Nutrient Digestibility In Dairy Cows Research Articles

Capsaicin as a Dietary Additive for Dairy Cows: A Meta-Analysis on Performance, Milk Composition, Digestibility, Rumen Fermentation, and Serum Metabolites.

This study aimed to evaluate the effects of dietary supplementation with capsaicin (CAP) on productive performance, milk composition, nutrient digestibility, ruminal fermentation, and serum metabolites of dairy cows using a meta-analytical approach. The database included 13 studies, from which the response variables of interest were obtained. Data were analyzed using a random effects model, and results were expressed as weighted mean differences between treatments supplemented with and without CAP. Dietary supplementation with CAP increased (p < 0.05) dry matter intake, milk yield, feed efficiency, milk fat yield, and milk fat content. However, CAP supplementation did not affect (p > 0.05) milk protein and lactose yield, milk urea nitrogen, or milk somatic cell count. Greater (p < 0.05) apparent digestibility of dry matter and crude protein was observed in response to the dietary inclusion of CAP. Likewise, supplementation with CAP increased (p < 0.05) the rumen concentration of total volatile fatty acids. In contrast, CAP supplementation did not affect (p > 0.05) ruminal pH or the ruminal concentration of ammonia nitrogen, acetate, propionate, and butyrate. In blood serum, CAP supplementation increased (p < 0.05) the glucose concentration and decreased (p < 0.05) the concentration of non-esterified fatty acids. However, CAP supplementation did not affect (p > 0.05) the serum concentration of urea and beta-hydroxybutyrate. In conclusion, capsaicin can be used as a dietary additive to improve the productive performance, milk composition, and nutrient digestibility in dairy cows and, at the same time, improve the ruminal concentration of total volatile fatty acids and serum levels of glucose and non-esterified fatty acids.

PSVIII-A-6 Effects of Feeding Ground Whole Flaxseed, Defatted Flaxseed Meal and Organic Flaxseed Meal on Production Performance, Rumen Fermentation, and Total-Tract Nutrient Digestibility in Dairy Cows

Abstract This study aimed to determine the effects of feeding ground whole flaxseed and two types of mechanically extracted flaxseed meals on dry matter intake (DMI), milk production and composition, ruminal fermentation characteristics, and total-tract nutrient digestibility in dairy cows. Twelve multiparous Holstein cows [122 ± 20 days in milk (DIM) at the start of the study] were used in a replicated 4 × 4 Latin square design with 4 dietary treatments. One square had 4 ruminally cannulated cows that were used to determine dietary effects on ruminal fermentation characteristics and total tract nutrient digestibility. The 4 dietary treatments tested were a barley silage-based diet with canola meal (CM; 21.1% of diet DM) as the main protein source (designated CON), and diets containing ground whole flaxseed (designated GWF; 4.92% of diet DM), defatted flaxseed meal (designated DFM; 19.7% of diet DM), or organic flaxseed meal (designated OFM; 20.2% of diet DM) as partial replacements for CM. The crude fat contents of CM, GWF, DFM, and OFM were 3.20, 37.7, 9.9, and 12.9% (DM basis), respectively, and experimental diets were balanced for crude fat content (4.51%; DM basis). Experimental periods consisted of 18 d of dietary adaptation and 10 d of data and sample collection. Orthogonal contrasts were used to test for the following treatment differences: CON vs. GWF; CON vs. [DFM + OFM]; and GWF vs. [DFM + OFM]. Dry matter intake was lower (P &amp;lt; 0.01) for cows fed CON compared with those fed GWF and [DFM + OFM]. Milk yield tended to be greater (P = 0.06) for cows fed CON compared with those fed GWF (P = 0.06) and [DFM + OFM] (P = 0.06). Milk fat content and yield were unaffected by diet; however, milk protein content was reduced for cows fed CON compared with those fed GWF (P = 0.001) and [DFM + OFM] (P &amp;lt; 0.001). Milk urea-N (MUN) concentration was greater (P ≤ 0.001) in cows fed CON compared with those GWF and [DFM + OFM]. Also, MUN concentration was decreased for cows fed GWF compared with those fed [DFM + OFM]. Ruminal NH3-N concentration was less (P ≤ 0.04) in cows fed CON than those fed GWF and [DFM + OFM], but ruminal pH and short-chain fatty acid concentrations were unaffected by diet. Fecal N excretion (g/d) was greater (P &amp;lt; 0.01) for cows fed CON compared with those fed GWF and [DFM + OFM] and, therefore, total-tract CP digestibility was reduced (P &amp;lt; 0.001) in cows fed CON compared with those fed GWF and [DFM + OFM]. In conclusion, partial replacement of CM with GWF or [DFM + OFM] increased DMI; however, it tended to reduce milk yield.

