Long-term feeding of acetyl urea to dairy cows

After an introductory survey of investigations dealing with the conversion of acetyl urea in the ruminant organism, a feeding trial using dairy cattle is described in which the effects of long-term acetyl urea feeding on the clinical picture and various performance parameters have been studied. Five Black-Pied cows of medium milk yield were fed a natural diet and received, over at least 14 months, a daily acetyl urea supplementation of 430 g (= 40 to 44% of the digestible crude protein). The clinical control, including the analysis of blood parameters, did not produce any deviation from normal. As to milk and butterfat yields, the experimental group reached results comparable to those of the control group. Over the entire experimental period the experimental group and the control averaged per cow and day of milking 11.1 and 11.3 kg FCM, respectively. The reproductive behaviour proved normal for all the cows under study. Postmortem findings of 4 cows revealed, among other things, chronic kidney alterations that cannot be safely exluded to be caused by the experiments. A stress over several months of two cows fed 850 g acetyl urea per day was not found to affect animal performance and health.     

甜高粱饲用价值及饲喂奶牛技术

近年来我国畜牧业发展迅速,奶牛存栏数量呈现逐年增加的趋势,与此同时,人们对各类奶制品需求量的逐渐增加,进一步带动了以奶牛业为核心的畜牧业发展。目前一些大型畜牧场将玉米(Zea mays)饲草作为畜禽的主要饲料,远不能解决畜牧业快速发展导致的饲草不足问题。甜高粱(Sorghum bicolor)是一种仅次于青贮玉米的优良饲草作物,耐干旱,耐贫瘠,生物产量高,籽粒可以用作配合饲料,茎叶和秸秆可进行青饲、青贮等。本文从甜高粱的刈割、甜高粱不同预处理方式及甜高粱的多功能用途等方面进行综述,对甜高粱饲喂奶牛的效果进行综合对比,并提出饲用应注意事项等,旨在为今后使用甜高粱饲喂奶牛提供一些技术参考。     

过硫酸钾对麦秸营养价值及其瘤胃有效降解率的影响

分别用 0 5 %过硫酸钾 (B)、1 %过硫酸钾 (C)、2 %过硫酸钾 (D)、4 %尿素 (E)处理麦秸 ,A为对照组 ,水分调至 4 5 % ,密封保存 2 0d ,然后利用瘤胃尼龙袋法测定麦秸有效降解率 ,分析相关营养指标。结果表明 ,过硫酸钾可显著降低 (P <0 0 5 )NDF含量 ,B、C、D三个处理组分别比对照组降低 3 2 0 %、6 90 %和 1 0 79% ;4 %尿素处理麦秸后 ,麦秸DM中CP含量极显著 (P <0 0 1 )提高 ,比对照组提高 1 63 1 9% ,NDF含量显著降低 (P <0 0 5 ) ,比对照组降低 5 3 8%。用过硫酸钾处理麦秸 ,可极显著地 (P <0 0 1 )提高麦秸DM、OM、NDF有效降解率 ,以 2 %过硫酸钾处理麦秸效果最好 ,可分别提高麦秸DM、OM、NDF有效降解率 2 9 5 9%、3 0 76%和 3 0 5 7% ;4 %尿素可极显著地 (P <0 0 1 )提高麦秸DM、OM、NDF有效降解率 ,分别提高 2 6 73 %、2 7 2 9%和 1 1 74 % ;2 %过硫酸钾稍优于 4 %尿素处理麦秸的效果 ,二者差异不显著 (P >0 0 5 ) ,但在提高NDF降解率方面 ,2 %过硫酸钾极显著(P <0 0 1 )优于 4 %尿素处理麦秸的效果     

Influence of urea molasses treated wheat straw fermented with cattle manure on chemical composition and feeding value for growing buffalo calves

