Nutritional benefits of specialty grain hybrids in beef feedlot diets

The study of grain hybrids with faster or more extensive rates of ruminal starch fermentation has been a key research area. Because grain sorghum starch is generally regarded as less accessible to enzymatic degradation than starch in other grains, it has received the greatest research emphasis. However, all grains have been evaluated to some extent. Grain sorghum hybrids appear to be more variable in digestibility, in vitro and in vivo, and in rate of starch fermentation than are corn hybrids. The greater variation may be partially because grain sorghum hybrids are developed and evaluated under more stressful environmental conditions (high temperature and limited water conditions) than are corn hybrids. In vitro and in vivo studies indicate that differences in grain hybrids exist, but these differences may not totally explain differences in cattle performance. The response to feeding high-lysine corn to cattle has been variable. Although high-lysine corn supplies more lysine in the diet, lysine flow to the abomasum was not increased. Hybrids selected for increased lysine content have been shown to have faster in vitro rates of starch digestion, suggesting that improvements in animal performance may be related to the indirect selection for improved energy utilization. In one study in which high-oil corn was evaluated, feed conversion was not improved compared with a control corn diet. At the present time additional studies in which other genetic modifications of grain hybrids are evaluated are in progress, but the results have not been published.     

饲喂高淀粉饲粮时不同瘤胃降解淀粉水平对奶牛泌乳性能、营养物质表观消化率和氮平衡的影响

本试验旨在研究饲喂高淀粉饲粮时不同瘤胃降解淀粉水平对奶牛泌乳性能、营养物质表观消化率和氮平衡的影响。选用10头荷斯坦经产奶牛[平均泌乳天数为(214±38)d,平均乳产量为(26.2±2.4)kg/d,平均体重为(727±65)kg]作为试验动物,随机分成2组,每组5头。试验设计2种不同瘤胃降解淀粉水平的试验饲粮,分别为瘤胃降解淀粉水平为62.3%(占总淀粉的百分比)的低瘤胃降解淀粉水平饲粮(L-RDS)和瘤胃降解淀粉水平为72.1%(占总淀粉的百分比)的高瘤胃降解淀粉水平饲粮(H-RDS)。采用交叉试验设计,试验分为2期,过渡期7 d,每期试验21 d,其中适应期14 d,采样期7 d。结果显示:1)相比L-RDS组,H-RDS组有机物和淀粉的表观消化率显著升高(P0.05),中性洗涤纤维和酸性洗涤纤维的表观消化率显著降低(P0.05),干物质表观消化率有升高趋势(P=0.07),蛋白质表观消化率无显著差异(P0.05)。2)相比L-RDS组,H-RDS组尿素氮及它们占摄入氮比例有降低趋势(P=0.09),摄入氮、乳氮、粪氮、尿氮和沉积氮及它们占摄入氮比例无显著变化(P0.05),尿中总嘌呤衍生物排出量和微生物蛋白产量亦无显著变化(P0.05)。3)饲粮瘤胃降解淀粉水平对奶牛干物质采食量、乳产量和乳成分均无显著影响(P0.05)。综合以上结果可知,饲喂高淀粉饲粮时不同瘤胃降解淀粉水平影响饲粮营养物质的表观消化率,对泌乳性能和氮平衡无显著影响。     

The effect of energy supplementation on nitrogen utilization in lactating dairy cows fed grass silage diets

An experiment was conducted to examine the effect that various isoenergetic diets, containing different quantities of soluble carbohydrate and fiber and different types of starch, have on nitrogen (N) balances. Six lactating dairy cows in early to midlactation consuming grass silage diets with not less than 600 g/kg total DMI as forage were used in the experiment. Four concentrates were prepared that had higher amounts of either fiber, soluble sugars, corn (low degradable starch source), or barley (high degradable starch source). Overall N utilization by the cows was poor, rarely exceeding 0.30 g milk N/g of dietary N intake. Fecal N outputs accounted for more than half of total N excreted in all treatments except for diets supplemented with high degradable starch, in which urinary N excretion was significantly higher compared with the other treatments. Milk yield was unaffected by concentrate type, averaging 19.9 kg/d, but milk protein content decreased from 32.9 for starch-based diets to 30.9 and 30.0 g/kg for the soluble sugar- and fiber-based diets, respectively. The efficiency of N utilization improved in the low degradable starch treatment, which had lower N excretion (65%) and higher protein concentration in milk. Furthermore, feeding cows corn-based concentrates reduced urinary N excretion by almost 30% compared with barley-based concentrates; therefore, feeding corn-based diets is recommended for the reduction of nitrogen pollution in lactating dairy cows.     