Effects of particle size reduction of meadow hay on feed intake, performance, and apparent total tract nutrient digestibility in dairy cows

ABSTRACT Forage-based diets are encouraged in organic dairy cattle production as this can increase the net human food supply, but their voluminous nature can limit dry matter intake (DMI) and performance. This study investigates the effects of a substantial particle size reduction of hay on dairy cows’ feed intake, performance, and body characteristics, as well as on apparent total tract digestibility (ATTD). Eighteen lactating Holstein cows were allocated to two balanced feeding groups. The control group received long stem hay with a conventional particle size (CON), the experimental group received chopped hay (RED). Both groups were supplemented with concentrates (3.6 kg/d, DM basis). After 14 adaptation days, data were collected for 20 consecutive days. A covariate period of 21 days preceded the experimental feeding period. Particles retained on the 19-, 8- and 4-mm screens and on the pan of the Penn State Particle Separator accounted for 21%, 20%, 20% and 39% of the RED hay. CON hay consisted of 72% large particles, followed by 8%, 7% and 13% retained on the other screens. Average DMI levels of cows in the CON group reached 20.8 kg/d, with a nonsignificant increase (+1.05 kg/d) in the RED group (p = 0.28). Intakes of both NFC (+0.65 kg/d, p = 0.01) and CP (+0.28 kg/d, p = 0.05) were significantly greater in the RED group, resulting in a slightly increased milk yield (+0.8 kg energy corrected milk/d) (p = 0.45), likely because the ATTD decreased significantly when feeding RED hay. No impact was observed on energy balance (103.7 vs 103.9%, p = 0.95), feed conversion efficiency (kg ECM/kg DMI), or N use efficiency. Overall, the results indicate increases in intake of NFC and CP in the RED group when feeding a hay-based (>83%, DM basis) diet, but also a decrease in nutrient digestibility, likely due to increased passage rate, potentially because of the high fraction of hay particles < 4 mm. In conclusion, hay-based rations with a lower proportion of fine particles should be tested to exploit the potential of particle size reduction in terms of improving hay use efficiency.

Lactational performance, feeding behavior, ruminal fermentation and nutrient digestibility in dairy cows fed whole-plant faba bean silage-based diet with fibrolytic enzyme

Whole-plant faba bean silage has a high content in indigestible fiber. Improvement of fiber digestibility of faba bean silage would benefit animal production. However, there is no study on pretreating fibrolytic enzyme in whole-plant faba bean silage-based diet for dairy cows on animal performance. The objectives of this study were to evaluate the effects of pretreating whole-plant faba bean silage-baseddiet with fibrolytic enzyme (a mixture of xylanase and cellulase; AB Vista, UK) derived from Trichoderma reesei(FETR) on lactational performance, digestibility, ruminal fermentation characteristics, and feeding behavior of dairy cows. The animal trial was conducted using eight lactating Holstein cows (BW = 710 ± 44 kg and Days in Milk (DIM) = 121 ± 17 days) with four levels of FETR (0, 0.5, 0.75, and 1.0 mL of FETR/kg DM of silage) in a replicated Latin square design. These enzyme treatments were selected based on the previous in situ and in vitro findings that showed positive responses to the whole-plant faba bean silage. The enzyme treatments were directly applied on the silage prior to mixing process. The total mixed rations contained 31% of faba bean silage, 14% of grass hay, 3.5% of straw, 30% of barley and corn grain and 21.5% of concentrate. There was no significant difference of applying FETR on nutrient intake (P > 0.05) except for CP intake, which was reduced in FETR group compared to control (P < 0.01, 4.4 vs 4.54 kg/d). There was a linear effect found in NDF digestibility when treated with FETR, where maximum improvement was achieved with 0.5 mL of FETR application. The milk fat yield, percentage of milk fat and fat-corrected milk were linearly affected by the increasing level of enzyme. The cows fed a diet supplemented with enzymes tended to have a lower milk fat. Feed efficiency linearly responded to incremental levels of FETR. There was no enzyme effect on feeding behavior and nitrogen balance and utilization. Results from this study indicated that supplementing fibrolytic enzyme on whole-plant faba bean silage diets for dairy cows improved lactational performance, intake and digestibility with 0.5 mL of FETR application. However, adding higher enzyme level resulted in negative effects on animal performance.

Effects of Capsicum Oleoresin Supplementation on Lactation Performance, Plasma Metabolites, and Nutrient Digestibility of Heat Stressed Dairy Cow.

Simple SummaryHeat stress has significant adverse effects on the lactation performance of dairy cows. Therefore, novel feed additives that alleviate heat stress are continuously being researched and developed to deal with this predicament. On this basis, the effects of Capsicum oleoresin supplementation on the lactation performance, rectal temperature, plasma metabolites, and nutrient digestibility of dairy cows were studied. The results showed that the dietary addition of Capsicum oleoresin could improve dry matter intake, milk yield, and milk quality, and reduce the rectal temperature of dairy cows. Furthermore, Capsicum oleoresin supplementation also alters plasma metabolites. In summary, Capsicum oleoresin could effectively be used as a feed additive to relieve heat stress in dairy cows.The present study investigates the effect of Capsicum oleoresin (CAP) supplementation on the dry matter intake, milk performance, plasma metabolites, and nutrient digestibility of dairy cows during the summer. Thirty-two lactating Holstein dairy cows (n = 32) were randomly divided into four groups. The CAP was dissolved in water and added to the total mixed ration with graded levels of CAP (0, 20, 40, and 80 mg/kg of dry matter). The trial period consisted of seven days for adaptation and thirty days for sampling. Data were analyzed using the MIXED and GLM procedure SAS. The linear and quadratic effects were tested. The milk yield, milk fat, and milk urea nitrogen increased linearly with the dietary addition of CAP (p < 0.05). The dry matter intake increased linearly in the 20CAP group (p < 0.05). Additionally, the 4% fat-corrected milk, energy-corrected milk, milk fat yield, and milk fat to milk protein ratio increased quadratically (p < 0.05), while the rectal temperature decreased quadratically (p < 0.05). Serum total cholesterol and non-esterified fatty acids increased linearly (p < 0.05); glucose and β-hydroxybutyrate tended to increase quadratically with the dietary addition of CAP (p = 0.05). Meanwhile, CAP supplementation did not affect the milk protein yield, blood concentration of triglyceride, insulin, lipopolysaccharide, immunoglobulin G, or heat shock protein 70 expression level (p > 0.05). In addition, nutrient digestibility was comparable among groups (p > 0.05). These findings indicated that CAP supplementation could enhance the lactation performance of dairy cows during the summer.

