Total Tract Digestibility Of Dry Matter Research Articles

Effects of rumen-protected Capsicum oleoresin on productivity and responses to a glucose tolerance test in lactating dairy cows

The objective of this experiment was to investigate the effects of rumen-protected Capsicum oleoresin (RPC) supplementation on feed intake, milk yield and composition, nutrient utilization, fecal microbial ecology, and responses to a glucose tolerance test in lactating dairy cows. Nine multiparous Holstein cows were used in a replicated 3 × 3 Latin square design balanced for residual effects with three 28-d periods. Each period consisted of 14 d for adaptation and 14 d for data collection and sampling. Treatments were 0 (control), 100, and 200 mg of RPC/cow per day. They were mixed with a small portion of the total mixed ration and top-dressed. Glucose tolerance test was conducted once during each experimental period by intravenous administration of glucose at a rate of 0.3 g/kg of body weight. Dry matter intake was not affected by RPC. Milk yield tended to increase for RPC treatments compared to the control. Feed efficiency was linearly increased by RPC supplementation. Concentrations of fat, true protein, and lactose in milk were not affected by RPC. Apparent total-tract digestibility of dry matter, organic matter, and crude protein was linearly increased, and fecal nitrogen excretion was linearly decreased by RPC supplementation. Rumen-protected Capsicum oleoresin did not affect the composition of fecal bacteria. Glucose concentration in serum was not affected by RPC supplementation post glucose challenge. However, compared to the control, RPC decreased serum insulin concentration at 5, 10, and 40 min post glucose challenge. The area under the insulin concentration curve was also decreased 25% by RPC. Concentration of nonesterified fatty acids and β-hydroxybutyrate in serum were not affected by RPC following glucose administration. In this study, RPC tended to increase milk production and increased feed efficiency in dairy cows. In addition, RPC decreased serum insulin concentration during the glucose tolerance test, but glucose concentration was not affected by treatment.

The effect of varying proportion and chop length of lucerne silage in a maize silage-based total mixed ration on diet digestibility and milk yield in dairy cattle

The objective was to assess the effects of inclusion rate and chop length of lucerne silage, when fed in a total mixed ration (TMR), on milk yield, dry matter (DM) intake (DMI) and digestion in dairy cows. Diets were formulated to contain a 50 : 50 ratio of forage : concentrate (DM basis) and to be isonitrogenous (170 g/kg CP). The forage portion of the offered diets was comprised of maize and lucerne silage in proportions (DM basis) of either 25 : 75 (high Lucerne (HL)) or 75 : 25 (low lucerne (LL)). Lucerne was harvested and conserved as silage at either a long (L) or short (S) chop length. These variables were combined in a 2×2 factorial arrangement to give four treatments (HLL, HLS, LLL, LLS) which were fed in a Latin square design study to Holstein dairy cows in two separate experiments. In total, 16 and 8 multiparous, mid-lactation cows were used in experiments 1 and 2, respectively. To ensure sufficient silage for both experiments, different cuts of lucerne silage (taken from the same sward) were used for each experiment: first cut for experiment 1 (which was of poorer quality) and second cut for experiment 2. Dry matter intake, milk yield and milk composition where measured in both experiments, and total tract digestibility and nitrogen (N) balance were assessed using four cows in experiment 2. In experiment 1, cows fed LL had increased DMI (+3.2 kg/day), compared with those fed HL. In contrast, there was no difference in DMI due to lucerne silage inclusion rate in experiment 2. A reduction in milk yield was observed with the HL treatment in both experiment 1 and 2 (−3.0 and −2.9 kg/day, respectively). The HL diet had reduced digestibility of DM and organic matter (OM) (−3% and −4%, respectively), and also reduced the efficiency of intake N conversion into milk N (−4%). The S chop length increased total tract digestibility of DM and OM (both +4%), regardless of inclusion rate. Inclusion of lucerne silage at 25% of forage DM increased milk yield relative to 75% inclusion, but a S chop length partially mitigated adverse effects of HL on DMI and milk yield in experiment 1 and on DM digestibility in experiment 2.

Growth performance of calves fed microbially enhanced soy protein in pelleted starters

Our objective was to determine effects of feeding calves pelleted starters with microbially enhanced (fungi-treated) soy protein (MSP) in replacement of soybean meal (SBM) with different milk replacers (MR). Thirty-six Holstein calves (2 d old; 24 females, 12 males) in individual hutches were used in a 12-wk randomized complete block design study. Treatments were (1) MSP pellets with MR formulated for accelerated growth (28% crude protein, 18% fat; MSPA), (2) SBM pellets with MR formulated for accelerated growth (SBMA), and (3) MSP pellets with conventional MR (20% crude protein, 20% fat; MSPC). Pellets were similar except for 23% MSP or 23% SBM (dry matter basis). Pellets and water were fed ad libitum throughout the study. Feeding rates of MR on a dry matter basis were 0.37kg twice daily during wk 1, 0.45kg twice daily during wk 2 to 5, and 0.45kg once daily during wk 6. Intakes were recorded daily. Body weights, frame size measurements, and jugular blood samples were collected 2 d every 2 wk at 3 h after the morning feeding. Fecal grab samples were collected 5 times per d for 3 d during wk 12 and then composited by calf for analysis of apparent total-tract digestibility of nutrients using acid detergent insoluble ash as an internal marker. Total and starter pellet dry matter intake were greatest for calves fed SBMA and least for MSPC. Calves had similar average daily gain among treatments, but there was a treatment by week interaction and during the last few weeks of the study calves on MSPC had less body weight compared with MSPA or SBMA. Gain-to-feed ratio was similar among treatments; however, there was a treatment by week interaction. Serum glucose was similar among treatments. Plasma urea nitrogen was greatest for calves fed MSPA and least for MSPC. Plasma concentrations of IGF-1 were greatest for calves fed SBMA. Plasma concentrations of triglycerides were greatest for calves fed MSPC. Plasma concentrations of β-hydroxybutyrate had a treatment by time interaction. Treatments had similar total-tract dry matter digestibility, but calves fed MSPC had greater crude protein digestibility than SBMA, with MSPA similar to both. Results demonstrated calves fed pelleted starters with MSP had maintained growth performance with less starter intake compared with SBM.