The study was conducted to examine the chemical composition of urea–molasses treated wheat straw (WS) fermented with cattle manure (CM) and its feeding value for growing buffalo male calves. Wheat straw treated with varying levels of urea (0%, 2% and 4%) and molasses (2% and 4%) was ensiled with 30% cattle manure (on dry matter basis) for different fermentation periods (20, 30 and 40 days). Fermented wheat straw (FWS) after each fermentation period was analyzed for pH, dry matter (DM), crude protein (CP), true protein (TP), ammonia nitrogen (NH₃-N), acid detergent fiber (ADF) and neutral detergent fiber (NDF). Maximum pH, DM, CP, TP and NH₃-N and minimum NDF contents were observed with 4% urea. The 4% molasses level increased the CP, TP and NH₃-N contents of FWS, but pH, DM and NDF remained unchanged after 40 days of fermentation. The 4% urea × 4% molasses interaction resulted in maximum DM, CP, TP, NH₃-N after 40 days of fermentation period and this combination was used for large scale production of FWS to evaluate its feeding value for calves. Four isonitrogen and isocaloric diets were formulated. The control FWS 0 diet contained no FWS while in FWS 15, FWS 25 and FWS 35 diets concentrate was replaced with 15%, 25% and 35% FWS, respectively. The diets were randomly allotted to four groups of 28 calves 9–12 months of age, seven in each group, in a randomized complete block design to examine the nutrient intake, digestibility, nitrogen balance and weight gain. An increased DM, organic matter (OM), CP and NDF intakes were observed in calves fed FWS diets compared to those fed FWS 0 diet. Nitrogen retention increased significantly with increasing the level of FWS. The DM, OM, CP and NDF apparent digestibilities were non-significant in calves fed different levels of FWS. A linear increase in weight gain was noticed in calves fed diets containing increasing level of FWS.     

Some attempts to improve the nutritive value of urea for dairy cows. 3. Its adjunction to fermentable carbohydrates: starea

Starea, an intimate mixture of gelatinized wheat starch and urea, was tested again urea with regard to the ammonia release in the rumen, the amount and composition of the nitrogen fraction reaching the intestine, the nitrogen and energy balances, and the performance of lactating cows. Maize silage was the basal feed in all experiments. The ammonia concentration in the rumen liquor was measured in two cows fitted with a permanent rumen cannula. The curve of the ammonia concentration was about the same with both nitrogen supplements, and peaked at about 250 mg/l (14.7 mmol/l) two hours postfeeding. Two dry cows fitted with a re-entrant cannula at 10 cm from the pylorus were fed with maize silage supplemented with increasing amounts of either urea or starea. The duodenal nitrogen flow rapidly levelled off with both supplements and no significant difference between them could be detected. The amount of ammonia in the duodenal digesta remained very low. Nitrogen digestibility measured in lactating cows was not noticeably affected when starea instead of urea was added to maize silage. However, nitrogen excretion in the urine tended to decrease, while nitrogen secretion in milk was augmented with starea. The digestibility of the rations and their metabolizable energy supply were not significantly affected, and milk production was quite the same with both supplements, apart from the higher amount of milk protein obtained with starea compared with urea. As a general conclusion from the whole work conducted on the nutritive value of urea for lactating cows, it can be stated that the decline in performance of the animals after substitution of urea for conventional protein is mainly due to a decrease of the metabolizable energy concentration in the diets. None of the attempts tested in an effort to improve the nutritive value of urea was able to overcome this difficulty.     

酵母培养物对奶牛干物质采食量、产奶量及血清指标的影响

试验旨在研究纽润康酿酒酵母培养物对奶牛的干物质采食量、产奶量及血清指标的影响。试验组和对照组各300头奶牛,对照组奶牛饲喂基础日粮,试验组奶牛在基础日粮基础上添加120 g/(头·d)酿酒酵母培养物。结果显示,试验组奶牛产奶量显著提高1.66 g/(头·d),平均干物质采食量显著提高0.72 g/(头·d)。试验组奶牛血清中谷丙转氨酶活性极显著低于对照组(P<0.01),血清免疫球蛋白G (IgG)含量极显著高于对照组(P<0.01)。日粮中添加酵母培养物能够极显著提高超氧化物歧化酶(SOD)活性(P<0.01),显著提高奶牛机体的总抗氧化能力(T-AOC)(P<0.05)。研究表明,日粮中添加酿酒酵母培养物可提高奶牛机体的免疫力和抗氧化能力。     

氢氧化钙与尿素复合处理对小麦秸营养品质的影响

通过化学成分分析、活体外消化率测定和绵羊饲养试验，研究了2％尿素与氢氧化钙复合处理对小麦秸营养价值的影响。结果表明，秸秆中氮保留率直接受氢氧化钙的影响（P〈0．01），氢氧化钙大于6％时，氮保留率可达到98％。2％尿素和氢氧化钙复合处理，氢氧化钙为4％时，提高营养价值效果与单纯6％尿素处理相当；氢氧化钙为6％时，效果与4％NaOH处理相当。羊的饲养试验表明，2％尿素和6％氢氧化钙复合处理小麦秸效果最好。     

饲料中添加干酵母对奶牛生产性能的影响

选用20头胎次、泌乳月、产奶量、乳成分及身体状况相似的高产荷斯坦奶牛,随机分为2组.试验组奶牛每天添加2 g/(d·头)高活性干酵母,研究其时奶牛生产性能的影响.结果表明:饲料中添加高活性干酵母能使奶牛产奶量显著增加(PO.05).     

