for steers fed at 1.75% of BW of the PP silage‐based concentrate than for steers fed at 1.0% or 2.5% of BW of the concentrate. The feeding levels of the PP silage‐based concentrate also did not affect the in situ degradation parameter of hay and PP silage. The feeding levels of the PP silage‐based concentrate did not affect ruminal pH, NH₃‐N and total VFA concentrations. The molar proportion of acetate was highest for steers fed at 1.0% of BW of the concentrate. In conclusion, in the urea‐treated PP silage‐based concentrate, CGM seems to be more effective than SBM for stabilizing the ruminal NH₃‐N concentration and to be advantageous for fiber digestion in the rumen. The feeding levels of the PP silage‐based concentrate did not change the amount of VFA production in the rumen and the DM digestibility.     

Effects of soybean meal supplementation on ruminal kinetics of feed particle size reduction and passage in dairy cows fed rice straw

Six ruminal-cannulated nonlactating Holstein Friesian cows (mean body weight:660 ± 42.9 kg) were used to investigate the effect of soybean meal (SBM) supplementation on voluntary rice straw (RS) intake, feed particle size reduction, and passage kinetics in the rumen. They were allocated to two dietary treatments: RS alone or RS supplemented with SBM. Voluntary dry matter intake of RS and total tract fiber digestibility was increased by SBM supplementation (p < 0.05). Supplementation with SBM decreased rumination time per dietary dry matter (DM) and neutral detergent fiber (NDFom) intake (p < 0.01). Particle size distribution in the rumen and total ruminal NDFom digesta weights were not affected by SBM supplementation. However, the disappearance rates of total digesta and large and small particles from the rumen were increased by SBM supplementation (p < 0.01). Moreover, SBM supplementation increased the rate of size reduction in ruminal particles (p < 0.05). In situ disappearance of DM and NDFom of RS in the rumen was greater in SBM-supplemented cows than in nonsupplemented cows (p < 0.05). This study clearly showed that increased ruminal RS particle size reduction, passage, and fermentation due to SBM supplementation accelerated the RS particle clearance from the rumen and resulted in increased voluntary RS intake of dairy cows.     

Influence of condensed tannin on intake, digestibility, and efficiency of protein utilization in beef steers fed high concentrate diet

This trial was conducted to evaluate if the effect of condensed tannin (CT) is associated with a true protein source on intake, ruminal and total digestibility, ruminal digestion rate, protein efficiency, and microbial efficiency in beef steers fed high concentrate diet (87% of DM). Four Bos indicus steers (407 ± 12 kg of BW) fitted with rumen cannula were assigned to a 4 × 4 Latin square design, arranged in a 2 × 2 factorial arrangement. Treatments consisted of either inclusion (0.4% of DM) or exclusion of condensed tannin (CT) from quebracho extract (76% of CT) with or without the use of soybean meal (SBM) as source of true protein. The level of inclusion was calculated to provide a daily intake of 1 g/10 kg of BW of CT. Intake of DM and nutrients was not affected (P > 0.10) by CT inclusion. However, there was an effect (P < 0.10) of CT inclusion on ether extract digestibility. An interaction (P < 0.10) was observed between CT and SBM on ruminal digestibility and digestion rate of crude protein (CP): when mixed with soybean meal, CT decreased the ruminal digestibility and, consequently, reduced the digestion rate of CP. Intake of CP increased (P < 0.10) with the inclusion of SBM. No differences in DM passage rate were observed (P > 0.10) among treatments. Effects of the interaction (P < 0.10) between CT and SBM were observed on flux of rumen undegradable protein (RUP), metabolizable protein (MP), and on the ratio MP:CP. In the presence of soybean meal, the addition of CT increased (P < 0.10) the flux of RUP and MP, and improved the ratio MP:CP. The yield of microbial protein on the abomasum and the microbial efficiency did not differ among treatments (P > 0.10). There was no difference (P > 0.10) on the pH, VFA, and ruminal ammonia (N-NH₃) with the addition of condensed tannin. The N-NH₃ increased and the ruminal pH decreased with the inclusion of soybean meal (P < 0.10). The utilization of condensed tannin as an additive in beef cattle diets with high level of concentrate and soybean meal as a source of true protein implies positive effects on crude protein utilization, decreasing digestion rate and ruminal digestibility of crude protein and consequently increasing the levels of metabolizable protein, with no changes in the ruminal fermentation parameters.     