Effect of purple prairie clover (Dalea purpurea Vent.) hay and its condensed tannins on growth performance, wool growth, nutrient digestibility, blood metabolites and ruminal fermentation in lambs fed total mixed rations

This study evaluated the effects of purple prairie clover (PPC, Dalea purpurea Vent.) hay and its condensed tannins (CT) on feed intake, growth performance, wool growth, nutrient digestibility, blood metabolites and rumen fermentation in lambs fed diets containing PPC and alfalfa hay. Alfalfa and PPC were harvested at similar growth stage, sun-cured to <12% moisture, and stored in a shed for 120 d. Thirty six individually fed lambs were randomly allocated into three groups and fed total mixed ration containing 40% (dry matter (DM) basis) of a pelleted barley grain based concentrate and 60% of alfalfa hay (AH), or 60% PPC hay (PH) or PH supplemented with polyethylene glycol (PH-p) for 77 d. Lambs were fed once daily and weighed bi-weekly. Faeces samples were collected in the 5th wk for 5 d to determine nutrients digestibility using acid insoluble ash as a marker. Lambs were slaughtered at the end of experiment to evaluate the carcass characteristics. Wool yield and quality were measured using a 10cm dye band applied on d 0 and harvested on d 75. Blood samples were collected to analyze serum metabolites and antioxidant enzymes, and rumen fluid was sampled to analyze rumen fermentation products. Lambs fed PH had lower (P<0.01) DM intake than AH or PH-p. Growth performance, wool growth parameters and carcass characteristics did not differ among diets. Lambs fed PH-p had greater (P<0.05–0.001) DM, organic matter (OM), crude protein (CP), neutral detergent fibre (aNDF) and acid detergent fibre (ADF) digestibility than those fed AH, and greater (P<0.05–0.001) CP, aNDF and ADF digestibility than those fed PH diet. Lambs fed PH exhibited greater apparent total tract digestibility of DM (P<0.05) and OM (P<0.05) and tended (P=0.059) to have greater CP digestibility compared to those fed AH. Lambs consuming PH diet had lower (P<0.05) blood urea nitrogen and creatinine than AH and lower (P<0.05) blood glucose and urea than PH-p, but greater (P<0.01) total antioxidant capacity and catalase activity than AH diet. Lambs fed PPC CT had lower (P<0.05) concentrations of ammonia, total VFA, propionate, iso-butyrate, iso-valerate and protozoa. It was concluded that PPC hay had greater nutritive value to alfalfa hay owing to its greater DM, OM and protein digestibility, but did not improve lamb growth.

Nutritional value of raw and micronised field beans (Vicia faba L. var. minor) with and without enzyme supplementation containing tannase for growing chickens

ABSTRACTAn experiment examined the effects of two field bean cultivar samples with different tannin contents, the effect of heat treatment (micronising) and the effect of dietary supplementation of a proprietary enzyme preparation containing tannase, pectinase, and xylanase activities on metabolisable energy (ME), total tract dry matter digestibility (DMD) and ether extract digestibility (EED), nitrogen retention (NR), tannin degradability, gastrointestinal tract (GIT) development, and endogenous mucin losses excretion in broiler chickens. The Control diet contained per kg 221 g crude protein and 12.83 MJ ME. Four additional diets contained 300 g/kg of each of the two untreated or micronised experimental field bean cultivar samples. Each diet was then split into two batches and one of them was supplemented with 3400 units tannase per kg diet resulting in 10 diets in total. Each diet was fed to seven pens with two randomly selected male broilers each. Birds fed the high tannin bean sample had a lower weight gain (p < 0.001), and a lower determined apparent ME (p < 0.05), and DMD (p < 0.001) but a higher tannin degradability (p < 0.001). Compared to the Control diet, feeding field beans increased (p < 0.001) the weights of the proventriculus and gizzard of the birds, and also increased endogenous mucin losses (p < 0.05). Supplementing diets with the tannase-containing enzyme preparation improved dietary ME (p < 0.001), DMD (p < 0.001), NR (p < 0.001) and DEE (p < 0.05), but did not change tannin degradability. Heat treatment of the beans reduced the degradability of condensed tannins and increased endogenous mucin losses (p < 0.05). The differences in the feeding value of the different field bean samples were not improved by heat treatment, but enzyme supplementation improved the feeding value of all diets regardless of the bean samples or heat treatment. Further research is warranted to study the effectiveness of tannase supplementation in poultry diet formulations by dose response trials with purified tannase preparations.