复合酵母培养物对奶牛生产性能的影响

<正>近年来,国内外有很多关于酵母培养物在奶牛生产中应用的研究,在日粮中添加酵母培养物可以稳定瘤胃内环境,促进有益菌群的增殖(张连忠,2009),同时     

Effects of urea treatment of straw and dietary level of vegetable oil on lactating dairy cows

Four crossbreds (75% Holstein Friesian) lactating dairy cows were used to evaluate the effects of sunflower oil (SFO) levels and roughage source on feed intake, nutrient digestibility, ruminal fermentation, milk yield, and milk composition. Four milking cows with average liveweight of 410 ± 25 kg and 18 ± 11 days in milk were randomly assigned according to a 4 × 4 Latin square design, in a 2 × 2 factorial arrangement, with SFO levels (3% or 6%) in the concentrate and the roughage source [rice straw (RS) or urea-treated RS (UTRS)] being the main factors. Four dietary treatments as (1) 3% SFO + RS, (2) 6% SFO + RS, (3) 3% SFO + UTRS, and (4) 6% SFO + UTRS were offered ad libitum total mixed ration, with a concentrate/roughage ratio of 60:40. The results were found that UTRS as a roughage source significantly increased feed intake, digestibility, concentration of acetic acid in rumen fluid, rumen ammonia–nitrogen, blood–urea nitrogen, milk urea–nitrogen, and milk yield (3.5% fat-corrected milk) compared with cows fed on untreated RS. Supplementation of SFO at 3% in the concentrate-supplemented group having increased dry matter intake, milk fat percentage, and milk yield (3.5% fat-corrected milk) compared with 6% SFO supplementation. However, there were no interaction effects between level of SFO in the concentrate and roughage source in any of the factors studied.     

Feeding value of urea molasses-treated wheat straw ensiled with fresh cattle manure for growing crossbred cattle calves

The study was carried out to evaluate the influence of urea plus molasses-treated wheat straw (WS) ensiled with cattle manure (CM) on nutrients intake, their digestibilities, and growth performance of crossbred (Sahiwal × Holstein Friesian) cattle calves. The CM was mixed with ground WS in a ratio of 30:70 on dry matter (DM) basis. The WS–CM mixture treated with urea (4% DM) and molasses (4% DM) was allowed to ferment for 40 days in a cemented pit. Four iso-nitrogenous and iso-energetic fermented wheat straw (FWS)-based experimental diets were formulated. The FWS0, FWS20, FWS30, and FWS40 diets contained 0%, 20%, 30%, and 40% FWS, respectively. Twenty calves (9–10 months of age) were randomly allocated to four dietary treatments in a randomized complete block design, five in each group. Increasing trends for DM, organic matter, crude protein, and neutral detergent fiber intakes by calves were observed with increasing dietary FWS level. Weight gain was significantly different among calves fed different levels of FWS. The highest weight gain (491.8 g/day) was observed in calves fed FWS40 diet, while calves fed FWS0 and FWS20 diets gained 350.0 and 449.6 g/day, respectively. The results from this study imply that the FWS can be added up to 30% in the diet of growing crossbred calves without any detrimental effect on their performance.     

稻草加酶青贮饲喂育成牛的效果研究

本研究以新鲜晚稻草为原料，探讨了添加Ｓｔｒａｗｚｙｍｅ酶制剂对青贮晚稻草发酵品质和育成牛生产性能的影响。试验设３个处理，试验１组每吨稻草（ＤＭ）加酶８００克和麸皮５０千克；试验２组每吨稻草加酶８００克；对照组只加水调制。各处理和２组的采食量分别对照组高５８．６％，３２．２％；日增重分别比对照组高３４．３％和１１．８％。青贮晚稻草中添加Ｓｔｒａｗｚｙｍｅ可以改善青贮晚稻草的发酵品质，提高营养价值。     