Utilization of glucose and long-chain fatty acids in lactating dairy cows fed a fat-enriched diet

The fate of carbon from long-chain fatty acids and glucose in dairy cows which were fed with protected fat was studied using stable isotope technique. The experiment was carried out on two groups of dairy cows (n=16 in each group) during the first 15 weeks of the lactation period. The cows were fed isoenergetic and isoproteinogenous diets based on corn silage. About 1.8 kg of tapioca starch in the diet of the starch group was substituted by about 0.7 kg of rumen protected fat (Ca salts of palm oil and soybean oil) in the diet of the fat group. The carbon atoms of dietary fat were naturally depleted in 13C as compared to carbon atoms of starch. Daily milk performance and lactose output were significantly (P < 0.05) higher among the cows fed with fat diet. In comparison to the starch group, the enrichment of milk fat with 13C was significantly lower, while that of breath CO2 was significantly higher in the fat group (P < 0.05). This means the fatty acids were incorporated into milk fat in preference to metabolic oxidation. Further studies showed that blood glucose is oxidized to a lower extent and is used for the synthesis of lactose to a higher proportion if the cows were fed with the fat diet. The glucose entry rate into the body glucose pool was not different between the diets. In conclusion, the dietary fatty acids perform a glucose sparing effect and improve the glucose supply for the mammary gland.     

Effect of anthocyanin‐rich corn silage on digestibility,milk production and plasma enzyme activities in lactating dairy cows

Anthocyanin in purple corn (Zea mays L.) has been reported to show several functional and biological attributes, displaying antioxidant, antiobesity and antidiabetic effects in monogastric animals. The objective of this study was to investigate the effect of feeding anthocyanin‐rich corn (Zea mays L., Choko C922) silage on digestibility, milk production and plasma enzyme activities in lactating dairy cows. The cows were fed diets based on the control corn or the anthocyanin‐rich corn silage (AR treatment) in a crossover design. The anthocyanin‐rich corn silage‐based diet had a lower starch content, nutrient digestibility and total digestible nutrients content when compared to the control diet. The milk yield, lactose and solids‐not‐fat contents in the AR‐treatment cows were lower than in the control cows. The feeding of the anthocyanin‐rich corn silage led to a reduction in aspartate aminotransferase (AST) activity and an increase in superoxide dismutase (SOD) activity in the plasma. These data suggest that the anthocyanin‐rich corn has a lowering effect on AST activity with concomitant enhancement of SOD activity in lactating dairy cows. However, a new variety of anthocyanin‐rich corn with good nutritional value is needed for practical use as a ruminant feed.     

Nutritional strategies to combat physiological imbalance of dairy cows during early lactation: The effect of changes in dietary protein to starch ratios

Abstract

Thirty Danish Holstein cows were used to determine how cows in early lactation adapt to changes in protein to starch supply in order to manipulate metabolism to combat physiological imbalance. During weeks 4 through 6 of lactation, 10 cows were fed either a high protein to starch ratio (high) diet, 10 cows were fed a low protein to starch ratio (low) diet while 10 others continued on the control diet. During weeks 7 through 9 of lactation, all cows returned to the control diet. The diets were formulated to consist of 15.0%, 18.6% and 22.2% crude protein and 13.3%, 7.5% and 1.7% of starch for the low, control and high diets, respectively. Besides milk urea nitrogen, no other production or metabolic parameters were affected by treatment. In conclusion, manipulation of dietary protein to starch is not a potential strategy to combat physiological imbalance during early lactation.     

