Total Tract Digestibility Of Crude Protein Research Articles

Slow-releasing urea coated with low-trans vegetable lipids: Effects on lamb performance, nutrient digestibility, nitrogen balance, and blood parameters

The objective of this study was to produce slow-release urea (SRU) coated with low-trans vegetable fat (LTVF) and compare it to uncoated urea (U) in the diet of lambs. The first experiment evaluated LTVF-coated U produced in three different ratios (U: LTVF), 30:70 (SRU30), 40:60 (SRU40), and 50:50 (SRU50). SRU40 had higher (P < 0.05) coating yield (85.5 %) and efficiency (98 %) in comparison to SRU30 (82.9 and 96 %) and SRU50 (83.7 and 96.6 %). SRU40 maintained better thermal stability for retention and slower release of urea (P < 0.05). A second experiment tested SRU40 in 32 intact male Santa Inês lambs (average age: 6 months; average body weight: 17.9 ± 2.01 kg). The lambs were allocated in four treatments: one control diet with 0.5 % U (U0.5 %) and three levels of SRU40 [1.25 % (SRU1.25); 2.0 % (SRU2); 3.0 % (SRU3); dry matter (DM) basis] in a randomized block design to evaluate performance and ingestive behavior. A third experiment evaluated apparent digestibility, nitrogen (N) metabolism, rumen, and blood parameters of 24 intact Santa Inês lambs (average age: 6 months; average body weight: 16 ± 2.2 kg) in a randomized block design with six replications. Including SRU linearly increased ether extract (EE), and non-fiber carbohydrates intake (P < 0.05) but did not change DM, organic matter, crude protein (CP), and neutral detergent fiber assayed with heat stable amylase and expressed excluding residual ash (aNDFom), intake and performance of the lambs (P >0.05). Lambs tended to spend less time ruminating (P = 0.052) and more time eating (P = 0.078) when SRU was included in the diet. The inclusion of SRU in the diet of lambs tended to linearly increase the apparent total tract digestibility of CP (P = 0.078). There was no effect of SRU on N-intake, however, including SRU linearly reduced N-urinary excretion and linearly increased N-retention (P < 0.05). Feeding SRU1.25 % resulted in higher N-retained and lower N-urinary and N-fecal than feeding U0.5 %. Blood urea nitrogen (BUN) and rumen pH decreased linearly with the inclusion of SRU, while NH3-N concentration increased linearly (P < 0.05). Lambs fed SRU1.25 % presented higher BUN and lower NH3-N compared to lambs fed U0.5 % (P < 0.05). N-retained, microbial nitrogen and protein supply linearly increased (P < 0.05) due to the inclusion of SRU in the lambs’ diet. Lambs fed U0.5 % presented the highest (P < 0.05) BUN concentrations at all times after feeding. There was a linear decrease of BUN in lambs fed SRU at 0, 4, and 6-h post-feeding (P < 0.05). LTVF was efficient in coating urea, especially the formulation with 40 % urea and 60 % vegetable fat (SRU40). It is recommended the inclusion of SRU40 in the diet of lambs up to 3 % (total DM basis) as it improves the use of N in the rumen, reducing N-excretion and increasing N-retention, without affecting the performance of the lambs.

The Effects of Harvest Maturity of Eragrostis tef 'Moxie' Hay and Supplemental Energy Source on Forage Utilization in Beef Heifers.

The phenological stage of maturity of grasses and supplementation program can impact forage utilization in grazing beef cattle. However, the potential interaction between harvest maturity of Eragrostis tef (teff) hay and energy supplement source was yet to be fully evaluated. Therefore, our objective was to determine the effects of harvest maturity of teff hay and supplemental energy sources on nutrient intake, apparent total-tract nutrient digestion, nitrogen (N) utilization, and ruminal fermentation characteristics in beef heifers. A split-plot design with teff hay harvest maturity as the whole plot and supplemental energy source as the subplot was administered in a three-period (21 d), three × three Latin square design. Six crossbred beef heifers (804 ± 53.6 kg of body weight; BW) were allocated to two harvest maturities (early- (EH]) or late-heading (LH)) and to two supplemental energy sources (no supplement (CON), or rolled corn grain or beet pulp pellet fed at 0.5% of BW). Data were analyzed using SAS. There was no harvest maturity × energy supplement interaction. Although harvest maturity had no impact on total dry matter intake (DMI), crude protein (CP) intake was greater (p < 0.01) for EH than LH heifers. Total intakes of dry (DM) and organic matter (OM) were also greater (p < 0.01) for supplemented than CON heifers, whereas acid detergent fiber (ADF) intake was greater for beet pulp heifers compared to heifers fed the CON diet and supplemental corn grain. Harvest maturity had no impact on ruminal pH. However, mean ruminal pH was lower (p = 0.04), duration pH < 6.2, and molar proportions of butyrate and branched-chain fatty acids were greater (p ≤ 0.049) for heifers fed corn grain compared to CON and beet pulp diets. Heifers fed EH hay had greater (p ≤ 0.02) apparent total-tract DM, OM, CP, NDF, and ADF digestibility than heifers fed LH hay. Although there was no supplemental energy effect on microbial nitrogen (N) flow, it was greater (p < 0.01) for EH than LH heifers. Apparent N retention, which did not differ, was negative across all diets. In summary, delaying the harvest of teff hay from the EH to LH stage of maturity compromised nutrient supply, which was not attenuated by feeding supplemental corn grain and beet pulp at 0.5% of diet DM. Because N retention was negative across harvest maturity, there might be a need to provide both energy and protein supplements to improve growth performance when feeding teff hay to beef cattle.