高纤维副产品饲料饲喂奶牛的营养特性分析

饲料资源短缺会影响我国饲料加工业和畜牧业的持续健康发展。因此,充分了解各种农副产品的营养特性,并将其应用于生产中,可缓解我国饲料资源短缺。本文针对高纤维副产品饲料饲喂奶牛的营养特性作一分析。1甜菜渣甜菜渣来自清洗干净且去掉顶部、叶子制糖甜菜的干缩残渣。甜菜渣适口性好,其营养成分见表1。甜菜渣饲喂奶牛的最高上限约是精料的一半,即每头牛3.63～6.72kg/d(DM)。甜菜渣和带皮玉米分别含有39%和75%非纤维性碳水化合物(NFC),且大部分NFC是果胶物质,有助于瘤胃中乙酸盐产生,它还可以用于提供日粮中可发酵纤维物质,降低奶牛日…     

Economic value of urea-treated straw fed to lactating buffaloes during the dry season in Nepal

Summary An experiment was conducted to study the effects of feeding urea-treated rice straw to lactating buffaloes in the Koshi Hills. Six pairs of similar buffaloes on farms were selected. All were given a conventional diet based on rice straw for four weeks, then one of each pair was given 15 to 20 kg/day of urea-treated rice straw for a period of four weeks while the control group received untreated rice straw. In the final four week period all animals were given the conventional diet. Feeding straw treated with 4% urea increased the voluntary intake of straw by 25% and increased milk yield by 1·6 litres/day compared with buffaloes fed the conventional diet containing untreated straw. Milk production remained elevated after the four-week treatment period had finished. The results show that buffalo cows fed urea-treated straw achieved better weight gain, and milk yield increased significantly (P<0·01) compared with the control animals. During the treatment period the net benefit was 4·0 (i.e. US$ 0·16) Nepalese currency rupees (NCRs) per day and the incremental rate of return was 46 per cent. Moreover, in the four weeks following the treatment period the net benefit was 10·0 NCRs (i.e. US$ 0·40) per day. Ensiling rice straw with 4% urea can be recommended as a safe, economical and suitable method for improving the nutritional value of rice straw on small farms in Nepal thus increasing milk production and liveweight of lactating buffaloes. The practice of feeding urea-treated straw is economic for farmers during the dry season from January to April. It is urged that urea be made available in villages through the Agricultural Inputs Corporation, local co-operatives and private dealers.

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Resumen Se condujo un experimento para estudiar el efecto de alimentar búfalos en lactación, con paja de arroz tratada con urea, en las monta?as de Koshi. Se seleccionaron seis pares de búfalos en algunas fincas. Todos los animales recibieron una dieta convencional con base en paja de arroz sin tratar, durante cuatro semanas. Seguidamente se suministró de 15 a 20 kg/dia de paja tratada con urea a un animal de cada pareja, recibiendo los animales controles paja sola sin tratar. Durante las cuatro semanas finales, todos los animales recibieron la dieta convencional. La alimentación con paja tratada con urea al 4%, incrementó el consumo voluntario 25% e incrementó la producción de leche 1·6 litros/día, comparado con los búfalos controles. La producción de leche permaneció elevada, después del suministro de paja tratada con urea durante cuatro semanas. Los resultados demuestran, que las vacas búfalo que recibieron la dieta experimental aumentaron de peso y produjeron más leche (P<0·01), que los animales controles. Durante el período de tratamiento, el beneficio neto fue de 4·0 (US$ 0·16) rupíes nepaleses diarios y la tasa de retorno incremental fue de 40 por ciento. Más aún, en las cuatro semanas después del tratamiento, el beneficio neto fue de 10·0 rupíes nepaleses (US$ 0·40) diarios. El ensilaje de paja de arroz con urea al 4% puede recomendarse como una tecnología segura y económica, para incrementar el valor nutricional de la paja de arroz en granjas peque?as en Nepal, incrementando así el peso y producción de leche en vacas búfalo. Esta práctica es económica para granjeros durante los meses de sequía, de enero hasta abril. Se sugiere en este trabajo, que se promueva el suministro de urea en villorrios, a través de la Corporación de Insumos Agrícolas, cooperativas locales y comerciantes privados.