小麦在奶牛日粮中的应用研究进展

本文将小麦与玉米的营养价值作比较,对小麦在奶牛日粮中的应用研究现状进行了综述,探讨其在奶牛日粮中替代玉米的可行性,旨在为小麦的合理开发利用和研究奠定基础。     

蒸汽压片处理谷物对奶牛生产性能的影响

谷物加工主要有干碾压、蒸汽碾压和蒸汽压片处理三种方法。蒸汽压片处理是提高谷物淀粉消化率的最有效的途径。生产中采用该法处理谷物对提高奶牛生产性能有现实意义。     

Effects of Forage Species on Milk Protein Production by Lactating Dairy Cows

Eighteen multiparous early lactation Holstein cows were assigned to a replicated 3 × 3 Latin square with 28-d periods to evaluate milk protein production potential when corn silage (CS) or small grain silage (SGS) was added to diets based on alfalfa silage (AS). Treatments consisted of all AS, a mixture of AS and CS, or a mixture of AS and SGS. Treatment diets were isonitrogenous, isofibrous, and contained maximal amounts of carbohydrates to challenge the milk protein production of cows under intensive milk production systems fed these forages. Lactation performance, milk composition, nutrient intakes, and diet digestibilities were measured. There were no significant differences in milk yield of the cows fed diets containing AS, CS, or SGS. Cows fed diets containing all AS-produced milk with a higher fat percentage than did cows fed CS, and cows fed diets containing all AS produced more milk fat and protein than cows fed CS or SGS. There were no significant differences in the percentage of casein, whey protein, or true protein in milk when cows were fed AS, CS, or SGS. There were also no significant differences in the percentage or production of lactose or solids-not-fat when cows were fed diets containing different silages. Similarly, there were no significant differences in DMI or dietary DM digestibility by cows when fed diets containing different silages. Data suggest that adding CS or SGS to AS-based diets does not improve DMI, lactation performance, or milk protein production of lactating cows.     

ORIGINAL ARTICLE: Effects of long‐term feeding of genetically modified corn (event MON810) on the performance of lactating dairy cows

A long‐term study over 25 months was conducted to evaluate the effects of genetically modified corn on performance of lactating dairy cows. Thirty‐six dairy cows were assigned to two feeding groups and fed with diets based on whole‐crop silage, kernels and whole‐crop cobs from Bt‐corn (Bt‐MON810) or its isogenic not genetically modified counterpart (CON) as main components. The study included two consecutive lactations. There were no differences in the chemical composition and estimated net energy content of Bt‐MON810 and CON corn components and diets. CON feed samples were negative for the presence of Cry1Ab protein, while in Bt‐MON810 feed samples the Cry1Ab protein was detected. Cows fed Bt‐MON810 corn had a daily Cry1Ab protein intake of 6.0 mg in the first lactation and 6.1 mg in the second lactation of the trial. Dry matter intake (DMI) was 18.8 and 20.7 kg/cow per day in the first and the second lactation of the trial, with no treatment differences. Similarly, milk yield (23.8 and 29.0 kg/cow per day in the first and the second lactation of the trial) was not affected by dietary treatment. There were no consistent effects of feeding MON810 or its isogenic CON on milk composition or body condition. Thus, the present long‐term study demonstrated the compositional and nutritional equivalence of Bt‐MON810 and its isogenic CON.     

Carbohydrate nutrition.

An understanding of carbohydrate nutrition is essential to optimize production of dairy cattle. Two rations, both of which appear to be balanced, may have dramatically different results when fed to high-producing dairy cattle. Carbohydrates directly affect microbial protein production and therefore protein nutrition of dairy cattle. Energy intake can be maximized by considering the amount and type of carbohydrate in the ration: 1. The fiber level of the ration should be evaluated. NDF levels should be between 25 and 30% for high-producing cows in early lactation. Within this range, less fiber is required with adequate forage particle length and high frequency of grain feeding, and when buffers are fed and slowly fermented NSC sources are included in the ratio. For mid- and late-lactation cows, fiber levels are higher, ranging between 30 and 36% NDF depending upon the energy required to support milk production and restoration of body condition. 2. Provide adequate effective fiber. There should be some forage particles 1.5 in long in the ration. Limit most high-fiber byproducts to 25% of fiber requirements. 3. Feed highly digestible fiber sources. Differences in fiber digestibility of 30% will result in over 4 Mcal of NEL per day with 15 lb NDF intake. In addition, highly digestible fiber has less gut fill effect, possibly increasing dry matter intake. 4. Consider site of starch digestion. Slowly degraded starch sources such as sorghum may require steam flaking to increase ruminal fermentation. Other situations may require the addition of a slowly degraded starch source. 5. Increase frequency of concentrate feeding. Feed grain at least four times per day or include in a total mixed ration. 6. Include buffers. Under some situations (corn silage, early lactation) buffers allow more grain to be fed. 7. Add fat. Fat supplementation to milking cows has become a common practice in high-producing herds. Fat has about three times the energy of cracked corn and is often used to replace a portion of the grain to increase the energy density of the ration. It is important to realize that fat can cost up to two to three times more per megacalorie of energy than grain. Before fat is added to the ration, less expensive ways to increase energy density (listed previously) should be thoroughly explored.     