PSX-23 Effects of Partial Or Total Nitrogen Replacement of Soybean Meal with Urea on Intake, Digestibility and Nitrogen Balance in Growing Nellore × Red Angus Bulls

Abstract In feedlot systems, feeding non-protein nitrogen sources, such as urea, instead of true protein sources, such as soybean meal (SBM), could be an alternative way to reduce dietary costs. This study aimed to evaluate the effects of partial or total replacement of SBM by urea on feed intake and apparent total-tract digestibility of organic matter (OM) and crude protein (CP), and on nitrogen (N) balance in bulls. Four Nellore × Red Angus crossbred bulls (292 ± 14.6 kg BW) were randomly assigned to treatment in a 4×4 Latin square design. The experimental treatments consisted of different replacement levels of SBM by urea (DM basis): 0% replacement (R-0%); 54% replacement (R-54%); 78% replacement (R-78%); 100% replacement (R-100%). Diets were formulated according to the BR-CORTE system to provide approximately 130 g CP/kg DM. The diets consisted of 20% corn silage and 80% ground corn-based concentrate containing SBM and/or urea+ammonium sulfate, mineral mix, and virginiamycin. Each experimental period was 21 d, with 14 d adaptation, and 4 d of total feces and urine collection. Data were analyzed using the MIXED procedure in SAS and statistical significance was declared at P &amp;lt; 0.05. Dietary treatment did not influence (P &amp;gt; 0.05) OM and CP intake. Apparent total-tract OM and CP digestibility were not influenced (P &amp;gt; 0.05) by dietary treatment. Daily total urinary and fecal N were not influenced (P &amp;gt; 0.05) by dietary treatment. Dietary treatment did not influence (P &amp;gt; 0.05) N retention. Therefore, these data suggest that SBM may be partially or totally replaced by urea as the dietary N source without affecting feed intake, apparent total-tract digestibility, and N balance in Nellore × Red Angus crossbreed young bulls fed a high concentrate diet.

40 Effect of Soybean Meal Inclusion on Grow-Finish Pig Performance and Nitrogen Balance

Abstract Mixed-sex pigs (n = 240 PIC 337×1050; initial BW = 23 ± 4.7 kg) were used to evaluate the effects of soybean meal (SBM) inclusion on the growth performance and nitrogen balance of grow-finish pigs. Pigs were assigned across 60 split-sex pens, and pens were randomly assigned to one of three dietary treatments (10 pens∙treatments-1∙sex-1). Diets were formulated with increasing SBM for an approximate 3% incremental difference in crude protein (CP) between treatments. The treatments were: 1) low SBM (L-SBM) corn-soy diet supplemented with synthetic amino acids, 2) medium SBM diet (M-SBM) with SBM formulated to replace all synthetic lysine and equal to L-SBM in SID lysine, and 3) high SBM diet (H-SBM) contained excess levels of all amino acids. Diets were fed in four feeding phases ranging from approximately 25-50, 51-75, 76-105, and 106-135 kg for phases 1-4, respectively. From phases 1 to 4, SBM inclusion ranged from approximately 26-48% (SID Lys 1.06-1.32%), 19-41% (SID Lys 0.89-1.15%), 15-35% (SID Lys 0.76-1.01%), and 13-29% (SID Lys 0.68-0.86%), respectively. Additionally, diets within each phase were isocaloric. Pig BW and feed intake were measured for each phase to calculate ADG, ADFI, and G:F. On day 66, 18 gilts (n =6/treatment) were placed into metabolism stalls for total urine and feces collection over a 72 h period to assess CP digestibility and nitrogen balance. Pigs were marketed at approximately 134 kg BW, and carcass weight, backfat depth, and loin depth were measured at the harvest facility. Data were subject to ANOVA in SAS 9.4. Pen was the experimental unit, and the results were significant at P ≤ 0.05. Overall (d 0-98) pig ADFI, ADG, or G:F did not differ across treatments (P ≥ 0.202). However, there was a significant diet-by-phase interaction for ADG (P = 0.045) and G:F (P = 0.008), where H-SBM fed pigs grew faster in phase two compared with the M-SBM (1.07 vs. 1.02 kg/d; P = 0.026) or L-SBM (1.07 vs. 1.02 kg/d; P = 0.028) fed pigs. Consequently, in phase two, H-SBM pigs had improved G:F compared with M-SBM (0.47 vs. 0.44; P = 0.005) or L-SBM pigs (0.47 vs. 0.44; P = 0.001). However, these effects were not evident in the other phases. Apparent total tract digestibility of CP and nitrogen retention were similar between treatments (P ≥ 0.762). However, as expected, nitrogen retention as a proportion of intake, linearly decreased (P &amp;lt; 0.001) as SBM inclusion increased, which translated to an approximate 130% increase in total nitrogen excretion in pigs fed H-SBM compared with L-SBM (40.8 vs. 17.7 g/d; P &amp;lt; 0.001). In conclusion, low and high SBM formulations did not alter grow-finish pig overall performance. However, linearly increased nitrogen excretion was reported as SBM levels increased.