In situ, in vitro and in vivo nutritive value assessment of Barberry leaf as a roughage for goat feeding

This study was carried out to evaluate nutritive value of Berberis vulgaris leaf (BVL) by in situ and in vitro experiments and to investigate the effects of replacing alfalfa hay with BVL on performance, milk composition, blood metabolites and antioxidant capacity of lactating crossbred goats. Rumen dry matter (DM) degradability of BVL was assessed using two fistulated mature goats and incubation of BVL samples at specified times in the rumen. Modified 3-step procedure (TSP) was performed for determination of post-rumen DM digestibility. For the in vivo experiment (during six weeks), 21 lactating crossbred goats (55±15 DIM and 26±2.8kg BW) were randomly allocated to one of three dietary treatments of BVL at levels of 0, 17 and 34% of DM. The results of in situ and in vitro experiments indicated that rumen DM degradability, post-rumen digestibility of DM undigested in the rumen and total tract DM digestibility of BVL were 65.46%, 12.84% and 69.90%, respectively. In vivo results revealed that DMI increased (P<0.05) as BVL level in the diet raised. Also, milk fat increased (P<0.05) with increasing BVL level in the diets, but milk protein, SNF and lactose content were not affected by the diets (P>0.05). Goats fed BVL showed greater antioxidant capacity than goats fed control diet (P<0.05) and no significant difference was found in plasma malondialdehyde (MDA) content (P>0.05). Results of this study revealed that BVL has high nutritional value and might be utilised in diet of lactating goats as an inexpensive alternative roughage.

Feeding distillers dried grains in replacement of forage in limit-fed dairy heifer rations: Effects on growth performance, rumen fermentation, and total-tract digestibility of nutrients

The objective of this study was to determine the effects of increasing dietary concentration of distillers dried grains (DDGS) in dairy heifer rations. A 16-wk randomized complete block design study was conducted using 48 Holstein heifers [199±2 d of age; body weight (BW) 206±2kg] to evaluate effects of dietary treatment on dry matter (DM) intake, average daily gain, growth performance, rumen fermentation, and nutrient digestibility. Treatments were (1) 30% DDGS with the diet fed at 2.65% of BW, (2) 40% DDGS with the diet fed at 2.50% of BW, and (3) 50% DDGS with the diet fed at 2.35% of BW. The remainder of the diet consisted of grass hay and 1.5% mineral mix. Heifers were individually limit-fed using Calan gates. Heifers were weighed every 2 wk and the ration amount offered was adjusted accordingly. Frame measurements and body condition score were recorded every 2wk. Rumen fluid was collected via esophageal tubing during wk 12 and 16 for pH, ammonia N, and volatile fatty acid analysis. Total-tract digestibility of nutrients was evaluated during wk 16 using fecal grab sampling. No treatment by week interactions were found for any of the growth parameters measured, and growth parameters did not differ among treatments. Heifer DM intake linearly decreased with increasing concentrations of DDGS. Body weight and average daily gain were similar among treatments, whereas gain:feed linearly increased across treatments, with a tendency for a treatment by time interaction. As the dietary concentrations of DDGS increased, rumen ammonia N linearly increased. Acetate proportion and acetate:propionate linearly decreased as DDGS increased, whereas propionate linearly increased. There were treatment by time interactions for propionate proportion and acetate:propionate. Increasing dietary concentrations of DDGS linearly increased total-tract digestibility of DM, organic matter, and crude protein. Limit-feeding diets with greater concentrations of DDGS improved gain:feed and total-tract digestibility of DM and crude protein, and maintained frame growth without increasing body condition score. Results demonstrated that replacing forage with DDGS at up to a 50% inclusion rate in limit-fed rations can maintain heifer growth performance.

Effects of partial replacement of corn and alfalfa silage with tall fescue hay on total-tract digestibility and lactation performance in dairy cows

Our objective was to evaluate the effects of replacing either corn or alfalfa silage with tall fescue hay on total-tract neutral detergent fiber (NDF) digestibility and lactation performance in dairy cows. Twenty-four primiparous (75±35 d in milk) and 40 multiparous (68±19 d in milk) Holstein cows were blocked by parity and randomly assigned to 1 of 4 treatment groups in a pen equipped with 32 feeding gates to record intake by cow. Each gate was randomly assigned to 1 treatment group; thus, each cow had access to all 8 gates within the respective treatment and cow was the experimental unit. Treatments were formulated to replace either corn silage (CS) or alfalfa silage (AS) with tall fescue hay (TF) as follows (DM basis): 33% AS and 67% CS (control; 33AS67CS), 60% TF and 40% AS (60TF40AS), 60% TF and 40% CS (60TF40CS), and 33% TF and 67% CS (33TF67CS). The experiment was a 7-wk continuous lactation trial with a 2-wk covariate period. Milk production did not differ among treatments and averaged 40.4 kg/d. Fat yield and concentration and protein yield and concentration did not differ among treatments and averaged 1.58 kg/d, 3.94%, 1.28 kg/d, and 3.15%, respectively. Dry matter intake was greater for 33AS67CS (24.5 kg/d) compared with 60TF40CS (22.1 kg/d) and 33TF67CS (22.7 kg/d), and tended to be greater than 60TF40AS (23.2 kg/d). In vivo total-tract dry matter digestibility did not differ among treatments and averaged 66.2%. In vivo total-tract NDF digestibility was lower for 33AS67CS (37.8%) compared with 60TF40AS (44.4%) and 33TF67CS (45.3%), and similar to 60TF40CS (42.4%). In vivo total-tract NDF digestibility and an estimate of in situ total-tract NDF digestibility were similar between techniques across all treatment diets (42.3 vs. 42.6%, respectively). Inclusion of tall fescue grass hay increased the total-tract NDF digestibility of the diet and has the potential to replace corn silage and alfalfa silage and maintain milk production if economically feasible based on current market prices.