Milk production,nutrient digestibility and nitrogen balance in lactating cows fed total mixed ration silages containing steam‐flaked brown rice as substitute for steam‐flaked corn,and wet food by‐products

The objective of this study was to evaluate the effect of substituting brown rice grain for corn grain in total mixed ration (TMR) silage containing food by‐products on the milk production, whole‐tract nutrient digestibility and nitrogen balance in dairy cows. Six multiparous Holstein cows were used in a crossover design with two dietary treatments: a diet containing 30.9% steam‐flaked corn (corn TMR) or 30.9% steam‐flaked brown rice (rice TMR) with wet soybean curd residue and wet soy sauce cake. Dietary treatment did not affect the dry matter intake, milk yield and compositions in dairy cows. The dry matter and starch digestibility were higher, and the neutral detergent fiber digestibility was lower for rice TMR than for corn TMR. The urinary nitrogen (N) excretion as a proportion of the N intake was lower for rice TMR than for corn TMR with no dietary effect on N secretion in milk and fecal N excretion. These results indicated that the replacement of corn with brown rice in TMR silage relatively reduced urinary N loss without adverse effects on feed intake and milk production, when food by‐products such as soybean curd residue were included in the TMR silage as dietary crude protein sources.     

Nutrients,amino acid,fatty acid and non‐starch polysaccharide profile and in vitro digestibility of macadamia nut cake in swine

The highly variable cost and limited availability of conventional feedstuffs make it imperative to explore alternative feedstuffs to be used in swine. Macadamia nut cake (MNC), a coproduct of the macadamia nut oil industry, has not been well studied. MNC was analyzed for its nutrient profile, gross energy (GE), fibers, amino acids and fatty acids content. Dry matter (DM) and GE digestibility of MNC in swine was determined using an in vitro model. On a DM basis, ash, crude protein, ether extract, NDF, ADF, lignin and GE were found to be 3.7, 25.5, 11.9, 35.8, 28.0, 16.0% and 5581 kcal/kg, respectively. Total and soluble non‐starch polysaccharide content were 32.2 and 11.8%, respectively. The concentration of lysine was found to be 0.7%. The DM and GE digestibility were found to be 75.7 and 71.4%, respectively. Gross energy content of MNC is comparable with that of corn and higher than soybean meal, while protein content is twice as high as corn but lower than soybean meal. In conclusion, MNC is not merely a good source of protein and energy but also has fairly high digestibility in swine. Hence, it can be used as a viable alternative source of energy and protein in swine diets.     

Starch levels on performance,milk composition and energy balance of lactating dairy cows

The objective of this experiment was to evaluate the effects of starch levels in diets with the replacement of citrus pulp for corn on milk yield, milk composition, and energy balance of lactating dairy cows. Twenty-eight multiparous Holstein cows were used in seven 4?×?4 Latin squares conducted concurrently, and each experimental period consisted of 20 days (16 days for adaptation and 4 days for sampling). The experimental treatments comprised four starch levels: 15, 20, 25, and 30 % in the diet. The dry matter intake increased linearly with increasing starch levels. The milk yield and 3.5 % fat-corrected milk yield showed quadratic response to increasing starch levels. The milk protein content and milk total solids content responded linearly to increasing starch levels. The feed efficiency, milk lactose content, milk urea nitrogen, plasma urea nitrogen, and plasma glucose concentration were not affected by starch levels. The estimated net energy for lactation (NE_L) intake increased linearly as the starch level was raised. Although the milk NE_L output per kilogram of milk was not affected by starch, the milk NE_L output daily responded quadratically to starch levels. In addition, the NE_L in body weight gain also responded quadratically to increasing starch levels. The efficiency of energy use for milk yield and the NE_L efficiency for production also responded quadratically to increasing starch levels. Diets for mid-lactating dairy cows producing around 30 kg/day of milk should be formulated to provide around 25 % starch to optimize performance.