Effects of dietary inclusion of 3 Nordic brown macroalgae on enteric methane emission and productivity of dairy cows

Macroalgae are receiving increased attention as antimethanogenic feed additives for cattle, but most in vivo studies are limited to investigating effects of the red macroalgae Asparagopsis spp. Hence, this study aimed to investigate the CH4 mitigating potential of 3 brown macroalgae from the Northern Hemisphere when fed to dairy cows, and to study the effects on feed intake, milk production, feed digestibility, and animal health indicators. The experiment was conducted as a 4 × 4 Latin square design using 4 lactating rumen, duodenal, and ileal cannulated Danish Holstein dairy cows. The cows were fed a total mixed ration (TMR) without any macroalgae or the same TMR diluted with, on a dry matter basis, either 4% ensiled Saccharina latissima, 4% Ascophyllum nodosum (NOD), or 2% Sargassum muticum (MUT). Each period consisted of 14 d of adaptation, 3 d of digesta and blood sampling, and 4 d of gas exchange measurements using respiration chambers. Milk yield and dry matter intake (DMI) were recorded daily. Blood was sampled on d 13 and 16 and analyzed for health status indicators. None of the 3 species affected the CH4 emission. Moreover, milk yield and DMI were also unaffected. Total-tract digestibility of crude protein was significantly lower for NOD compared with other diets, and additionally, the NOD diet also tended to reduce total-tract digestibility of neutral detergent fiber compared with MUT. Blood biomarkers did not indicate negative effects of the dietary inclusion of macroalgae on cow health. In conclusion, none of the 3 brown macroalgae reduced CH4 emission and did not affect DMI and milk production of dairy cows, whereas negative effects on the digestibility of nutrients were observed when A. nodosum was added. None of the diets would be allowed to be fed in commercial dairy herds due to high contents of iodine, cadmium, and arsenic.

Lactation performance, milk fat output, and nutrient digestibility responses to the addition of liquid molasses or yeast culture in dairy cows fed super-conditioned corn

Increased diet fermentability may decrease ruminal pH and fiber digestibility, and increase the flow of trans fatty acids (FA) to the lower tract ultimately leading to milk fat depression. We recently showed that feeding super-conditioned corn, a new method of corn processing (95°C for 6 min in super-conditioner) for ruminants has potential to the reduction in milk fat yield caused by changes in ruminal pH and increased trans FA in milk fat. Supplementing yeast culture (YC) and replacing starch with sugar sources in diet can counteract the negative effects of high fermentable diets by improving ruminal pH and milk fat output. This study aimed to evaluate the effect of feeding beet liquid molasses (LM) and YC on intake and total-tract digestibility of nutrients, milk yield and composition, ruminal fermentation, milk FA profile, and plasma concentrations of glucose, nonesterified FA, β-hydroxybutyric acid, and urea N in early-lactation dairy cows fed high-starch diets containing super-conditioned corn. Twelve primiparous and 18 multiparous Holstein cows (mean ± SD; 67 ± 12 d in milk and 42 ± 2.1 kg of milk at the beginning of the experiment) were blocked by parity, pre-experimental milk yield, and DIM. Cows were used in a randomized complete block design experiment with 14 d as covariate period and 37 d for the experimental period. The following dietary treatments were fed as total mixed rations: (1) control diet (CTRL = no YC or LM supplementation), (2) LM supplementation at 5% of the diet dry matter (MOL diet), and (3) CTRL supplemented with 10 g/d of YC (YST diet). Diets were formulated to be isonitrogenous and isoenergetic. Intake of nutrients and apparent total-tract digestibility of crude protein and starch did not change across treatments. In contrast, cows fed the YST diet had the greatest apparent total-tract digestibility of dry matter, organic matter and neutral detergent fiber. Compared with the CTRL diet, yield of 4% FCM increased by 2.4 and 1.8 kg in cows fed MOL or YST, respectively. The ruminal molar proportions of acetate and butyrate increased in cows fed the YST or MOL diets, respectively, but the proportion of ruminal propionate was not affected by treatments. Milk fat concentration increased by supplementing both LM and YC and the milk yield of total trans-18:1 dropped by 45% and 18% relative to CTRL with MOL or YST diets, respectively. While the MOL diet increased the milk proportion and yield of de novo FA, no treatment effects were observed for the proportion and yield of preformed FA in the milk fat. Apart from β-hydroxybutyric acid concentration in plasma, which was greatest in cows fed MOL, remaining blood metabolites were not affected by treatments. Overall, MOL and YST diets increased 4% FCM and milk fat concentration and reduced the proportion of total trans-18:1 FA in milk fat in cows fed a concentrate based on super-conditioned corn. These responses were associated with increased ruminal pH and the molar proportions of acetate and butyrate with feeding the MOL and YST diets.