Nutrient digestibility of dairy cows fed with chopped and ensiled elephant grass

Forage scarcity hinders the development of the dairy farm. Developing measures for preserving and optimizing forage supply are among the solutions to cope with this problem. This research aimed to evaluate nutrient digestibility of dairy cows given different forage treatments. The forage used was elephant grass (EG, Pennisetum purpureum) and subjected to four dietary treatments, i.e., intact EG (FW), chopped EG (FC), ensiled EG (SW), and ensiled and chopped EG (SC). Proximate analyses were performed on the respective treatments. The in vivo evaluation was then conducted by feeding the diets to dairy cows with a 4 × 4 Latin square design set (n=4 replications). Each period’s length was 21 days, in which the first 14 days was for feed adaptation, and the last seven days was for collecting data. Results showed that chopping and ensiling treatments improved daily feed consumption. Ensiled EG (SW and SC) resulted significantly (p<0.05) higher in dry matter, organic matter, and crude fat digestibility compared to non ensiled EG (FC and FW). Crude protein digestibility for SC treatment was significantly higher (p<0.05) among all treatments. Crude fiber digestibility for SC treatment was also significantly (P<0.05) higher among all treatments with an exemption of SW. The effectiveness of treatments on feed consumption and nutrient digestibility can be sorted, as follows SC>SW>FW>FC. It can be concluded that combination of chopping and ensiling (SC) proved the best result and thus may be implemented to preserve and optimize forage supply.

Effects of copper sulphate and coated copper sulphate addition on lactation performance, nutrient digestibility, ruminal fermentation and blood metabolites in dairy cows.

Coated copper sulphate (CCS) could be used as a Cu supplement in cows. To investigate the influences of copper sulphate (CS) and CCS on milk performance, nutrient digestion and rumen fermentation, fifty Holstein dairy cows were arranged in a randomised block design to five groups: control, CS addition (7·5 mg Cu/kg DM from CS) or CCS addition (5, 7·5 and 10 mg Cu/kg DM from CCS, respectively). When comparing Cu source at equal inclusion rates (7·5 mg/kg DM), cows receiving CCS addition had higher yields of fat-corrected milk, milk fat and protein; digestibility of DM, organic matter (OM) and neutral-detergent fibre (NDF); ruminal total volatile fatty acid (VFA) concentration; activities of carboxymethyl cellulase, cellobiase, pectinase and α-amylase; populations of Ruminococcus albus, Ruminococcus flavefaciens and Fibrobacter succinogenes; and liver Cu content than cows receiving CS addition. Increasing CCS addition, DM intake was unchanged, yields of milk, milk fat and protein; feed efficiency; digestibility of DM, OM, NDF and acid-detergent fibre; ruminal total VFA concentration; acetate:propionate ratio; activity of cellulolytic enzyme; populations of total bacteria, protozoa and dominant cellulolytic bacteria; and concentrations of Cu in serum and liver increased linearly, but ruminal propionate percentage, ammonia-N concentration, α-amylase activity and populations of Prevotella ruminicola and Ruminobacter amylophilus decreased linearly. The results indicated that supplement of CS could be substituted with CCS and addition of CCS improved milk performance and nutrient digestion in dairy cows.

KECERNAAN ENERGI DAN KECERNAAN NUTRIEN TOTAL PADA TERNAK SAPI PERAH YANG DIBERIKAN PAKAN LENGKAP BERBASIS TEBON JAGUNG

ENERGY DIGESTIBILITY AND TOTAL DIGESTIBLE NUTRIENT IN DAIRY COWS GIVEN COMPLETE FEED BASED ON CORN FORAGE. The purpose of this research was to examine the value of energy digestibility and total nutrient digestibility in dairy cows which are given complete feed based on corn forage. 14 head of cattle with age ± 6-8 years weighing 300-400 kg were used in this study. This biological experiment used a statistical analysis of the T test with unequal variations (t-test two sample assuming unequel variance). The treatments consists of: Ra (30% Concentrate + 70% Corn forage), and Rb (30% Concentrate + 35% Corn forage + 35% King Grass). The results showed that the energy intake both of treatments(Ra and Rb) were not significantly different (P &lt;0.05) while the energy digestibility and total digestible nutrient of the Rb treatment were significantly higher (P &lt;0.05) than Ra treatment. It can be concluded that feed treatment using of 30% oncentrate, 35% king grass, and 35% corn forage was obtained the best energy disgestibility and total digestible nutrient values.Keywords: energy digestibility, dairy cows. corn forage , king grass.