     

Supplemental fat in high-energy rations for lactating cows: effects on intake, digestion, milk yield, and composition

Supplemental fats (SF) have special value in the diets of dairy cows with superior productive ability, because the high energy density of SF allows greater energy consumption and direct transfer of the fatty acids (FA) of the SF to milk fat; this increases metabolic efficiency. Some SF, especially oils with a high degree of unsaturation, disturb ruminal fermentation, decrease fiber digestibility, and lower milk fat test; however, oilseeds (e.g., whole cottonseed) can be fed without observable ruminal inhibition, probably because of a slow release of the oil into ruminal contents. A number of commercial fat supplements are available that have little effect on ruminal fermentation and are highly digestible postruminally. A product of the calcium salts of palm oil fatty acids was shown to have a NE for lactation of more than three times that of corn. As the emphasis in milk pricing formula changes from milk fat to milk protein, there is greater concern regarding the propensity of fat supplements to decrease milk protein (casein) percentage. In two studies, a supplement of ruminally protected lysine and methionine largely prevented the reduction in casein percentage that occurred with feeding SF, indicating that the amino acid profile of undegraded dietary protein is important with regard to preventing the lower casein percentage. Combining fat supplements that are slowly released in the rumen with those that are inert in the rumen will allow maximal use of SF.     

Utilization of Bt corn residues by grazing beef steers and Bt corn silage and grain by growing beef cattle and lactating dairy cows

Three experiments were conducted to evaluate the impact of the Bacillus thuringiensis (Bt)-11 transformation event in two parental corn hybrids differing in date of maturity on beef and dairy cattle performance. Sixteen lactating Holstein dairy cows in replicated 4 x 4 Latin squares were assigned to four diets in a 2 x 2 factorial arrangement: Bt vs non-Bt trait and early- vs late-maturing corn hybrids. The diets contained 40% of the test corn silage plus 28% corn grain from the same corn hybrid (DM basis). There was no effect of the Bt trait on efficiency of milk production, ruminal pH, acetate:propionate ratio, or in situ digestion kinetics of NDF. The early-maturing corn hybrids resulted in greater total VFA concentrations in the rumen and efficiency of 4% fat-corrected milk production than the later-maturing hybrids (P < 0.05). Sixty-seven steer calves were used in a 70-d corn residue grazing trial for the late-maturing corn hybrids only. Daily BW gain of steers was similar for those grazing Bt and non-Bt corn residues, and the steers exhibited no grazing preference between Bt and non-Bt corn residue. One hundred twenty-eight steer calves were assigned to four silage-based growing diets in a 2 x 2 factorial arrangement: Bt vs non-Bt trait and early- vs late-maturing corn hybrids. The diets contained 90% corn silage and 10% supplement (DM basis). The DMI was higher for steers fed Bt compared with non-Bt hybrids (P < 0.02). An interaction (P < 0.03) was observed for feed efficiency between hybrid genotype and incorporation of the Bt trait. Feed efficiency was greater (P < 0.05) for steers fed the later-maturing non-Bt hybrid compared with the later-maturing Bt hybrid; however, feed efficiency was similar between steers fed early-maturing Bt and non-Bt corn silages. Steers fed the early-maturing hybrid gained 11% faster and were 7% more efficient compared with those fed the late-maturing hybrid. These latter results agree with the dairy experiment in which the early-maturing hybrid resulted in 5% greater efficiency of milk production than the later-maturing corn hybrid. In all experiments, incorporation of the Bt trait into corn had no consistent effect on cattle performance. In addition, background genetics of the corn hybrids appeared to have a more consistent impact on performance than did presence of the Bt trait.     