Feeding value of whole raw soya beans as a protein supplement for beef cattle consuming low‐quality forages

Experiments (Exp) I and II were conducted to compare raw whole soya beans (WSB), roasted (rWSB) or other protein sources as supplements of low‐quality forages fed ad libitum to beef cattle, upon DM intake (DMI), ruminal and blood parameters, and animal performance. Exp I: treatments for wheat straw fed to four ruminally cannulated steers were (i) Control‐WS: no supplement; (ii) WSB‐WS: whole soya beans; (iii) rWSB‐WS: roasted WSB; and (iv) SBM‐WS: soybean meal–wheat midds mixture; all fed at 1.4 kg DM/day. Exp II: 12 steers grazed deferred grain sorghum (DS) receiving these treatments: (i) Control‐DS: no supplement; (ii) WSB‐DS: 1.26 kg DM/day whole soya beans; and (iii) SFM‐DS: 1.35 kg DM/day of sunflower meal. In Exp I, WS DMI resulted 47, 52 and 41% greater for WSB‐WS, rWSB‐WS and SBM‐WS, respectively, than Control‐WS (p < .05). In Exp II, the DMI of DS was unaffected by supplementation; a substitution of DS by supplement was found for WSB‐DS (p < .05); however, total diet and digestible DMI increased with supplementation (p < .05). Rumen pH in Exp I remained unaffected by supplementation, but N‐NH₃ as well as blood urea‐N in Exp II increased (p < .05). In Exp II, average daily weight gains improved similarly with both supplements compared with Control‐DS. Additionally, feed‐to‐gain ratio decreased (p < .05), being lower for WSB‐DS (8.3) vs. SFM‐DS (9.9). Roasting effects of WSB as a supplement for low‐quality forages were not detected, and all protein sources increased total diet DMI and forage utilization. Only moderate cattle weight gains could be expected for unsupplemented DS.     

谷氨酸渣对秦川肉牛常见饲料瘤胃降解特性的影响

[目的]研究谷氨酸渣对秦川肉牛瘤胃发酵指标、饲料瘤胃有效降解率(ED)的影响。[方法]以5头秦川肉牛为试验动物,试验共120 d,期间测定瘤胃发酵指标和6种粗饲料DM、CP、NDF、ADF的ED。[结果]谷氨酸渣可提高瘤胃pH,降低NH3-N浓度(P<0.05),提高MCP含量、丙酸相对含量(P<0.05);降低乙酸与丙酸比(P<0.05);提高多种饲料的EDDM、EDCP、EDNDF、EDADF(P<0.05)。[结论]综上,谷氨酸渣可降低瘤胃NH3-N,提高MCP含量,降低乙酸与丙酸比;增强碱性磷酸酶的活性;提高多种饲料DM、CP、NDF、ADF的ED。     

Effects of supplementing low‐quality roughages with tree foliages on digestibility,nitrogen utilization and rumen characteristics in sheep: a meta‐analysis