A comparison of the effect of soybeans roasted at different temperatures versus calcium salts of fatty acids on performance and milk fatty acid composition of mid-lactation Holstein cows

To evaluate the effect of soybeans roasted at different temperatures on milk yield and milk fatty acid composition, 8 (4 multiparous and 4 primiparous) mid-lactation Holstein cows (42.9±3 kg/d of milk) were assigned to a replicated 4×4 Latin square design. The control diet (CON) contained lignosulfonate-treated soybean meal (as a source of rumen-undegradable protein) and calcium salts of fatty acids (Ca-FA, as a source of energy). Diets 2, 3, and 4 contained ground soybeans roasted at 115, 130, or 145°C, respectively (as the source of protein and energy). Dry matter intake (DMI) tended to be greater for CON compared with the roasted soybean diets (24.6 vs. 23.3 kg/d). Apparent total-tract digestibilities of dry matter, organic matter, and crude protein were not different among the treatments. Actual and 3.5% fat-corrected milk yield were greater for CON than for the roasted soybean diets. Milk fat was higher for soybeans roasted at 130°C than for those roasted at either 115 or 145°C. No differences were observed between the CON and the roasted soybean diets, or among roasting temperatures, on feed efficiency and nitrogen concentrations in rumen, milk, and plasma. Milk from cows fed roasted soybeans had more long-chain fatty acids and fewer medium-chain fatty acids than milk from cows fed Ca-FA. Compared with milk from cows fed the CON diet, total milk fat contents of conjugated linoleic acid, cis-9,trans-11 conjugated linoleic acid, cis-C18:2, cis-C18:3, and C22:0 were higher for cows fed the roasted soybean diets. Polyunsaturated fatty acids and total unsaturated fatty acids were greater in milk from cows fed roasted soybean diets than in milk from cows fed CON. Concentrations of C16:0 and saturated fatty acids in milk fat were greater for CON than for the roasted soybean diets. Cows fed roasted soybean diets had lower atherogenic and thrombogenic indices than cows fed CON. Milk fatty acid composition did not differ among different roasting temperatures. In summary, results showed that cows fed CON had higher DMI and milk yield than cows fed roasted soybean diets. Among different roasting temperatures (115, 130, and 145°C), soybeans roasted at 115°C led to higher milk production and lower DMI. Cows fed roasted soybeans, regardless of the roasting temperature, had more unsaturated fatty acids in milk. Using roasted soybeans in dairy cow rations could, therefore, improve the health indices of milk for human nutrition.

Feeding fat from distillers dried grains with solubles to dairy heifers: I. Effects on growth performance and total-tract digestibility of nutrients

The objective of this study was to determine if increased dietary fat from dried distillers grains with solubles (DDGS) in diets of growing heifers affected dry matter intake, average daily gain (ADG), growth performance, and nutrient digestibility. Thirty-three Holstein heifers (133±18 d old) were used in a 24-wk randomized complete block design. Treatments were (1) control (CON) containing ground corn and soybean products, (2) low-fat (LFDG) containing low-fat, high-protein DDGS and ground corn, and (3) high-fat (HFDG) with traditional DDGS. All diets contained 39.8% grass hay, 24.8% corn silage, and 1.5% vitamins and minerals. The HFDG diet was formulated to contain 4.8% fat compared with 2.8% in the CON and LFDG diets, which were greater in nonfibrous carbohydrate. Diets had a net energy gain of 1.0Mcal/kg of dry matter and were limit-fed at 2.45% of body weight. Heifers were weighed every 2wk and rations were adjusted accordingly. Heart girth, hip and wither heights, body length, and body condition score were recorded every 2wk. Total-tract digestion of nutrients was evaluated during wk16 using fecal grab sampling and an external marker. No treatments by time interactions were found. Dry matter intakes, body weights, ADG, and gain-to-feed ratio were similar among treatments; however, ADG averaged 0.96kg/d among treatments, which is greater than recommended. All body frame measurements and body condition scores were similar among treatments. Total-tract digestibilities of dry matter and organic matter were not different among treatments. However, crude protein and neutral detergent fiber digestibility were increased in the HFDG diet compared with the CON and LFDG diets. These results demonstrate that using DDGS or low-fat DDGS with corn in growing heifer rations can maintain performance. Utilizing the fat in DDGS as a dietary energy source in replacement of starch from corn did not influence growth performance or negatively affect nutrient digestion.