Effect of nitrate supplementation, dietary protein supply, and genetic yield index on performance, methane emission, and nitrogen efficiency in dairy cows

The objective was to investigate the effect of nonprotein nitrogen source, dietary protein supply, and genetic yield index on methane emission, N metabolism, and ruminal fermentation in dairy cows. Forty-eight Danish Holstein dairy cows (24 primiparous cows and 24 multiparous cows) were used in a 6 × 4 incomplete Latin square design with 4 periods of 21-d duration. Cows were fed ad libitum with the following 6 experimental diets: diets with low, medium, or high rumen degradable protein (RDP):rumen undegradable protein (RUP) ratio (manipulated by changing the proportion of corn meal, corn gluten meal, and corn gluten feed) combined with either urea or nitrate (10 g NO3-/kg of dry matter) as nonprotein nitrogen source. Samples of ruminal fluid and feces were collected from multiparous cows, and total-tract nutrient digestibility was estimated using TiO2 as flow marker. Milk samples were collected from all 48 cows. Gas emission (CH4, CO2, and H2) was measured by 4 GreenFeed units. We observed no significant interaction between dietary RDP:RUP ratio and nitrate supplementation, and between nitrate supplementation and genetic yield index on CH4 emission (production, yield, intensity). As dietary RDP:RUP ratio increased, intake of crude protein, RDP, and neutral detergent fiber and total-tract digestibility of crude protein linearly increased, and RUP intake linearly decreased. Yield of milk, energy-corrected milk, and milk protein and lactose linearly decreased, whereas milk fat and milk urea nitrogen concentrations linearly increased as dietary RDP:RUP ratio increased. The increase in dietary RDP:RUP ratio resulted in a linear increase in the excretion of total purine derivatives and N in urine, but a linear decrease in N efficiency (milk N in % of N intake). Nitrate supplementation reduced dry matter intake (DMI) and increased total-tract organic matter digestibility compared with urea supplementation. Nitrate supplementation resulted in a greater reduction in DMI and daily CH4 production and a greater increase in daily H2 production in multiparous cows compared with primiparous cows. Nitrate supplementation also showed a greater reduction in milk protein and lactose yield in multiparous cows than in primiparous cows. Milk protein and lactose concentrations were lower for cows receiving nitrate diets compared with cows receiving urea diets. Nitrate supplementation reduced urinary purine derivatives excretion from the rumen, whereas N efficiency tended to increase. Nitrate supplementation reduced proportion of acetate and propionate in ruminal volatile fatty acids. In conclusion, no interaction was observed between dietary RDP:RUP ratio and nitrate supplementation, and no interaction between nitrate supplementation and genetic yield index on CH4 emission (production, yield, intensity) was noted. Nitrate supplementation resulted in a greater reduction in DMI and CH4 production, and a greater increase in H2 production in multiparous cows than in primiparous cows. As the dietary RDP:RUP ratio increased, CH4 emission was unaffected and RDP intake increased, but RUP intake and milk yield decreased. Genetic yield index did not affect CH4 production, yield, or intensity.

Evaluation of fecal sampling time points to estimate apparent nutrient digestibility in lactating Holstein dairy cows.

The aim of this study was the evaluation of nutrient excretion patterns in samples of feces collected every 2 h to define the best sampling protocol for estimation of apparent digestibility. Four multiparous mid-lactation Holstein cows, housed in a tie stall barn and milked twice a day (0800; 1900 h), were enrolled. Dry total mixed ration (TMR) without silages was fed once (0800 h) per day. Feces were sampled every 2 h for 72 h. Each sample was divided in 3 portions: hourly sample sample (8, 10, 12, 14, 16, 18, 20, 22, 00, 2, 4, 6), 8-h composite sample (00-06, 08-14 and 16-22), and a 24-h composite sample. Complete chemical analyses were performed and total tract nutrient digestibility was calculated using undegraded neutral detergent fiber at 240 h of in vitro fermentation (uNDF240h) as a marker. Feeding and rumination patterns were also recorded during the trial. For some parameters, excretion was not constant throughout the day: neutral detergent fiber (aNDFom), undegraded neutral detergent fiber at 24 h of in vitro fermentation (uNDF24h), uDNF240h, total tract crude protein digestibility (TTCPD), total tract neutral detergent fiber digestibility (TTaNDFomD), total tract potentially degraded neutral detergent fiber at 240 h of in vitro fermentation digestibility (TTpdNDF240hD) with minimal values after new TMR delivery and maximal values 12 h after feed delivery. Feeding and ruminating behavior seemed to have an important role in the excretion pattern, due to the pushing and evacuating effect they have. Considering our results, two fecal samples at 12 and 24 h after the TMR delivery are suggested. For one daily sample, 12 h post time of most stable and constant rumination 0000-0600 h, which is also 8 h post feed delivery is suggested.