Thirty‐six published studies containing 219 treatment means and 1069 sheep were included in the dataset for meta‐analysis to elucidate responses of foliage supplementation on digestibility, nitrogen balance and rumen parameters. Major predictive variables were percentages of foliages in diets (FL), crude protein (CP) in foliages (FCP), NDF in foliages (FNDF), NDF in basal forages (BNDF), CP in basal forages (BCP), CP in total diets (DCP) and foliage CP intake (FCPI). Organic matter digestibility increased linearly (p = 0.10) with increasing FL, but responded quadratically to DCP (p = 0.021) and BCP (p < 0.001), with maximal OM digestibility occurred at 14.6% of CP in diets (R² = 0.12). The digestibility of CP was affected by FL (p = 0.01), FCPI (p < 0.026), FCP (p < 0.001), FNDF (p < 0.001) and DCP (p < 0.032) positively and quadratically, and maximal response was at 14.1% DCP (p < 0.001), 51% FL (p < 0.001), 29% FCP (p < 0.001) and FCPI of 122 g/day (p < 0.001). The digestibility of NDF increased quadratically (p = 0.09) with increasing FL, peaking at 16% foliage levels, decreased quadratically (p = 0.001) with increasing FNDF and decreased linearly (p = 0.048) with increasing FCPI. Digestible OM and CP intakes were the highest at 37.2% and 42.1% FL, respectively. Fecal N excretion increased linearly with increasing FL (p < 0.001) and DCP (p < 0.001, R² = 0.66). However, FCPI (p = 0.082), FCP (p = 0.003) and BCP (p < 0.001) affected fecal N excretion positively and quadratically. Urinary N excretion increased linearly (p < 0.001) with increasing FL (R² = 0.45), FCPI (R² = 0.79), FCP (R² = 0.51), BCP (R² = 0.72) and DCP (R² = 0.77). Rumen NH₃ concentration was affected positively and quadratically (p = 0.023) by FL with a peak rumen NH₃ level of 160 mg/l at 17.3% FL. However, rumen NH₃ concentration (mg/l) increased linearly with increasing FCP (p = 0.001), FCPI (p = 0.01) and DCP (p < 0.001). In conclusion, catalytic foliage supplementation at low levels, preferably, at 16% may enhance nutrient utilization, while foliage levels up to 42% may result greater performance of sheep fed on low‐quality roughages.     

Effects of heat treatment on protein feeds evaluated in vitro by the method of estimating utilisable crude protein at the duodenum

The effect of heat treatment on the protein value of field beans, lupins and peas was studied using an in vitro method. Protein feeds were subjected to heat treatment for 30, 60 and 90 min in forced air oven at 120, 140 and 160 °C and in autoclave at 105, 120 and 135 °C. The heat‐treated protein feeds were incubated in buffered rumen fluid together with grass silage and barley in complete isonitrogenous diets. The gas production (GP) was recorded continuously, and ammonia‐N (NH₃‐N) concentrations were determined during the in vitro incubation at 8, 24 and 48 h and used to determine the utilisable crude protein (uCP) at the duodenum at 16 h of incubation (uCP₁₆). Heat treatments decreased the concentration of soluble crude protein and increased neutral detergent insoluble CP (NDICP) in all protein feeds compared to untreated. Inclusion of protein feeds to basal diet showed no increase in the uCP₁₆ in untreated field bean diet and only a small numerical increase in the uCP₁₆ concentrations from 160 g/kg dry matter (DM) to 166 and 172 g/kg DM in untreated lupine and pea diets, respectively, indicating high degradability of untreated feeds. Increasing the time and temperature of the heat treatment linearly increased the uCP₁₆ concentrations in field bean and pea diets, but not in lupin diets. Autoclave treatment was more effective in decreasing uCP₁₆ than oven treatment despite the lower temperatures used. However, the combination of highest temperatures and treatment time in autoclave increased acid detergent insoluble CP (ADICP) concentrations in protein feeds, indicating protein damage and decreased intestinal digestibility. Determining in vitro uCP and ADICP shows to be a promising method for evaluating protein value in heat‐treated animal feeds.     

Protection of protein from ruminal degradation by alkali‐induced oxidation of chlorogenic acid in sunflower meal

Lactating ruminants require an adequate supply of absorbable amino acids for the synthesis of milk protein from two sources, that is crude protein (CP) synthesized microbially in the rumen and ruminally undegraded CP (RUP) from feed which can both be digested in the small intestine. Several chemical and physical methods have been identified as being effective in increasing the proportion of RUP of total CP of a feedstuff, yet there is a continuing need for developing and establishing methods which protect feed protein from ruminal degradation with acceptable expenditure of labour and other costs. The objective of this study was to identify and quantify effects of and interactions between chlorogenic acid and protein in solvent‐extracted sunflower meal (SFM) as induced by alkali treatment. Response surface methodology was employed to investigate the influence of pH, reaction time and drying temperature on the resulting SFM and, subsequently, its protein value for ruminants estimated from laboratory values. For this purpose, alkali‐treated SFM was subjected to a fractionation of feed CP according to the Cornell net carbohydrate and protein system as a basis for estimating RUP at different assumed ruminal passage rates (K_p). To estimate the intestinal digestibility of the treated SFM and its RUP, a three‐step enzymatic in vitro procedure was applied. Alkaline treatment of SFM increased RUP values with factors ranging from approximately 3 (K_p=.08/hr) to 12 (K_p=.02/hr). Furthermore, the intestinal digestibility of the alkali‐treated SFM was enhanced by approximately 10% compared to untreated SFM. Increasing pH and reaction time led to both increasing RUP values and intestinal digestibility. In conclusion, a targeted alkaline treatment of naturally occurring compounds in feedstuffs might be a promising approach to provide high‐RUP feeds for ruminants which, at the same time, have improved intestinal digestibility values.     