Diet with Concentrate Containing Durio zibethinus Murr Seed Meal: Nutrient Contents, Fatty Acid Profiles, In Vitro Characteristics, and Nutrient Digestibility in Dairy Cows

This research was to evaluate concentrate diet containing Durio zibethinus seed meal (DSM) on nutrient contents, fatty acid profiles, in vitro characteristics, and nutrients digestibility in dairy cows. The experiment was arranged in Latin Square 4 x 4 design with 4 lactating dairy cows in 4 periods in 2 weeks for each period. The treatments were diets with concentrate containing ratios of rice bran and DSM, DC 35/12.5 (35% of Rice bran+ 12.5% of DSM), DC 27.5/20 (27.5% of Rice bran+ 20% of DSM), DC 20/27.5 (20% of Rice bran+ 27.5% of DSM) and DC 12.5/35 (12.5% of Rice bran+ 35% of DSM). Data were analyzed using analysis of variance (Anova), if any significant difference among treatment means were found, will be further analyzed using Duncan Multiple Range Test (DMRT). Results showed that 20% of DSM supplemented in concentrate improved nutrient contents of crude protein, ether extract, medium chain fatty acid (MCFA), long chain fatty acid (LCFA), polyunsaturated fatty acid (PUFA), unsaturated fatty acid (UFA), and n6/n3. In vitro dry matter digestibility, organic matter digestibility, N-NH3, and total VFA were high in concentrate containing 35% DSM. However, in vivo digestibility evaluation showed nutrient intakes were no differences among treatments. Nutrient digestibility were found higher in diet with concentrate containing 27.5% of DSM. There were three different optimal levels could be suggested, 20% of DSM (for nutrient and fatty acid content), 27.5% of DSM (for nutrient digestibility), and 35% of DSM (for in vitro characteristics). Supported by previous milk production, it was concluded that the 27.5% of DSM was suggested to be applied in concentrate for dairy cows.

Effects of Dietary Alkyl Polyglycoside Supplementation on Lactation Performance, Blood Parameters and Nutrient Digestibility in Dairy Cows

Simple SummaryThis project investigated the effects of alkyl polyglycoside (APG), a non-ionic surfactant, on lactation performance, blood metabolites and nutrient digestibility of lactating dairy cows, and found that the addition of APG at doses up to 22 mL/kg of pelleted concentrate (around 9 mL/kg of diet or 100 mL/day/head) had positive effects on milk quality in dairy cows.This study evaluated the effects of alkyl polyglycoside (APG), which is a non-ionic surfactant, on lactation performance, nutrient digestibility and blood metabolites in dairy cows. Twenty dairy cows were randomly divided into four groups and fed a basal diet that included pelleted concentrate, distillers grains, and fresh limpograss. The four treatments included 0, 5.5, 11 and 22 mL APG per kg of pelleted concentrate on a dry matter basis; treatments were defined as APG0, APG5.5, APG11, and APG22, respectively. Dry matter intake was not affected by APG supplementation. There was an increase in milk yield (from 13.96 to 16.71 kg/day) and increases in milk fat (quadratic, p = 0.04), protein (quadratic, p = 0.10), and lactose concentrations (linear, p = 0.07) with increasing APG supplementation. In addition, APG supplementation increased (p ≤ 0.03) the milk fat, protein, solid non-fat, and total solid yields, while the lactose yield increased (linear, p = 0.01) as the APG level increased. Dietary APG supplementation had no effect on nutrient digestibility and blood metabolites. It was concluded that the addition of APG at doses up to 22 mL/kg of pelleted concentrate had positive effects on the milk composition in dairy cows.

Effects of intraruminal urea-nitrogen infusions on feed intake, nitrogen utilization, and milk yield in dairy cows

The objective of this study was to determine the effects of supplementation of protein deficient diet with increasing amounts of urea-N on feed intake, milk yield, rumen fermentation, and nutrient digestibility in dairy cows. The hypothesis was that low rumen ammonia-N concentrations provide suboptimal conditions for rumen microbes and these conditions can be alleviated by urea-N that increases rumen ammonia-N concentrations. To evaluate this hypothesis, the diet was formulated slightly deficient with respect to rumen-degradable protein. To supplement the diet with rumen degradable N, 5 levels of urea-N (0, 17, 33, 49, and 66 g/d) were continuously infused into the rumen of 5 dairy cows according to a 5 × 5 Latin square. Increasing levels of urea-N infusion increased N intake and N excretion in urine and feces in a linear manner and tended to increase milk and milk protein yields. Feed intake and fiber digestibility were not affected by urea-N infusion levels. Rumen ammonia-N concentrations remained low (3.5 mg/100 mL) and did not respond to urea-N infusions levels between 0 to 49 g/d, whereas the highest level of urea-N (66 g/d) increased rumen ammonia-N concentration to 5.1 mg/100 mL (quadratic effect). These observations suggested that rumen microbes efficiently captured ammonia-N from rumen fluid until sufficient intracellular ammonia-N concentrations were attained, after which ammonia-N concentrations started to increase in extracellular rumen fluid. In contrast, milk urea-N concentrations increased in a curvilinear manner (cubic effect) from 4.4 to around 6 mg/100 mL for the medium levels of urea-N and then to 7.9 mg/100 mL for the highest level of urea-N infusion. The current results indicated that 18% of supplementary N intake was secreted in milk and 53% in urine. In spite of low rumen ammonia-N concentrations observed for the basal diet, it was estimated that only 43% of supplementary N was captured by rumen microbes. Estimated true digestibility for supplementary N (93%) provided further evidence that urea-N stimulated microbial N synthesis. The current results indicate that rumen ammonia-N concentration was an insensitive indicator of N deficiency at low levels of diet CP, whereas milk urea-N was responsive to diet CP concentrations at all urea-N infusion levels.