Effects of particle size and toasting of fava beans and forage source on nutrient digestibility, ruminal fermentation, and metabolizable protein supply in dairy cows.

The objective of this study was to investigate the effects of heat treatment (toasting) and particle size alterations (grinding; rolling) on nutrient utilization, ruminal fermentation, and supply of metabolizable protein (MP), and to study the interaction between processing conditions of fava beans and forage type. Six Danish Holstein dairy cows fitted with ruminal, duodenal, and ileal cannulas were used in a 6 × 4 incomplete Latin square design with 4 periods of 21-d duration. Cows were fed ad libitum with 6 experimental diets: diets high in either grass-clover silage or corn silage were combined with ground untoasted, ground toasted, or rolled untoasted fava beans. Samples of ruminal fluid, digesta from duodenum and ileum, and feces were collected, and nutrient digestibility was estimated using Cr2O3 and TiO2 as flow markers. Diets high in corn silage resulted in higher ruminal pH and higher proportion of propionate in ruminal volatile fatty acids compared with diets high in grass-clover silage. Diets high in corn silage resulted in higher apparent total-tract digestibility of crude protein and starch but lower apparent ruminal and total-tract digestibility of neutral detergent fiber compared with diets high in grass-clover silage. Rolling of fava beans decreased the in situ small intestinal disappearance of rumen-undegradable protein corrected for particle losses. Compared with grinding, rolling of fava beans reduced apparent ruminal digestibility of starch, true ruminal digestibility of organic matter, crude protein, and AA, and small intestinal digestibility of AA and starch. Grinding of fava beans increased apparent ruminal digestibility of neutral detergent fiber and reduced the proportion of propionate in ruminal volatile fatty acids compared with rolling of fava beans. In addition, rolling of fava beans had no effect on MP supply. Toasting of fava beans had no effect on in vivo nutrient digestibility except for an interaction with forage source on apparent ruminal dry matter and organic matter digestibility. Toasting of fava beans did not affect small intestinal digestion of individual and total AA, and therefore failed to increase MP supply. In conclusion, neither replacing grass-clover silage with corn silage, nor toasting nor rolling of fava beans had an effect on supply of MP.

Effects of dietary protease supplementation on growth rate, nutrient digestibility, and intestinal morphology of weaned pigs.

The addition of dietary proteases (PRO) to weaner diets hydrolyzes soybean-based anti-nutritive factors and improves weaned pig’s dietary digestibility and growth performance. Therefore, this study explores the effects of PRO in a lower crude protein (CP) level diet than that in a commercial diet on the growth performance, nutrient digestibility, and intestinal morphology of weaned pigs. A total of 90 weaned pigs were randomly assigned to 3 dietary treatments with 6 pigs per pen and 5 replicated pens per treatment using a randomized complete block design (block = body weight [BW]): 1) a commercial weaner diet as a positive control (PC; phase1 CP = 23.71%; phase2 CP: 22.36%), 2) lower CP diet than PC as a negative control (NC; 0.61% less CP than PC), and 3) an NC diet with 0.02% PRO. Pigs fed PC and PRO had higher (p < 0.05) final BW, average daily gain, and/or gain to feed ratio for the first three weeks and the overall experimental period than NC. The PC and PRO groups had greater (p < 0.05) apparent ileal digestibility of dry matter, CP, and energy than the NC group. Moreover, pigs fed PC and PRO increased (p < 0.05) apparent total tract digestibility of CP compared with those fed NC. In addition, the PRO group had a higher number of goblet cells than the PC and NC groups. However, pig fed PC and PRO increased (p < 0.05) villus height and height to crypt depth ratio in the ileum compared with those fed NC. In conclusion, PRO supplementation in a commercial weaner diet with low CP levels improves growth rate and nutrient digestibility by modulating the intestinal morphology of weaned pigs.