Influences of grassland degradation on forage availability by sheep in the Inner Mongolian steppes of China

In China and throughout the world, evaluation of the nutrient values of forages has always lagged behind research regarding the nutrient requirements of animals. In this study, the effective degradability and availability of forages were evaluated on undegraded and degraded grassland using a technique where nylon bags were incubated in sheep rumen. We found that the concentrations of organic matter (OM), neutral detergent fiber (NDF), non‐fiber carbohydrates (NFC) and carbohydrates (CHO) of forage were higher (P < 0.05) and the crude protein (CP) concentration was lower (P < 0.05) in the degraded grassland than in the undegraded grassland. The effective degradability (ED) of NFC (ED_NFC) was higher (P < 0.05) and ED_CHO and ED_NDF were lower in the undegraded grassland than in the degraded grassland. The ED_OM and ED_CP were not affected by the type of grassland, which may explain why ED is an inadequate parameter for the evaluation of forage availability. According to an analysis of the ratio of effectively degraded N to OM and NFC, plants of the undegraded grassland can provide more digestive nutrients to meet the requirements of grazing animals compared to plants of the degraded grassland. Results suggested that it is inadequate to consider only chemical composition and effective degradability when evaluating forage availability with grassland degradation. The ratio of effectively degraded N to OM and NFC was an appropriate indicator.     

葡萄糖处理豆粕对蛋白质保护效果的研究

以3头装有永久性瘤胃瘘管的中国荷斯坦奶牛为试验动物,采用尼龙袋法研究分别添加0、1%、3%、5%、7%、9%葡萄糖保护豆粕,对奶牛瘤胃内不同时间点DM、CP消失率及其动态降解率的作用效果。结果表明:在不同时间点下,提高葡萄糖添加量可使DM、CP消失率逐渐降低,所有试验组与未处理组差异均极显著(P<0.01),DM、CP有效降解率降低最高分别达28.78%和24.82%,不同添加量下,添加量为7%、9%的2组组间差异不显著(P>0.05)。本试验结果证明,葡萄糖加热处理是一种有效保护豆粕蛋白质的方法,且葡萄糖的适宜添加水平为7%。     

尼龙袋法评价香蕉叶单宁对瘤胃降解特性的影响

旨在探究香蕉叶单宁对奶牛瘤胃降解特性的影响和评价香蕉叶的饲喂价值。样品分别为苜蓿干草组(100%的苜蓿干草)、苜蓿干草和香蕉叶混合组(50%苜蓿干草+50%香蕉叶)、香蕉叶组(100%香蕉叶)、苜蓿干草组(100%的苜蓿干草)+6%聚乙二醇(6% PEG)、苜蓿干草和香蕉叶混合组(50%苜蓿干草+50%香蕉叶)+6%聚乙二醇(6% PEG)、香蕉叶组(100%香蕉叶)+6%聚乙二醇(6% PEG)。测定样品中的营养成分含量,使用3头安装了瘤胃瘘管的荷斯坦奶牛进行半体内试验,用尼龙袋法测定上述样品在瘤胃内0、2、4、8、12、24、48、72 h的干物质(DM)、粗蛋白质(CP)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)的降解率,得到各营养物质的动态降解参数。结果表明,相较于苜蓿干草,香蕉叶干物质和粗蛋白的快速降解部分、慢速降解部分、慢速降解部分的降解速率、有效降解率是显著低于苜蓿干草的(P<0.001),香蕉叶和苜蓿的NDF的有效降解率没有显著差异。添加了PEG后,香蕉叶和香蕉叶苜蓿混合组的快速降解部分和有效降解率显著高于未添加PEG的两组(P<0.001)。结果表明香蕉叶中的单宁会抑制香蕉叶的瘤胃降解率,因此在使用香蕉叶调制反刍动物的饲料时需要控制单宁的含量。     