Impact of water addition, germination, ensiling and their association on sorghum grain nutritive value

The objective of this study was to evaluate the effects of water addition, germination, ensiling and/or their association with respect to chemical composition and nutritive value of dry sorghum grain. Five commercial paddocks of sorghum grain were harvested dry and evaluated for chemical composition, digestion site and in vitro gas production under six treatment conditions: dry ground (dry), soaked for 24h (SG), germinated for 5 days (G), germinated for 5 days and then ensiled for 21 days (G&E), ensiled for 21 days as whole grain (EWG) or ensiled for 21 days as ground grain (EGG). Soaked, EWG and G&E treatments led to a lower starch content compared to dry grains (P<0.05). Reconstituted and ensiled treatments (either as whole or ground grain) decreased the tannin concentration compared to dry grains (P<0.05). The dry matter (DM) digestion site and total tract digestibility were similar among dry grains, G and EWG. However, compared to these treatments, G&E and EGG increased ruminal and total DM digestibility (P<0.05). Total tract DM digestibility did not differ between SG and dry grains; however, SG affected DM digestion site (P<0.05). Starch digestion site and total tract digestibility were similar between dry grains and EGG. Although G&E and EWG had similar total starch digestibility in comparison with dry grains, these treatments affected the digestion site (P<0.05). Soaked and G treatments reduced total tract digestibility and changed the starch digestion site compared to dry grains (P<0.05). In vitro fermentation of dry grains was similar to SG and EWG. Although the total in vitro gas production was less for G&E and EGG than dry grains (P<0.05), these treatments fermented more rapidly than dry grains (P<0.05). The soaking, the germination process, or the ensiling of whole sorghum grain as sole factors, produced changes in the chemical composition but did not improve the nutritive value of sorghum grain. However, the combination of germination and ensiling resulted in changes in the chemical composition and improved the digestibility of sorghum grains. The grinding of grain before reconstitution and ensiling is an alternative to increase the sorghum grain digestibility and nutritive value.

Effects of partial replacement of dietary starch from barley or corn with lactose on ruminal function, short-chain fatty acid absorption, nitrogen utilization, and production performance of dairy cows

In cows fed diets based on corn-alfalfa silage, replacing starch with sugar improves milk production. Although the rate of ruminal fermentation of sugar is more rapid than that of starch, evidence has been found that feeding sugar as a partial replacement for starch does not negatively affect ruminal pH despite increasing diet fermentability. The mechanism(s) for this desirable response are unknown. Our objective was to determine the effects of replacing barley or corn starch with lactose (as dried whey permeate; DWP) on ruminal function, short-chain fatty acid (SCFA) absorption, and nitrogen (N) utilization in dairy cows. Eight lactating cows were used in a replicated 4×4 Latin square design with 28-d periods and source of starch (barley vs. corn) and level of DWP (0 vs. 6%, DM basis) as treatment factors. Four cows in 1 Latin square were ruminally cannulated for the measurement of ruminal function, SCFA absorption, and N utilization. Dry matter intake and milk and milk component yields did not differ with diet. The dietary addition of DWP tended to increase ruminal butyrate concentration (13.6 vs. 12.2mmol/L), and increased the Cl−-competitive absorption rates for acetate and propionate. There was no sugar effect on minimum ruminal pH, and the duration and area when ruminal pH was below 5.8. Minimum ruminal pH tended to be lower in cows fed barley compared with those fed corn (5.47 vs. 5.61). The duration when ruminal pH was below pH 5.8 tended to be shorter (186 vs. 235min/d), whereas the area (pH×min/d) that pH was below 5.8 was smaller (47 vs. 111) on the corn than barley diets. Cows fed the high- compared with the low-sugar diet had lower ruminal NH3-N concentration. Feeding the high-sugar diet tended to increase apparent total-tract digestibility of dry matter and organic matters and increased apparent total-tract digestibility of fat. Apparent total-tract digestibility of N tended to be greater in cows fed barley compared with those fed corn, whereas apparent total-tract digestibility of acid-digestible fiber was greater in cows fed corn compared with those fed barley. In conclusion, partially replacing dietary corn or barley starch with sugar upregulated ruminal acetate and propionate absorption, suggesting that the mechanisms for the attenuation of ruminal acidosis when sugar is fed is partly mediated via increased SCFA absorption.

The effect of hybrid type and dietary proportions of corn silage on the lactation performance of high-producing dairy cows

We evaluated the effects of corn silage hybrids [control vs. brown midrib (BMR)] and the proportion of corn silage in rations on the performance of high-producing dairy cows. The chemical composition of the corn silages was similar except for lignin, which was higher in the control hybrid [3.09%, dry matter (DM) basis] compared with the BMR hybrid (2.19%). The 30-h in vitro neutral detergent fiber (NDF) digestibility was also higher (62.8% of NDF) in the BMR hybrid than in the control hybrid (52.2%). Twenty-seven Holstein cows were fed 1 of 3 diets comprising 62% forage and 38% concentrate (DM basis) containing 35% (DM basis) corn silage from the control hybrid (NLO), 35% of the BMR hybrid (BLO), or 50% of the BMR (BHI). Cows were fed the diets in a replicated 3×3 Latin square design with 28-d periods. Intake of DM was similar among treatments but milk production was greater for cows fed BLO (50.1kg/d) and BHI (51.1kg/d) than for NLO (47.9kg/d). Milk fat percentage was lower for cows fed BHI (3.37%) than for those fed BLO (3.55%) and NLO (3.56%) but yield of milk fat was similar among treatments. Yield and percentage of milk protein was higher for cows in BHI compared with NLO. The concentration of milk urea N was lower in cows fed BHI (14.0mg/dL) than in those fed NLO (14.7mg/dL) and intermediate for BLO (14.5mg/dL). The yield of 3.5% fat-corrected milk was higher in cows fed BLO (50.2kg/d) than in NLO (48.2kg/d) and was intermediate for BHI (49.8kg/d). The total-tract digestibility of dietary DM, organic matter, starch, and crude protein was lower for cows in NLO compared with the other treatments. The total-tract digestibility of NDF was highest for BHI (54.4%), intermediate for BLO (50.9%), and lowest for NLO (43.2%). We conclude that BMR corn silage can be included in rations at moderate and high proportions of a total ration, resulting in high levels of milk production.