Comparison of methods to estimate ruminal degradation and intestinal digestibility of protein in hydrolyzed feather meal with or without blood

Hydrolyzed feather meal (HFM) is a feedstuff high in rumen undegraded protein (RUP) that can be used as an effective source of metabolizable protein for dairy cattle. Because the production process may vary, the rumen degradability and intestinal digestibility of HFM may also vary. Additionally, some processes may incorporate additional blood into the final product to result in feather meal with poultry blood. To determine the rumen degradability and intestinal digestibility of these products, several laboratory assays can be used; the common assays are the mobile bag (MOB), modified three-step (MTS), and Ross (ROS) assays. Although all 3 assays determine RUP digestibility, they vary in whether they are performed in situ, in vitro, or both. The objective of this study was to evaluate the ruminal degradability and intestinal digestibility of HFM originating from processes that differ in their inclusion of blood, and to compare the MOB, MTS, and ROS assays. Ten samples of HFM, which were identified by the suppliers as HFM with little blood (n = 5) and with more blood (n = 5), were spot-sampled, collected from 10 production plants across the United States, and subjected to all 3 assays. Assay type had an effect on RUP, total-tract crude protein (CP) digestibility, and the amount of RUP digested. A significant effect was observed on RDP and RUP concentrations for blood inclusion; no effect was detected for total-tract CP digestibility. We found no difference in RUP digestibility for assay or blood inclusion. There was also no interaction of the effect of assay or blood inclusion. Results suggest that even though there are differences in chemical composition in HFM associated with the inclusion of blood, such as ash and crude fat, few if any differences are observed in intestinal digestion of protein. Although the assays varied in their estimates of rumen undegraded protein, MOB and MTS yielded the most similar values. However, all 3 assays resulted in similar estimates of RUP digestibility.

Effect of Chitosan Inclusion and Dietary Crude Protein Level on Nutrient Intake and Digestibility, Ruminal Fermentation, and N Excretion in Beef Heifers Offered a Grass Silage Based Diet

Simple SummaryThe level of crude protein offered to beef cattle has an impact on the level of nitrogen excreted into the environment, contributing towards ammonia emissions, which have a negative impact on terrestrial and aquatic ecosystems as well as air pollution. The aim of this study was to investigate the effects of including chitosan with different levels of crude protein on nutrient intake and digestibility, rumen fermentation, and nitrogen excretion in beef heifers offered a grass silage-based diet. Chitosan inclusion reduced nutrient digestibility, whereas feeding the high crude protein diet increased the apparent digestibility of crude protein. Feeding the high crude protein diet increased the amount of nitrogen excreted in the urine, while chitosan inclusion increased the amount of nitrogen excreted in the faeces. The chitosan used in this study had a negative effect on dry matter, organic matter, and crude protein digestibility, while feeding the high crude protein diet increased the amount of nitrogen excreted in the urine, which has a negative effect on the environment.Nitrogen (N) use efficiency in beef cattle is low (10–20%), resulting in large amounts of N excreted into the environment. The objective of this study was to evaluate the effects of chitosan inclusion and dietary crude protein (CP) level on nutrient intake and digestibility, ruminal fermentation, and N excretion in beef heifers. Eight Belgian Blue × Holstein Friesian cross beef heifers (752 ± 52 kg BW) were used in a 4 × 4 Latin square with a 2 × 2 factorial design. Factors were dietary CP concentration—high CP, 16% (HP) or low CP, 12% (LP)—and chitosan inclusion—0 or 10 g kg−1 dry matter (DM) offered at 50:50 forage concentrate ratio on a dry matter (DM) basis. Apparent total tract digestibility of DM, organic matter (OM), and CP were reduced (p < 0.001) with chitosan inclusion, whereas offering the HP diets increased apparent total tract digestibility of CP (p < 0.001). Offering the HP diets increased urinary N excretion (p < 0.001), while chitosan inclusion increased N excretion in faeces (p < 0.05). Ruminal pH was increased with chitosan inclusion (p < 0.01). There was a CP × chitosan interaction for rumen ammonia (NH3) concentrations (p < 0.05). Including chitosan in the HP diets increased ruminal NH3 concentration while having no effect on the LP diets. Urinary N excretion was increased with increased levels of CP, but chitosan inclusion increased the quantity of N excreted in the faeces.

Production performance and nitrogen metabolism in dairy cows fed supplemental blends of rumen undegradable protein and rumen-protected amino acids in low- compared with high-protein diets containing corn distillers grains

Feeding corn dried distillers grains with solubles (DDGS) in low crude protein (CP) diets could limit N waste in lactating cows. However, it also could possibly reduce metabolizable AA supply, especially Lys, and compromise milk production. Therefore, the objective of this study was to evaluate the effects of feeding supplemental blends of rumen undegradable protein (RUP) and rumen-protected (RP) AA in a low compared with high CP diet containing corn DDGS on milk production and selected measures of N utilization. Six multiparous Holstein cows (619.3 ± 49.8 kg of body weight; 26.8 ± 6.2 d in milk) were subjected to a split-plot, 3 × 3 Latin square design (21-d periods) with dietary CP content [low (14.6%; LP) or high (16.6%; HP)] as the whole-plot factor, and blend of RUP and RP-AA [control (CON), no supplement; blend A (0.11 kg/cow per d); or blend B (0.45 kg/cow per d)] as the sub-plot factor. All diets contained 10% corn DDGS; blends of RUP and RP-AA were top-dressed during morning feeding. There was no dietary CP content × supplemental blend interaction for all measured variables. Nutrient (dry matter, organic matter, neutral detergent fiber, acid detergent fiber, and CP), milk and milk component yields, and feed and apparent N efficiency did not differ for cows fed the low- compared with the high-protein diet. However, apparent total-tract CP digestibility, blood and milk urea-N concentrations, and urinary excretion (g/d) of N and urea-N were lower for cows fed the low-protein compared with the high-protein diet. There was no supplemental blend effect on nutrient intake and apparent total-tract digestibility, and milk and milk component yields. Except for a tendency for total urinary purine derivative excretion and microbial N flow to be lower for cows fed blend B compared with CON but not blend A, there was no supplemental blend effect on measures of N utilization. Both dietary CP content and supplemental blend of RUP and RP-AA had a marginal effect on the plasma free AA profile. In summary, reducing dietary CP content in diets containing corn DDGS had no effect on lactation performance, possibly accounting for the lack of a positive response following the provision of supplemental blends of RUP and RP-AA. However, reducing dietary CP content resulted in a decrease in blood and milk urea-N concentrations, and urinary excretion of N and urea-N, suggestive of an improvement in the efficiency of N use.