Short communication: Effects of prill size of a palmitic acid–enriched fat supplement on the yield of milk and milk components, and nutrient digestibility of dairy cows

The objective of our experiment was to evaluate the effects of prill size of a palmitic acid–enriched fatty acid supplement (PA; 85% C16:0) on feed intake, nutrient digestibility, and production responses of dairy cows. Twenty-four primiparous and multiparous Holstein cows were assigned based on parity and production level to replicated 4×4 Latin squares balanced for carryover effects with 21-d periods. Treatments were a control diet (no added PA), or 2.0% PA added as a small prill size (PA-SM; 284±12.4µm), a medium prill size (PA-MD; 325±14.7µm), or a large prill size (PA-LG; 600±17.4µm) supplement. Overall, PA treatments increased milk fat content (4.25 vs. 3.99%), milk fat yield (1.48 vs. 1.39kg/d), 3.5% fat-corrected milk (39.2 vs. 37.7kg/d), and improved feed efficiency (fat-corrected milk:dry matter intake; 1.51 vs. 1.42) compared with control. Compared with control, PA treatments did not affect dry matter intake, body weight, body condition score, or yields of milk, protein, and lactose. The PA treatments increased neutral detergent fiber digestibility (44.8 vs. 42.4%) and reduced the digestibility of 16-carbon fatty acids (72.3 vs. 79.1%) and total fatty acids (76.6 vs. 80.3%). Compared with control, PA treatments reduced the contents of de novo synthesized milk fatty acids (23.0 vs. 25.8g/100g of fatty acids) and preformed milk fatty acids (36.3 vs. 39.1g/100g of fatty acids), but did not affect their yields. In contrast, PA treatments increased the content (40.8 vs. 35.1g/100g of fatty acids) and yield (570 vs. 436g/d) of 16-carbon milk fatty acids compared with control. The PA prill size had no effect on dry matter intake, yield of milk and milk components, or feed efficiency. However, PA-LG tended to increase milk fat content compared with PA-SM (4.28 vs. 4.22%), and it increased 16-carbon fatty acid digestibility compared with PA-MD (74.2 vs. 71.0%) and PA-SM (74.2 vs. 71.7%). Additionally, PA-LG increased total fatty acid digestibility compared with PA-MD (78.1 vs. 75.6%) and PA-SM (78.1 vs. 76.0%). Results demonstrate that PA increased milk fat content and yield, and feed efficiency. Reducing prill size decreased fatty acid digestibility, but it had no effect on animal performance under the dietary conditions and prill sizes evaluated.

Effects of ruminally degradable starch levels on performance, nitrogen balance, and nutrient digestibility in dairy cows fed low corn-based starch diets

ObjectiveThis trial was performed to examine the effects of ruminally degradable starch (RDS) levels in total mixed ration (TMR) with low corn-based starch on the milk production, whole-tract nutrient digestibility and nitrogen balance in dairy cows.MethodsEight multiparous Holstein cows (body weight [BW]: 717±63 kg; days in milk [DIM]: 169±29) were assigned to a crossover design with two dietary treatments: a diet containing 62.3% ruminally degradable starch (% of total starch, low RDS) or 72.1% ruminally degradable starch (% of total starch, high RDS). Changes to the ruminally degradable levels were conducted by using either finely ground corn or steam-flaked corn as the starch component.ResultsThe results showed that dry matter intake, milk yield and composition in dairy cows were not affected by dietary treatments. The concentration of milk urea nitrogen was lower for cows fed high RDS TMR than low RDS TMR. The whole-tract apparent digestibility of neutral detergent fiber, acid detergent fiber and crude protein decreased, and that of starch increased for cows fed high RDS TMR over those fed low RDS TMR, with no dietary effect on the whole-tract apparent digestibility of dry matter and organic matter. The proportion of urinary N excretion in N intake was lower and that of fecal N excretion in N intake was higher for cows fed high RDS TMR than those fed low RDS TMR. The N secretion in milk and the retention of N were not influenced by the dietary treatments. Total purine derivative was similar in cows fed high RDS TMR and low RDS TMR. Consequently, estimated microbial N flow to the duodenum was similar in cows fed high RDS TMR and low RDS TMR.ConclusionResults of this study show that ruminally degradable starch levels can influence whole-tract nutrient digestibility and nitrogen balance in dairy cows fed low corn-based starch diets, with no influence on performance.