Intake,digestibility and rumen dynamics of neutral detergent fibre in cattle fed low-quality tropical forage and supplemented with nitrogen and/or starch

The objective of this work was to evaluate the effects of nitrogenous compounds and/or starch supplementation on the intake, digestibility and rumen dynamics of neutral detergent fibre (NDF) in cattle fed low-quality tropical forage. Four crossbred heifers (Holstein × Zebu) with a body weight 231.9 ± 15.5 kg and fitted with ruminal cannulae were used. The forage fed to the animals consisted of low-quality signal grass (Brachiaria decumbens Stapf.) hay, with an average crude protein (CP) level of 51.6 g/kg, on a dry matter (DM) basis. Four treatments were evaluated: control, without supplementation; supplementation with nitrogenous compounds (CP of the roughage was raised to 100 g/kg), on a DM basis; supplementation with starch at a ratio of 200 g/kg DM of roughage; and supplementation with nitrogenous compounds and starch as described above. A mixture of urea, ammonium sulphate and albumin was used as a source of nitrogenous compounds at a ratio of 4.5:0.5:1.0. The experiment was carried out according to a 4 × 4 Latin square design in a 2 × 2 factorial arrangement. There was a positive effect of the nitrogenous compound supplementation on the DM and NDF intake (P < 0.01). In contrast, starch supplementation decreased forage intake (P < 0.10). Nitrogen supplementation increased the digestibility coefficient of DM and NDF (P < 0.05). Supplementation with nitrogen and starch together increased the microbial assimilation of nitrogenous compounds in the rumen (P < 0.05). We observed that nitrogen supplementation increased the estimated weighted degradation rate of NDF by 14.8%, whilst starch supplementation decreased this rate by 32.5%.     

Nutritive value of forage species grown in the warm temperate climate of Australia for dairy cows: Herbs and grain crops

The objective of this study was to quantify the nutritive characteristics of 6 grain crops and 4 herb forages over 4 seasons, when all species were grown at the same site, under the same climatic and edaphic conditions, and with soil moisture and nutrient availability being non-limiting to growth. The forages grown were maize (Zea mays), sorghum (Sorghum bicolor), millet (Pennisetum americana), wheat (Triticum aestivum), triticale (Triticum × secale), oats (Avena sativa), fodder radish (Raphanu sativa), rape (Brassica rapa), chicory (Cachorium intybus) and plantain (Plantago lanceolata). The in sacco degradation characteristics of organic matter (OM) and crude protein of herbages were measured in the rumen of cannulated sheep in order to calculate the availability of effective rumen degradable protein (ERDP), rumen by pass protein, metabolisable protein (MP) and the synchrony index (I_s), which describes the efficiency of utilization of degradable nitrogen (N) and OM for microbial protein synthesis (MPS) in the rumen.In this study, all grain crops except maize had a ERDP/fermentable metabolizable energy (FME) ratio varying from 14 for millet to 23 for wheat, well above the ratio of 11 required for optimum MPS in the rumen of dairy cows. In contrast, maize had the lowest ERDP/FME ratio of 3, indicating that ERDP would be limiting MPS in the rumen. The availability of MP varied from 58 g/kg DM in maize to 153 g/kg DM in wheat and all forage species except maize were be able to meet the MP requirement of high-producing dairy cows (30 L/milk/day) provided they were able to consume 11 to13 kg DM/cow/day of the forage.The availability of MP from herbs varied from 95 g/kg DM in fodder radish to 163 g/kg DM in plantain, which would be sufficient for high-producing cows, however, most dairy cows could not consume sufficient forage to achieve these high levels of production due to very high nitrate content in rape (mean of 11.1 g/kg DM) and fodder radish (mean of 8 g/kg DM).     