Effects of a high-protein corn product compared with soy and canola protein sources on nutrient digestibility and production responses in mid-lactation dairy cows

An experiment was conducted to assess the effects of a novel and proprietary high-protein corn product [56% crude protein (CP)] relative to other common sources of protein on the lactation performance of dairy cows. Twenty-four Holstein cows (620 ± 47.7 kg of body weight, 111 ± 34 d in milk, 2.28 ± 0.46 lactations; mean ± standard deviation) were randomly assigned to treatment sequence in a replicated 4 × 4 Latin square design balanced for carryover effects. Cows were individually fed 1 of 4 diets with a different protein concentrate source during each 28-d period, including soybean meal (SBM), high-protein corn product (HPCP), soybean meal with rumen-bypass soy protein (SBMBP), and canola meal with rumen-bypass soy protein (CANBP). Diets were formulated for equal concentrations of CP and balanced to meet predicted lysine and methionine requirements. The SBM diet was formulated to provide 5.7% rumen-undegradable protein (RUP), whereas SBMBP and CANBP diets were formulated for 6.8% RUP to match HPCP. Data were analyzed using mixed models with the fixed effects of treatment, period, square, the interactions of treatment and period and of treatment and square, and the random effect of cow. The CANBP diet increased dry matter intake (DMI) compared with SBM and HPCP. Treatment affected milk yield, as SBMBP and CANBP increased yield compared with SBM, but HPCP decreased milk yield compared with all treatments. The HPCP diet reduced CP intake as a percent of total DMI and increased the CP content of orts, indicative of selection against HPCP. The HPCP diet also decreased apparent total-tract and CP digestibility, leading to less urine nitrogen excretion and greater fecal nitrogen output. The SBMBP and CANBP diets performed similarly in nearly every variable measured, except that SBMBP increased milk urea nitrogen. In conclusion, the HPCP diet reduced yield of milk and milk components, likely because of reduced apparent total-tract dry matter and CP digestibility.

Production, milk iodine, and nutrient utilization in Jersey cows supplemented with the brown seaweed Ascophyllum nodosum (kelp meal) during the grazing season

Kelp meal (KM) is a supplement made from the brown seaweed Ascophyllum nodosum, known to bioaccumulate iodine (I) and to be the richest source of phlorotannins, which can inhibit ruminal proteolysis and microbial growth. The objective of this study was to investigate the effects of KM on production, milk I, concentrations of blood metabolites, apparent total-tract digestibility of nutrients, and CH4 emissions in grazing dairy cows. Eight multiparous Jersey cows averaging (mean ± SD) 175 ± 60 d in milk and 12 primiparous Jersey cows averaging 142 ± 47 d in milk at the beginning of the study were assigned to either 0 g/d of KM (control diet, CTRL) or 113 g/d of KM (brown seaweed diet, BSW) in a randomized complete block design. Diets were formulated to yield a 70:30 forage-to-concentrate ratio and consisted of (dry matter basis): 48% cool-season perennial herbage and 52% partial TMR (pTMR). Each experimental period (n = 3) lasted 28 d, with data and sample collection taking place during the last 7 d of each period. Cows had approximately 16.5 h of access to pasture daily. Herbage dry matter intake increased, and total dry matter intake tended to increase in cows fed BSW versus the CTRL diet. Milk yield and concentrations and yields of milk components were not affected by diets. Similarly, blood concentrations of cortisol, glucose, fatty acids, and thyroxine did not change with feeding CTRL or BSW. However, a diet × period interaction was observed for milk I concentration; cows offered the BSW diet had greater milk I concentration during periods 1, 2, and 3, but the largest difference between BSW and CTRL was observed in period 2 (579 vs. 111 µg/L, respectively). Except for period 2, the concentration of milk I in cows fed KM did not exceed the 500 µg/L threshold recommended for human consumption. Diet × period interactions were also found for serum triiodothyronine concentration, total-tract digestibilities of crude protein and acid detergent fiber, CH4 production, and urinary excretion of purine derivatives. Overall, the lack of KM effects on milk yield and concentrations and yields of milk components indicate that dairy producers should consider costs before making KM supplementation decisions during the grazing season. Future research is needed to evaluate the concentration of I in retail organic milk because of the high prevalence of KM supplementation in northeastern and midwestern US organic dairies and possibly in other regions of the country.