Effects of rumen-protected γ-aminobutyric acid on performance and nutrient digestibility in heat-stressed dairy cows

This experiment was conducted to investigate the effects of rumen-protected γ-aminobutyric acid (GABA) on performance and nutrient digestibility in heat-stressed dairy cows. Sixty Holstein dairy cows (141±15 d in milk, 35.9±4.3kg of milk/d, and parity 2.0±1.1) were randomly assigned to 1 of 4 treatments according to a completely randomized block design. Treatments consisted of 0 (control), 40, 80, or 120mg of true GABA/kg of dry matter (DM). The trial lasted 10wk. The average temperature-humidity indices at 0700, 1400, and 2200h were 78.4, 80.2, and 78.7, respectively. Rectal temperatures decreased linearly at 0700, 1400, and 2200h with increasing GABA concentration. Supplementation of GABA had no effect on respiration rates at any time point. Dry matter intake, energy-corrected milk, 4% fat-corrected milk, and milk fat yield tended to increase linearly with increasing GABA concentration. Supplementation of GABA affected, in a quadratic manner, milk protein and lactose concentrations, and milk protein yield, and the peak values were reached at a dose of 40mg of GABA/kg. Milk urea nitrogen concentration responded quadratically. Total solids content increased linearly with increasing GABA concentration. Supplementation of GABA had no effect on milk yield, lactose production, total solids, milk fat concentration, somatic cell score, or feed efficiency. Apparent total-tract digestibilities of DM, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber were similar among treatments. These results indicate that rumen-protected GABA supplementation to dairy cows can alleviate heat stress by reducing rectal temperature, increase DM intake and milk production, and improve milk composition. The appropriate supplemental GABA level for heat-stressed dairy cows is 40mg/kg of DM.

Effects of including alfalfa hay cut in the afternoon or morning at three stages of maturity in high concentrate rations on dairy cows performance, diet digestibility and feeding behavior

Stage of maturity (SM) and cutting time (CT) are important factors affecting the feeding value of alfalfa hay in ruminants. No data is currently available about the effects of including alfalfa hay cut at different CT and SM in total mixed rations (TMR) containing high levels of concentrates on dairy cows performance. The objective of this study was to investigate the effects of including 200g/kg dry matter (DM) alfalfa hay cut at two CT (18:00 and 06:00h) and three SM (early bud, late bud and early flower) in a TMR with 650g/kg DM concentrates and 150g/kg DM barley silage on dairy cows performance, diet digestibility and feeding behavior. Eighteen cows were used in a cyclic change over design with six treatments (2 CT×3 SM) in three 21d periods. Leaf:stem ratio, crude protein (CP) and soluble carbohydrate (SC) concentration of alfalfa hay decreased with advancing maturity. Including alfalfa hay with advancing maturity in the TMR decreased CP intake (kg/d) and fecal N (g/100g DM) concentration in dairy cows (P<0.05). Neutral detergent insoluble CP (NDICP) and acid detergent fiber (ADF) of alfalfa hay, mean particle size and physically effective factor of TMR and eating behavior (min/kg DMI) of dairy cows increased with advancing alfalfa hay maturity (P<0.05). Cutting alfalfa hay in the afternoon vs. morning increased leaf:stem ratio, leaf content and SC concentration (P<0.05). Feeding TMR with afternoon cut alfalfa hay to dairy cows increased apparent total tract digestibility of DM, organic matter (OM) and CP and serum total protein and decreased fecal nitrogen production (N; g/d), fecal N:milk N ratio (P<0.05) and tended to decrease fecal N concentration (g/100g DM; P<0.10). At the early bud and early flower stage, afternoon cutting vs. morning cutting increased DM, OM and CP digestibility, serum total protein and decreased fecal nitrogen production (g/d) in dairy cows. At the late bud stage, afternoon cutting vs. morning cutting improved milk lactose and total solid non-fat yield (SNF; kg/d; P<0.05). In general, alfalfa hay CT at different SM had more effect on nutrient digestibility and N metabolism than on animal production. In conclusion, stage of maturity of alfalfa hay included in TMR did not greatly affect dairy cow performance when it was included at a rate of 200g/kg DM. The TMRs with alfalfa hay cut in the afternoon improved N efficiency in dairy cows.