In situ starch and crude protein degradation in the rumen and in vitro gas production kinetics of wheat genotypes

The objective of this study was to determine the variation of in situ ruminal degradation characteristics of dry matter (DM), crude protein (CP) and starch (ST), and to determine the effective degradation (ED) of wheat genotypes. Further, multivariate associations of these in situ values with their corresponding in vitro gas production (GP) kinetics and laboratory measurements were evaluated using correlation and multiple linear regression analyses. Grains of 20 genotypes of wheat were characterized by proximate constituents, amino acid (AA) composition and physical characteristics. Ruminal degradation kinetics were determined by in situ degradation of DM, CP and ST, and subsequent evaluation of in vitro GP relative to time courses. In situ and GP measurements were fitted to an exponential equation, and ED was calculated using passage rates in the rumen of 5%/h (ED5) and 8%/h (ED8). To predict ED8 of CP (EDCP8) and ST (EDST8), correlations were evaluated and stepwise multiple linear regression analyses were applied. Estimated degradation parameters varied considerably between wheat genotypes irrespective of the nutrient tested. Variance in a, b and c was not reflected in the variation of the ED, due to high degradation rates (c). The assumed passage rate also impacted estimation of the ED minimally. Estimated GP parameters varied only slightly among wheat genotypes. Nevertheless, regression models explained up to 80 and 99% of the variance in EDCP8 and EDST8, respectively, and associations between EDST8 and EDCP8 and chemical and physical characteristics of grains were detected. As ST is the primary nutrient in wheat grains and can comprise substantial portions of dairy rations, the total amount of ST as well as its ED in the rumen should be taken into account when wheat is incorporated into dairy rations. Conversely, variance in wheat grain CP degradation was very low and can largely be neglected in practical ration formulation for ruminants.     

Influence of Substituting Dietary Soybean for Air‐Classified Sunflower (Helianthus annuus L.) Meal on Egg Production and Steroid Hormones in Early‐Phase Laying Hens

Soybean meal (SBM) is the most widely and expensive protein source used in the formulation of poultry diets; however, when the price of SBM increases, poultry nutritionists seek alternative sources that are more economical in formulating least‐cost rations. This research aimed to evaluate the effects of dietary air‐classified sunflower meal (SFM) on some productive parameters and plasma steroid hormones in laying hens. In this trial, 20‐week‐old laying hens (ISA Brown strain) in the early phase of production were randomly assigned to two groups and fed wheat middlings‐based diets containing soybean (135 g/kg; 48% CP) or air‐classified SFM (160 g/kg; 41% CP) as the main protein source. Laying performance, egg size and feed conversion ratio were evaluated for 10 week. Plasma steroid hormones (progesterone and oestradiol) in the hens were quantified weekly. Substituting SBM with air‐classified SFM did not change (p > 0.05) the hens' growth performance, whereas feed consumption and efficiency were positively influenced (p < 0.05) by SFM treatment. Egg production rate was improved in hens fed the SFM diet (p < 0.05), as well as the percentage of medium‐size eggs that was higher for SFM treatment (p < 0.05). Steroid hormones levels were affected by dietary treatment (p < 0.01). From our findings, it could be effective to include air‐classified SFM in early‐phase laying hen diets as an alternative protein source substituting SBM, without negative influence on productive performance and egg traits, reducing also the production costs.     

Effects of Cull Beans,Sunflower Meal,and Canola Meal as Protein Supplements to Beef Steers Consuming Grass Hay on In Situ Digestion Kinetics