Effect of dietary nitrate level on enteric methane production, hydrogen emission, rumen fermentation, and nutrient digestibility in dairy cows

Nitrate may lower methane production in ruminants by competing with methanogenesis for available hydrogen in the rumen. This study evaluated the effect of 4 levels of dietary nitrate addition on enteric methane production, hydrogen emission, feed intake, rumen fermentation, nutrient digestibility, microbial protein synthesis, and blood methemoglobin. In a 4×4 Latin square design 4 lactating Danish Holstein dairy cows fitted with rumen, duodenal, and ileal cannulas were assigned to 4 calcium ammonium nitrate addition levels: control, low, medium, and high [0, 5.3, 13.6, and 21.1g of nitrate/kg of dry matter (DM), respectively]. Diets were made isonitrogenous by replacing urea. Cows were fed ad libitum and, after a 6-d period of gradual introduction of nitrate, adapted to the corn-silage-based total mixed ration (forage:concentrate ratio 50:50 on DM basis) for 16d before sampling. Digesta content from duodenum, ileum, and feces, and rumen liquid were collected, after which methane production and hydrogen emissions were measured in respiration chambers. Methane production [L/kg of dry matter intake (DMI)] linearly decreased with increasing nitrate concentrations compared with the control, corresponding to a reduction of 6, 13, and 23% for the low, medium, and high diets, respectively. Methane production was lowered with apparent efficiencies (measured methane reduction relative to potential methane reduction) of 82.3, 71.9, and 79.4% for the low, medium, and high diets, respectively. Addition of nitrate increased hydrogen emissions (L/kg of DMI) quadratically by a factor of 2.5, 3.4, and 3.0 (as L/kg of DMI) for the low, medium, and high diets, respectively, compared with the control. Blood methemoglobin levels and nitrate concentrations in milk and urine increased with increasing nitrate intake, but did not constitute a threat for animal health and human food safety. Microbial crude protein synthesis and efficiency were unaffected. Total volatile fatty acid concentration and molar proportions of acetate, butyrate, and propionate were unaffected, whereas molar proportions of formate increased. Milk yield, milk composition, DMI and digestibility of DM, organic matter, crude protein, and neutral detergent fiber in rumen, small intestine, hindgut, and total tract were unaffected by addition of nitrate. In conclusion, nitrate lowered methane production linearly with minor effects on rumen fermentation and no effects on nutrient digestibility.

Ruminal disappearance of phosphorus and starch, reticuloruminal pH and total tract nutrient digestibility in dairy cows fed diets differing in grain processing

Ruminal disappearance kinetics of nutrients such as phosphorus (P), starch and protein in cereal grains is determinant of their nutritional and health value in ruminants. The objective of the present in vivo and in situ trials was to evaluate whether feeding barley grain processed with lactic acid (LA), with or without thermal treatment, affects in situ degradation kinetics of nutrients, reticuloruminal pH dynamics, and apparent total tract digestibility (ATTD) in dairy cows. The experiment involved 6 rumen-fistulated Holstein cows in a double 3×3 Latin square design fed a diet based on differently processed barley grain: untreated grain as control (CON), or grain treated with 1% LA alone (LA diet), or 1% LA plus oven-heating (LAH diet) prior to feeding. Each experimental period lasted 21 d, with the first 11 d used for adaptation to the diets. The in situ trial consisted in the incubation of the differently treated barley grains (i.e., CON, LA, LAH) up to 48h in the rumen of cows fed diets containing the respective barleys. The reticuloruminal pH and temperature were continuously measured throughout the experiment via wireless indwelling sensors. In situ data demonstrated increased (P<0.001) disappearance of barley P, being on average more than twice as high during the first 24h of incubation with LA and LAH compared to CON barley. In contrast, the degradation of starch decreased (P<0.05) after 2h and 4h of the ruminal incubation, but not thereafter. Feed intake remained unchanged among treatment groups, whereas ATTD of dry matter was slightly greater (P=0.05) in cows fed the LA-treated barley. There was no effect of diet on reticuloruminal pH and temperature dynamics either. In conclusion, the present study indicates that treatment of barley grain with LA and LAH lowers rumen degradability of starch early after incubation, without affecting reticuloruminal pH and the ATTD of most nutrients. The improved ruminal disappearance of barley P suggests an improved solubility and faster ruminal availability of organic P of the treated grain, and warrants further investigations to tap its potential with regards to improved P nutrition and minimization of P excretion in dairy cows.