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Résumé Une expérience a été réalisée pour étudier les effets d'une alimentation de paille de riz traitée à l'urée chez des bufflesses en lactation des collines de Koshi. 6 paires homogènes ont été sélectionnées. Toutes ont re?u un régime alimentaire conventionnel à base de paille de riz pendant 4 semaines, puis un animal de chaque paire a re?u 15 à 20 kg par jour de paille de riz traitée à l'urée pendant une nouvelle période de 4 semaines. Dans le même temps, les animaux témoins n'ont re?u que de la paille de riz non traitée. Enfin, pendant la phase terminale (4 semaines), les animaux ont à nouveau re?u une alimentation classique. Le régime à base de paille traitée avec 4% d'urée a accru de 25% l'ingestion volontaire de paille et de 1,6 l/j le rendement laitier, par rapport à celui des animaux nourris avec une ration ne contenant pas de paille traitée. La production de lait est restée élevée après la fin de la période expérimentale de traitement de 4 semaines, les résultats montrent que les bufflesses nourries à la paille traitée ont un gain de poids plus élevé et une augmentation significative de leur rendement laitier (P<0,01) comparés à ceux des animaux témoins. Pendant la période de traitement, le bénéfice net quotidien exprimé en monnaie népalaise a été de 4,0 roupies, (soit 0,16$US), et l'accroissement du taux de rendement a été de 46%. De plus, durant les 4 semaines suivant la période de traitement à l'urée, le profit net quotidien a été de 10,0 roupies népalaises soit 0,40 $US). On peut recommander l'ensilage de la paille de riz avec 4% d'urée comme une méthode s?re, économique et adaptéc pour améliorer la valeur alimentaire de la paille de riz dans les petites exploitations népalaises et donc, pour accro?tre le poids vif et la production laitière des bufflesses en lactation.

     

Improving the nutritive value of cassava bioethanol waste using fermented yeast as a partial replacement of protein source in dairy calf ration

Tropical Animal Health and Production - The aim of this work was to evaluate the influence of yeast (Saccharomyces cerevisiae)–fermented cassava bioethanol waste (YECAW) on feed utilization,...     

Effects of treating rice straw with urea or urea and calcium hydroxide upon intake, digestibility, rumen fermentation and milk yield of dairy cows

Three, multiparous Holstein crossbred dairy cows with initial body weight of 385 ± 19 kg were randomly allocated to 3 treatments of rice straw (T1 = untreated rice straw; T2 = 5.5% urea-treated rice straw (5 g urea in 100 ml water to 100 g air-dry (91% DM) straw); T3 = 2.2% urea + 2.2% calcium hydroxide treated rice straw (2.0 g urea and 2.0 g Ca(OH)₂ in 100 ml to 100 g air-dry (91% DM) straw) according to a 3 × 3 Latin square design. Each period lasted for 21 days in which feed, feces and rumen fluid were collected during the last 7 days for chemical analyses. The findings revealed significant improvements in dry matter intake and digestibility by using 5.5% urea-treated rice straw and 2.2% urea + 2.2% calcium hydroxide treated rice straw. Ruminal pH and NH₃-N were found higher (P < 0.05) as compared with urea-treated rice straw fed group, while blood urea nitrogen and milk urea nitrogen were in normal ranges. Volatile fatty acid concentrations especially those of acetic acid were decreased (P < 0.05) and those of propionic acid were increased (P < 0.05), thus acetic acid:propionic acid was subsequently lowered (P < 0.05) in cows fed with 5.5% urea-treated rice straw and 2.2% urea + 2.2% calcium hydroxide treated rice straw, respectively. Moreover, ruminal viable and cellulolytic bacterial counts were enhanced by urea and calcium hydroxide treatments. Milk protein and fat concentrations were additionally increased by respective treatments while 3.5% fat-corrected milk was highest; ranking from 2.2% urea + 2.2% calcium hydroxide treated rice straw, 5.5% urea-treated rice straw and urea-treated rice straw fed groups. Based on this study, implications could be made that using 2.2% urea + 2.2% calcium hydroxide treated rice straw for straw treatment could be an alternative treatment to 5.5% urea treatment with regards to its effectiveness and treatment cost for lactating dairy cows.     