奶牛低淀粉型日粮研究进展

低淀粉型日粮的应用不仅可以满足高产奶牛生产阶段的能量需要,而且可以保证奶牛瘤胃健康,避免瘤胃酸中毒。常用低淀粉型饲料有优质牧草、中性洗涤可溶性纤维源饲料以及可溶性糖三大部分。饲喂低淀粉型日粮可以有效缓解挥发性脂肪酸的产生,避免瘤胃pH降低,并促进了奶牛的采食以及养分消化,提高乳品质。本文从低淀粉型日粮的实现手段,以及瘤胃发酵参数和生产性能方面阐述低淀粉型日粮在奶牛生产中的必要性,确立今后的研究重点应该在各种原料替代谷物原料的最适比例及组合效应方面,从而完善奶牛低淀粉型日粮配制技术。     

Balancing diets for physically effective fibre and ruminally degradable starch: A key to lower the risk of sub-acute rumen acidosis and improve productivity of dairy cattle

Finding an optimal balance between the amount of physically effective fibre and rumen fermentable carbohydrates in the diets of high-producing dairy cows is difficult, but critical to prevent sub-acute ruminal acidosis (SARA), optimize digestion, nutrient utilization, and improve productivity. The main aim of the present review was to provide a summary of recent achievements regarding the role that interactions between dietary factors such as grain fermentability and physically effective neutral detergent fibre (peNDF) have on rumen fermentation and SARA as well as on production performance in high-producing dairy cows. The review first considers factors related to grain fermentability and finds that the latter variable depends mainly on the source of starch as well as in processing and conservation method; however, dairy cow's response to grain fermentability should be considered in relation with the total amount of starch and/or concentration of peNDF in the diet. Forages and current methods used in the evaluation of their physical characteristics were also reviewed suggesting the use of Penn State Particle Separator as an adequate approach to determine the distribution of particle fractions as well as the content of peNDF in both forages and total mixed rations. Furthermore, results reviewed in this study suggest that a content of peNDF_> 1.18 (expressed inclusive of particles-dry matter > 1.18 mm) in the diet of about 30–32% is sufficient in maintaining a daily mean of ruminal pH of 6.2, lowering the risk of SARA, and preventing milk fat depression without exerting any negative effects on daily feed intake and milk production. The review concludes with a practical recommendation in terms of balancing diets with peNDF_> 1.18 and ruminally degradable starch, suggesting that a ratio between the two variables lower than 1.45 should be avoided when formulating diets for lactating dairy cows.     

甘蔗渣作为粗饲料对奶牛生产性能、养分消化和采食行为的影响

文章旨在评价甘蔗渣作为粗饲料对泌乳奶牛采食量、消化率、采食行为、泌乳量、乳成分及微生物蛋白合成等方面的影响。试验选择10头初始体重为(450±25.6)kg,泌乳天数为(143.7±30.7)d的杂交奶牛为研究对象,试验采用5×5拉丁方设计,饲喂周期为5个21 d(1~14 d为适应期,15~21 d为数据采集期)。试验日粮分为对照日粮、45%、50%、55%和60%甘蔗渣日粮。结果:对照组与45%和50%甘蔗渣组干物质、有机物、总可消化养分摄入量、干物质和有机物消化率无显著差异(P>0.05),而55%和60%甘蔗渣组干物质和有机物消化率最低(P<0.05)。甘蔗渣组与对照组对中性洗涤纤维摄入量和表观消化率的影响具有显著差异(P<0.05),其中45%甘蔗渣组奶牛的非纤维碳水化合物摄入量和消化率与对照组相似(P>0.05)。日粮甘蔗渣添加水平对营养物质的摄入量和消化率呈显著线性降低(P<0.05)。60%甘蔗渣组较对照组显著降低了奶牛反刍时间,显著提高空闲时间(P<0.05)。奶牛的反刍时间、反刍和采食效率随日粮甘蔗渣添加水平的升高显著线性降低(P<0.05),而空闲时间随饲粮中甘蔗渣含量的增加线性增加(P<0.05)。结论:日粮添加甘蔗渣降低了奶牛日产奶量,但添加水平为45%~50%时可以使奶牛泌乳量达到12 kg/d。