Brown midrib corn shredlage in diets for high-producing dairy cows

A novel method of harvesting whole-plant corn silage, shredlage, may increase kernel processing and physically effective fiber. Improved fiber effectiveness may be especially advantageous when feeding brown midrib (BMR) corn hybrids, which have reduced lignin content. The objective of this study was to determine the effect of feeding TMR containing BMR corn shredlage (SHRD) compared with BMR conventionally processed corn silage (KP) or KP plus chopped alfalfa hay (KPH) on intake, lactation performance, and total-tract nutrient digestibility in dairy cows. The KP was harvested using conventional rolls (2-mm gap) and the self-propelled forage harvester set at 19mm of theoretical length of cut, whereas SHRD was harvested using novel cross-grooved rolls (2-mm gap) and the self-propelled forage harvester set at 26mm of theoretical length of cut. Holstein cows (n=120; 81±8 d in milk at trial initiation), stratified by parity, days in milk, and milk yield, were randomly assigned to 15 pens of 8 cows each. Pens were randomly assigned to 1 of 3 treatment diets, SHRD, KP, or KPH, in a completely randomized design using a 2-wk covariate period with cows fed a common diet followed by a 14-wk treatment period with cows fed their assigned treatment diet. The TMR contained (dry matter basis) KP or SHRD forages (45%), alfalfa silage (10%), and a concentrate mixture (45%). Hay replaced 10% of KP silage in the KPH treatment TMR (dry matter basis). Milk, protein, and lactose yields were 3.4, 0.08, and 0.16kg/d greater, respectively, for cows fed KP and SHRD than KPH. A week by treatment interaction was detected for milk yield, such that cows fed SHRD produced or tended to produce 1.5kg/d per cow more milk, on average, than cows fed KP during 6 of the 14 treatment weeks. Component-corrected milk yields were similar among treatments. Cows fed KPH had greater milk fat concentration than cows fed KP and SHRD (3.67 vs. 3.30% on average). Consumption of dry matter, rumination activity, and sorting behavior were similar among treatments. Ruminal in situ starch digestibility was greater for SHRD than KP forages, and total-tract dietary starch digestibility was greater for SHRD than KP. Milk yield and starch digestibility were greater for SHRD than KP. Lack of improvement in milk fat content and rumination activity for SHRD compared with KP and reduced milk fat content for SHRD compared with KPH, however, suggest no improvement in physically effective fiber from the longer theoretical length of cut used with SHRD in a BMR hybrid.

Incremental amounts of ground flaxseed decrease milk yield but increase n-3 fatty acids and conjugated linoleic acids in dairy cows fed high-forage diets1

The objective of this study was to investigate the effect of incremental amounts of ground flaxseed (GFX) on milk yield and concentrations and yields of milk components, milk fatty acids (FA) profile, ruminal metabolism, and nutrient digestibility in dairy cows fed high-forage diets. Twelve multiparous Jersey cows averaging (mean ± SD) 112±68d in milk and 441±21kg of body weight and 8 primiparous Jersey cows averaging 98±43d in milk and 401±43kg of body weight were randomly assigned to treatment sequences in a replicated 4×4 Latin square design. Each period lasted 21d with 14d for diet adaptation and 7d for data and sample collection. Treatments were fed as a total mixed ration (63:37 forage-to-concentrate ratio) with corn meal and soybean meal replaced by incremental levels (i.e., 0, 5, 10, or 15% diet dry matter) of GFX. The ruminal molar proportions of acetate and butyrate decreased linearly with GFX supplementation, whereas the ruminal molar proportion of propionate increased linearly resulting in decreased acetate-to-propionate ratio. Apparent total-tract digestibilities of nutrients either decreased (dry matter) or tended to decrease (organic matter, neutral detergent fiber, acid detergent fiber) linearly in cows fed GFX. Milk yield decreased linearly in cows fed increasing amounts of GFX, which is explained by the linear reduction in dry matter intake. Except for the concentrations of milk protein and urea N, which decreased linearly with GFX supplementation, no other changes in the concentration of milk components were observed. However, yields of milk protein and fat decreased linearly with GFX supplementation. The linear decrease in the yields of milk fat and protein are explained by reduced milk yield, whereas that in milk urea N is explained by decreased crude protein intake. No treatment effects were observed for plasma urea N and nonesterified fatty acids, serum cortisol, and body weight change. Milk odd- and branched-chain FA and saturated FA decreased linearly with GFX supplementation. Milk trans-11 18:1, α-linolenic acid, cis-9,trans-11 18:2, and the sum of n-3 FA all increased linearly and quadratically, whereas the milk ratio of n-6 to n-3 decreased linearly in cows fed GFX. Overall, compared with the control diet (0% GFX), the diet with 15% GFX supplementation resulted in the lowest milk yield but highest milk proportions and yields (data not shown) of cis-9,trans-11 18:2 and n-3 FA.

Saturated fat supplementation interacts with dietary forage neutral detergent fiber content during the immediate postpartum and carryover periods in Holstein cows: Production responses and digestibility of nutrients