Some attempts to improve the nutritive value of urea for dairy cows. II. Its administration in a slightly soluble form: isobutylidene diurea (IBDU)

Isobutylidene diurea (IBDU) was tested against urea with regard to the ammonia release in the rumen, the amount and composition of the nitrogen fraction reaching the intestine, the nitrogen and energy balances and the performance of lactating cows. Maize silage was the basal feed in all experiments. The ammonia concentration in the rumen liquor was measured in two dry cows fitted with a permanent rumen cannula. The ammonia release was clearly restrained when IBDU was substituted for urea, and the peak values were of the same order as those found with soybean meal. Two dry cows fitted with a re-entrant cannula at 10 cm from the pylorus were fed with maize silage supplemented with increasing amounts of either urea or IBDU. The duodenal flow levelled off with urea, but it continued to rise with IBDU even when high amounts were added to the silage. However, a large fraction of this increase was in the form of ammonia, corresponding to 60% of the dietary nitrogen supplied by IBDU. The amount of non-ammonia nitrogen was also higher with IBDU. The nitrogen balance of lactating cows was not noticeably affected when IBDU instead of urea was added to the maize silage. In the same manner, the digestibility of the rations and their metabolizable energy supply were not significantly modified, and the milk productions were quite similar with the two N compounds, apart from the tendency to lower milk fat and milk protein productions.     

干玉米秸秆与干羊草营养价值的比较研究

对不同保存方式的干玉米秸秆及干羊草的营养价值进行比较,结果表明:干玉米秸秆的粗蛋白含量低于干羊草(除立枯羊草外);干玉米秸秆中性洗涤纤维低于干羊草;干玉米秸秆上2/3部分酸性洗涤纤维高于干羊草;干玉米秸秆的消化率和代谢能均高于干羊草。综合分析表明:在秸秆资源丰富,草地退化严重的东北农牧交错区,玉米秸秆作为饲料具有很高的利用价值。     

Effects of variety, cropping year, location and fertilizer application on nutritive value of durum wheat straw

This study was carried out to assess the effects of variety, year, location and level of fertilizer application on chemical composition and in sacco dry matter (DM) degradability of durum wheat straw as well as to understand the relationship between straw quality and agronomic traits of the crop and to assess the possibilities of selecting wheat varieties that combine high grain yield with desirable straw quality. Two local (Arendeto and Tikur sinde) and two improved (Boohai and Gerardo) varieties of durum wheat (Triticum turgidum Desf.) were used in the experiment. The four varieties were grown at two locations (Akaki and Ejere) in the years 2001/2002 and 2002/2003 in 5 x 5 m plots in three replications. Diammonium phosphate and urea fertilizers were applied at four levels (0/0, 32/23, 41/23 and 64/46 kg/ha of nitrogen/phosphorus). Straw quality was assessed based on chemical composition and in sacco DM degradability. Correlation of straw quality with grain and straw yield and with other agronomic characteristics of the crop was determined. The potential utility index (a measure that integrates grain and digestible straw yield) was used for ranking of the varieties. The local varieties had higher crude protein (CP) and lower neutral detergent fibre contents and higher digestibility than the improved varieties. The cropping year and location had significant effect on CP content and degradability of the straw, which could be due to climatic variation. However, the fertilizer level did not have any significant effect on straw quality except that the CP content of the straw tended to increase with increasing level of fertilizer application. Based on the potential utility index the varieties ranked, in a decreasing order, as Tikur sinde > Arendeto > Gerardo > Boohai and the ranking was consistent across years and locations. Except the CP content, straw quality was not negatively correlated with grain and straw yield. This indicates that there is a possibility of selecting varieties of wheat that combine high grain and straw yield with desirable straw quality.     

Effect of feeding non-fibrous carbohydrate before grazing on intake and nitrogen utilization in dairy cows throughout the grazing season

Ten lactating cows were used to determine the effect of feeding non-fibrous carbohydrate (NFC) supplement before grazing on feed intake and nitrogen (N) utilization throughout a grazing season. The experiment was conducted from June to September. Cows grazed twice a day (2.5 h × 2) under a set stocking system and were fed NFC supplement (1 kg/4 kg of milk yield) 2 h before grazing (PRE) or immediately after grazing (POST). Cows were also fed a grass and corn silage mixture ad libitum. Herbage dry matter intake (DMI) was greater for PRE than for POST throughout the experiment and decreased from June to September. Conversely, silage DMI was less for PRE than for POST throughout the experiment and increased over the grazing season. Consequently, total DMI for PRE did not differ from that for POST. Milk urea-N concentration and urinary urea-N excretion in June did not differ between the treatments, whereas that after July was higher for PRE than for POST. Proportion of urinary N excretion to absorbed N intake in June was lower for PRE than for POST, but that after July was higher for PRE than for POST. Feeding NFC supplement before grazing would improve N utilization when cows eat large amounts of herbage high in N.