Milk production is unaffected by replacing barley or sodium hydroxide wheat with maize cob silage in rations for dairy cows

Starch is an important energy-providing nutrient for dairy cows that is most commonly provided from cereal grains. However, ruminal fermentation of large amounts of easily degradable starch leads to excessive production and accumulation of volatile fatty acids (VFA). VFA not only play a vital role in the energy metabolism of dairy cows but are also the main cause of ruminal acidosis and depressed feed intake. The aim of the present study was to compare maize cob silage (MCS) as an energy supplement in rations for dairy cows with highly rumen-digestible rolled barley and with sodium hydroxide wheat (SHW), which has a higher proportion of by-pass starch than barley. Two studies were carried out: (1) a production study on 45 Danish Holstein cows and (2) an intensive study to determine digestibilities, rumen fermentation patterns and methane emission using three rumen-cannulated Danish Holstein cows. Both studies were organised as a 3×3 Latin square with three experimental periods and three different mixed rations. The rations consisted of grass-clover silage and maize silage (~60% of dry matter (DM)), rapeseed cake, soybean meal, sugar beet pulp and one of three different cereals as a major energy supplement: MCS, SHW or rolled barley (~25% of DM). When MCS replaced barley or SHW as an energy supplement in the mixed rations, it resulted in a lower dry matter intake; however, the apparent total tract digestibilities of DM, organic matter, NDF, starch and protein were not different between treatments. The energy-corrected milk yield was unaffected by treatment. The fat content of the milk on the MCS ration was not different from the SHW ration, whereas it was higher on the barley ration. The protein content of the milk decreased when MCS was used in the ration compared with barley and SHW. From ruminal VFA patterns and pH measures, it appeared that MCS possessed roughage qualities with respect to rumen environment, while at the same time being sufficiently energy rich to replace barley and SHW as a major energy supplement for milk production. The environmental impact, expressed as methane emissions, was not different when comparing MCS, SHW and barley.

Effects of wet corn gluten feed and yellow grease on digestive function of cattle fed steam-flaked corn-based finishing diets

Twelve ruminally cannulated, English-crossbred steers (436±16kg) were used in a completely random experiment to evaluate the influence of dietary wet corn gluten feed (WCGF) and yellow grease (fat) in steam-flaked corn-based finishing diets on diet intake, digestibility, and rumen fermentation characteristics. Treatments consisted of steam-flaked corn-based diets containing the following WCGF/fat combinations: (1) 0g/kg WCGF/30g/kg added fat (STD3), (2) 250g/kg WCGF/0g/kg added fat (WCGF0), and (3) 250g/kg WCGF/30g/kg added fat (WCGF3). Steers fed WCGF3 consumed more (P=0.01) dry matter (DM) than did those fed STD3 or WCGF0 (23.5>18.4=18.8±0.9g/kg of body weight (BW) daily, respectively). Organic matter intake was also greater (P≤0.02) for WCGF3-fed steers than steers fed STD3 and WCGF0 (22.1>17.7=17.8±0.8g/kg BW, respectively). Total tract digestibilities of DM, organic matter (OM), neutral detergent fiber (aNDF), acid detergent fiber (ADF), and crude protein (CP) were not different (P≥0.15) in the 3 groups. Digestion of aNDF was greater in cattle fed WCGF3 and WCGF0 than in those fed STD3 (1.6=1.3>0.8±0.1g/kg BW, respectively). Ruminal fluid dilution rate (0.075>0.057=0.052±0.4/h for WCGF3, WCGF0, and STD3, respectively) and particulate passage rate (0.059>0.042=0.036±0.4/h, for WCGF3, WCGF0, and STD3, respectively) increased (P<0.03) in steers fed WCGF3 compared with those fed WCGF0 and STD3. Ruminal pH was greater (P<0.05) in steers fed WCGF0 than in those fed WCGF3 and STD3 (5.9>5.4=5.3±0.1, respectively). Total ruminal volatile fatty acids (VFA) in WCGF0-fed steers tended to be less (P<0.09) than in steers fed WCGF3 or STD3 (97.8<119.4=122.6±6.8mM, respectively). Ruminal propionate concentration (mol/100mol) tended to be greater (P≤0.06) in steers fed WCGF3 (43.4±2.1) than in those consuming WCGF0 (35.0±2.1) or STD3 (34.0±2.1). The acetate:propionate ration tended to be greater (P<0.09) in steers fed STD3 and WCGF0 than in those fed WCGF3 (1.3=1.3>0.9±0.1, respectively). Supplementing 30g/kg fat to a finishing diet containing 250g/kg WCGF increased DM intake due to faster liquid and particle passage rates, and to increased total tract nutrient digested.