Forty-eight multiparous cows were used in a randomized complete block design experiment with a 2×2 factorial arrangement of treatments to determine the interaction between a highly saturated free FA supplement (SFFA) and dietary forage neutral detergent fiber (fNDF) content on production responses and nutrient digestibility of dairy cows in the postpartum period. Treatment diets were offered from 1 to 29d postpartum (postpartum period; PP) and contained 20 or 26% fNDF (50:50 corn silage:alfalfa silage and hay, dry matter basis) and 0 or 2% SFFA [Energy Booster 100 (Milk Specialties Global, Eden Prairie, MN); 96.1% FA: 46.2% C18:0 and 37.0% C16:0]. From 30 to 71d postpartum (carryover period), a common diet (~23% fNDF, 0% SFFA) was offered to all cows to evaluate carryover effects of the treatment diets early in lactation. During the PP, higher fNDF decreased dry matter intake (DMI) by 2.0 kg/d, whereas SFFA supplementation increased it by 1.4kg/d. In addition, high fNDF with 0% SFFA decreased DMI compared with the other diets and this difference increased throughout the PP. Treatments did not affect 3.5% fat-corrected milk yield during the PP but did during the carryover period when SFFA supplementation decreased 3.5% fat-corrected milk yield for the low-fNDF diet (51.1 vs. 58.7kg/d), but not for the high-fNDF diet (58.5 vs. 58.0kg/d). During the PP, lower fNDF and SFFA supplementation decreased body condition score loss. A tendency for an interaction between fNDF and SFFA indicated that low fNDF with 2% SFFA decreased body condition score loss compared with the other diets (−0.49 vs. −0.89). During the PP, lower fNDF and 2% SFFA supplementation decreased feed efficiency (3.5% fat-corrected milk/DMI) by 0.30 and 0.23 units, respectively. The low-fNDF diet with 2% SFFA decreased feed efficiency compared with other diets early in the PP, but this difference decreased over time. Supplementation of SFFA in the PP favored energy partitioning to body reserves and limited DMI depression for the high-fNDF diet, which might allow higher-fNDF diets to be fed to cows in the PP. However, SFFA supplemented in the low-fNDF diet during the PP affected production negatively in the carryover period. Dietary fNDF and SFFA interacted, affecting performance in the PP with carryover effects when cows were fed a common diet in early lactation.

Effect of corn silage hybrids differing in starch and neutral detergent fiber digestibility on lactation performance and total-tract nutrient digestibility by dairy cows

Selection for hybrids with greater starch and NDF digestibility may be beneficial for dairy producers. The objective of this study was to determine the effect of feeding a TMR containing a floury-leafy corn silage hybrid (LFY) compared with a brown midrib corn silage hybrid (BMR) for intake, lactation performance, and total-tract nutrient digestibility in dairy cows. Ninety-six multiparous Holstein cows, 105±31d in milk at trial initiation, were stratified by DIM and randomly assigned to 12 pens of 8 cows each. Pens were randomly assigned to 1 of 2 treatments, BMR or LFY, in a completely randomized design; a 2-wk covariate period with cows fed a common diet followed by a 14-wk treatment period with cows fed their assigned treatment diet. Starch digestibilities, in situ, in vitro, and in vivo, were greater for LFY compared with BMR; the opposite was observed for NDF digestibility. Cows fed BMR consumed 1.7kg/d more dry matter than LFY. Although, actual-, energy-, and solids-corrected milk yields were greater for BMR than LFY, feed conversions (kg of milk or component-corrected milk per kg of DMI) did not differ. Fat-corrected milk and milk fat yield were similar, as milk fat content was greater for cows fed LFY (4.05%) than BMR (3.83%). Cows fed BMR had lower milk urea nitrogen concentration, but greater milk protein and lactose yields compared with LFY. Body weight change and condition score were unaffected by treatment. Total-tract starch digestibility was greater for cows fed the LFY corn silage; however, dry matter intake and milk and protein yields were greater for cows fed the BMR corn silage. Although total-tract starch digestibility was greater for cows fed the LFY corn silage, feed efficiency was not affected by hybrid type due to greater dry matter intake and milk and protein yields by cows fed the BMR corn silage.

泌乳牛における糞尿排泄量，窒素出納および養分消化率と血液成分との関連性

泌乳牛における糞尿排泄量，窒素（N）出納，養分消化率および第一胃微生物態N合成量（MNS）と血液成分との関連性を検討するため，初産牛と経産牛を４頭ずつ供試し，一期14日間のクロスオーバー法で全糞尿採取法によるN出納試験を行った．糞尿排泄量，N出納，養分消化率およびMNSに関する27項目を目的変数とし，血液成分を3つの説明変数群（飼料摂取前，飼料摂取後および飼料摂取前後の差，各13項目）として，81例の重回帰分析を行った．その結果，有用な重回帰式（決定係数（R2） ≧0.5）が62式得られた．これらのうち，飼料摂取前の血液成分を説明変数群とした場合，尿中へのN排泄量，糞尿合計へのN排泄量，乳中へのN排泄量，尿中へのN排泄割合および非繊維性炭水化物（NFC）消化率において精度の高い重回帰式（R2≧0.8）が得られた．飼料摂取後の血液成分を説明変数群とした場合，尿量，N摂取量，糞中へのN排泄量，尿中へのN排泄量，糞尿合計へのN排泄量，糞中へのN排泄割合，N消化率，粗脂肪消化率およびNFC消化率において精度の高い重回帰式が得られた．飼料摂取前後の差を説明変数群とした場合，生糞量，糞中へのN排泄量，糞尿合計へのN排泄量，中性デタージェント繊維消化率において精度の高い重回帰式が得られた． 以上のことから，血液成分が泌乳牛の糞尿排泄量，N出納および養分消化率を反映していることが証明され，野外での把握が困難であったこれらの値を血液成分から推定できることが示唆された．