Two ruminally cannulated steers were used in an in situ incubation study to test the effects of raw cull Great Northern beans (Phaseolus vulgaris), canola meal, and sunflower meal on rate and extent of digestion of forage DM, NDF, ADF, and N and to compare the DM and N digestibilities of the supplements. Steers were allowed ad libitum access to medium quality grass hay and were assigned in each of five periods to one of five supplemental treatments. The five treatments included: 1) unprocessed Great Northern beans to supply 182 g/d CP (GNB); 2) canola meal to supply 182 g/d CP (CM); 3) a mixture of Great Northern beans and sunflower to each supply 91 g/d CP (MIX); 4) sunflower meal to supply 182 g/d CP (SFM+); and 5) sunflower meal to supply 91 g/d CP (SFM−). Each period consisted of a 7-d adaptation period, 3-d intake period, and 4-d incubation period. Two bags of supplement, two bags of forage, and two blanks were incubated for 0, 4, 8, 12, 18, 24, 36, 48, 72, or 96 h. Treatment had no effect on rate, extent of digestion, or discrete lag time of forage DM, NDF, or ADF (P>0.10). Compared with the SFM+ treatment, forage N degraded at a faster rate when steers were on the GNB (P=0.06), CM (P=0.02), or SFM− (P=0.02) treatments. Forage N in the MIX treatment degraded slower than that in the GNB treatment (P=0.03). No differences (P>0.10) were detected for forage N lag time or extent of digestion. There were no differences in the rate of digestion of supplement DM or N (P>0.80), but canola meal had a greater extent of supplement DM degradation than the sunflower meal from the SFM+ treatment (P=0.13). When supplemented to medium quality hay diets, Great Northern beans, canola meal, or a mixture of Great Northern beans and sunflower meal had similar effects on in situ forage digestion kinetics. Anti-nutritional factors in the beans did not appear to alter rumen digestion of the tested forage.     

In vitro ruminal fermentation and in situ ruminal degradation of tamarind kernel powder extract residue in wethers

We examined the in vitro fermentation characteristics and in situ dry matter (DM) and crude protein (CP) degradability of tamarind kernel powder extract residue (TKPER), a by‐product of polysaccharides thickener processing. Two types of TKPER (I and II), of which the CP and neutral detergent fiber organic matter basis contents (%) were 41.4 and 42.0 and 1.4 and 0.5, respectively, were compared with dry heat soybean (SB), soybean meal (SBM) and dry soybean curd residue (SBCR). The TKPERs had significantly lower in vitro gas production compared to the other products at each observation time (P < 0.05). The in vitro DM and CP digestibility (%) of TKPER I and II were 67.7 and 64.9, and 64.5 and 58.0, respectively, significantly lower than those of SB and SBM (P < 0.05). We used four wethers (55.6 ± 4.6 kg) with ruminal cannulas to investigate the in situ degradability of TKPER I, SB, SBM and SBCR. At the ruminal outflow rate of 0.05/h, the effective degradability (%) values of the DM and CP of TKPER I were 64.1 and 49.7, respectively, which were similar to those of SBM. In conclusion, TKPER had high CP and exhibited in situ degradability similar to that of SBM, suggesting that TKPER could be used as a protein source feed.     

Degradation parameters of amaranth,barley and quinoa in alpacas fed grass hay

This study was conducted to determine the compartment 1 (C1) characteristics of alpacas (fistulated male, 7 ± 1.5 years old, 61 ± 5 kg BW) fed grass hay (GH) supplemented with amaranth (AM), quinoa (Q) and barley (B) grains. Alpacas were provided water ad libitum while housed in metabolism crates. The GH and GH plus treatments were fed at 0700 every day. Treatment periods were for 14 days in which GH or GH plus one of the grain treatments were randomly allocated. On day 14, volatile fatty acids (VFA), pH and ammonia nitrogen (NH₃‐N) were determined at 1, 3, 6, 10, 14, 18 and 24 h post‐feeding. C1 degradation of each feed component was also determined with the alpacas being fed GH only and the samples incubated for 0, 2, 4, 8, 14, 24, 48 and 72 h. Dry matter (DM), neutral detergent fibre (NDF) and crude protein (CP) were determined and were divided into three categories: a = immediately soluble; b = the non‐soluble but degradable; and u = non‐degradable/unavailable, potential extent of degradation (PE), degradation rate (c) and effective degradation (ED). C1 passage rate was determined using acid detergent insoluble ash as a marker and was calculated to be 5.5%?h‐1. Total DM intake was highest (p < 0.05) for B and resulted in a higher (p < 0.05) CP intake. GH and AM were different in mean pH (6.81 and 6.66, respectively). B NH₃‐N was greater (p < 0.05) than the other treatments. Total VFA was greatest (p < 0.05) for AM, with the greatest composition differences being a shift form acetate percentage to butyrate. DM, NDF and CP degradation was different across the treatments, where PE and ED were higher (p < 0.05) for the grain treatments. The pseudo‐grains AM and Q had similar C1 degradation characteristics to B.