Effects of feeding different levels of dietary fiber through the addition of corn stover on nutrient utilization of dairy heifers precision-fed high and low concentrate diets

The objective of this experiment was to assess the effects of manipulating dietary fiber by replacing corn silage (CS) with lower quality forage as corn stover (CST) when used in high concentrate (HC) and low concentrate (LC) diets for precision-fed dairy heifers. Eight Holstein heifers (335.6±7.41kg of body weight) were randomly assigned to 2 levels of concentrate: HC (20% forage) and LC (80% forage), and to a forage type sequence [0% of forage as corn stover (CST), 100% corn silage (CS); 20% CST, 80% CS; 40% CST, 60% CS; and 60% CST, 40% CS] within concentrate level administered according to a split-plot, 4×4 Latin square design (21-d periods). Heifers fed HC had higher apparent total-tract dry matter digestibility (DMD). Increasing the fiber level by increasing the amount of CST in the diet resulted in a linear decrease of DMD and organic matter digestibility. Heifers fed LC diets had higher neutral detergent fiber (NDF) digestibility and tended to have lower acid detergent fiber (ADF) digestibility than those fed HC diets. Substituting CS with 20% CST resulted in the highest NDF and ADF digestibilities. Digestibility of N was not different, but N retention increased for HC and decreased quadratically for LC diets. Heifers fed HC diets decreased fecal output, and CST linearly increased these parameters. Urine volume tended to be higher for HC-fed heifers, and increasing dietary fiber through CST inclusion tended to decrease urine output. This shift in water excretion resulted in similar total manure output. Total purine derivative excretion did not differ between treatments, but interacted with CST addition, resulting in a linear increase in microbial protein flow to the duodenum in HC-fed heifers and in a linear decrease in LC diets as CST increased. In conclusion, increasing dietary fiber through CST decreased DMD and organic matter digestibility linearly, whereas NDF and ADF digestibility were maximized when 20% CST was added to HC and LC diets. Microbial protein synthesis increased and decreased linearly with CST addition in HC and LC diets, respectively. Retention of N increased and decreased quadratically with CST addition in HC and LC diets, respectively. Total manure excretion was not different between HC or LC diets.

Effect of dried distillers' grain, soybean meal and grain or canola meal and grain-based supplements on forage intake and digestibility

Van De Kerckhove, A. Y., Lardner, H. A., Yu, P., McKinnon J. J. and Walburger, K. 2011. Effect of dried distillers' grain, soybean meal and grain or canola meal and grain-based supplements on forage intake and digestibility. Can. J. Anim. Sci. 91: 123–132. Four ruminally cannulated beef heifers (72 wk of age) were individually fed a basal ration of 75% ground barley straw and 25% ground bromegrass hay [total digestible nutrients=46.3, crude protein (CP)=7.5 (% dry matter (DM))]. Heifers were supplemented with either (1) no supplement (CONT); (2) dried distillers' grains plus solubles [70:30 wheat:corn blend; dried distillers' grains plus solubles (DDGS)]; (3) commercial range pellet (COMM); or (4) barley grain and canola meal (BAR+CM). Forage intake, apparent total tract digestibility, passage rate, rate and extent of forage degradation, rumen pH and rumen ammonia nitrogen were measured. Forage intake, passage rate, and apparent total tract digestibility of DM, neutral detergent fiber, and acid detergent fiber were unaffected (P&gt;0.41) by treatment. Apparent total tract digestibility of CP was increased (P=0.02) with supplements as compared with CONT, but did not differ (P&gt;0.05) among DDGS, COMM, and BAR+CM. Ruminal pH was not affected (P=0.20) by treatment, but rumen ammonia-N was increased (P&lt;0.01) with all three supplements. Potentially degradable and undegradable forage fractions were decreased (P&lt;0.02) and there was a tendency (P=0.06) for the rate of forage DM degradation to increase with supplementation. Supplementing forage diets with either DDGS, grain-soybean-canola- or grain-canola-based supplements did not increase the intake or digestibility of a forage-based diet. More research, however, is required to study the feasibility of feeding these supplements at greater levels with forage-based beef cattle diets.

Fenugreek (Trigonella foenum-graecum L.) as an alternative forage for dairy cows

Fenugreek is a novel forage crop in Canada that is generating interest as an alternative to alfalfa for dairy cows. To evaluate the value of fenugreek haylage relative to alfalfa haylage, six, second lactation Holstein cows (56 ± 8 days in milk), which were fitted with rumen cannulas (10 cm i.d., Bar Diamond Inc., Parma, ID, USA) were used in a replicated three × three Latin square design with 18-day periods. Diets consisting of 400 g/kg haylage, 100 g/kg barley silage and 500 g/kg concentrate on a dry matter (DM) basis were fed once daily for ad libitum intake. The haylage component constituted the dietary treatments: (i) Agriculture and Agri-Food Canada F70 fenugreek (F70), (ii) Crop Development Center Quatro fenugreek (QUAT) and (iii) alfalfa (ALF). DM intake (DMI), milk yield and milk protein and lactose yields were higher (P < 0.001) for cows fed ALF than fenugreek (FEN, average of F70 and QUAT). Milk fat of cows fed FEN contained lower concentrations of saturated, medium-chain and hypercholestrolemic fatty acids (FAs; P < 0.05) than that of cows fed ALF. Apparent total tract digestibility of DM and nutrients was not affected by treatments. Similarly, individual ruminal volatile FA concentrations and rumen pH (5.9) were not affected by treatments. Rumen ammonia–N concentration was higher for FEN than ALF (P < 0.001). Estimates of neutral detergent fiber (NDF) passage rate (P < 0.05) and NDF turnover rate (P < 0.001) in the rumen were higher for ALF than FEN. Our results suggest that although the digestibility of the FEN diets was not different from that of the ALF diet, fenugreek haylage has a lower feeding value than ALF for lactating dairy cows due in part to lower DMI and subsequently lower milk yield.