Faba bean (Vicia faba) inclusion in dairy cow diets: Effect on nutrient digestion, rumen fermentation, nitrogen utilization, methane production, and milk performance

The objective of this study was to determine the effect of replacing on isonitrogenous and isoenergetic basis soybean meal (SBM) and corn grain with ground or rolled faba bean (FB; Vicia faba major var. Baie-Saint-Paul) in dairy cow diets (17% of diet dry matter) on nutrient digestion, rumen fermentation, N utilization, methane production, and milk performance. For this purpose, 9 lactating cows were used in a replicated 3 × 3 Latin square design (35-d period) and fed (ad libitum) a total mixed ration (forage:concentrate ratio = 59:41 on a dry matter basis). In the concentrate portion, SBM and corn grain (control diet) were completely and partially replaced, respectively, with either ground or rolled FB. Ruminal degradability (in sacco) of crude protein was higher for ground FB (79.4%) compared with SBM (53.3%) and rolled FB (53.2%). Including FB in the diet did not affect dry matter intake, milk production, and milk composition. Experimental treatment had no effect on total volatile fatty acid concentration, acetate-to-propionate ratio, and protozoa numbers. Compared with cows fed the control diet, ruminal NH3 concentration increased and tended to increase for cows fed ground FB and rolled FB, respectively; however, we found no difference in ruminal NH3 concentration between the 2 processed FB. Apparent total-tract digestibility of crude protein was similar between cows fed the control diet and cows fed rolled FB and tended to increase for cows fed ground FB compared with cows fed the control diet. Feeding rolled FB decreased CP digestibility compared with feeding ground FB. Urinary and manure (feces + urine) N excretion (g/d or as a proportion of N intake) were not affected by the inclusion of FB in the diet. Enteric CH4 production was similar among the experimental diets. Results from this study show that including FB (17% of dietary dry matter) at the expense of SBM and corn grain in the diet had no effect on milk production, N excretion, and enteric CH4 production of dairy cows.

Effect of grain type and dried distillers grains plus solubles oil concentration on site of digestion in cattle fed finishing diets

The objective of this experiment was to determine the effects of grain type (rolled corn vs. rolled barley) and oil concentration of dried corn distillers grains plus solubles (DDGS; moderate = 7.9% vs. low = 4.5% ether extract) on site of digestion. Seven ruminally and duodenally cannulated Holstein steers (716 ± 8.9 kg) were used in a 4 × 7 Youden square with experimental periods of 24 d. True ruminal organic matter (OM) and crude protein (CP) digestibility (% of intake) as well as intestinal (% of entering duodenum) and total tract starch digestibility was greater (P ≤ 0.03) in steers fed diets containing barley than in steers fed diets containing corn. Ruminal disappearance and ruminal, intestinal, and total tract OM, CP, and starch digestibility were not influenced (P ≥ 0.11) by feeding diets containing DDGS with differing oil concentration. Total tract lipid digestibility (%) was greater (P &lt; 0.001) in steers fed diets containing moderate-oil DDGS than low-oil DDGS. These data indicate that including a low-oil DDGS, as compared with a moderate-oil DDGS, in finishing diets containing rolled corn or rolled barley does not influence intake or site of digestion of nonlipid components.

Effect of grain- or by-product-based concentrate fed with early- or late-harvested first-cut grass silage on dairy cow performance

This study compared the effects of a grain-based conventional concentrate (GC) and a concentrate based on agro-industrial by-products (BC), fed with grass silage harvested at early (ES) or late (LS) maturity stage, on dairy performance, CH4 and CO2 emissions, and metabolic status of dairy cows. Twenty lactating Nordic Red cows averaging 81 d in milk and 31.9 kg of milk/d pre-trial were assigned to a replicated 4 × 4 Latin square design. Dietary treatments were in a 2 × 2 factorial arrangement. The silages were harvested 2 wk apart from the same primary growth grass ley. The GC was made from oats, barley and wheat, and soybean meal, whereas the BC contained sugar beet pulp, wheat bran, canola meal, distillers dried grains, palm kernel expeller, and molasses. The diets were fed ad libitum as total mixed rations and were formulated from 661 g/kg of silage, 326 g/kg of concentrate, and 13 g/kg of minerals on a dry matter basis. The BC supplied the cows with less energy. Despite this, milk yield and composition were unaffected by concentrate type, except that milk protein was 0.7 g/kg lower in cows fed BC than in those fed GC. These results were accompanied by a 44 g/kg decrease in total-tract digestibility of crude protein and a 54 g/kg increase in neutral detergent fiber digestibility for cows fed BC. Cows fed ES on average consumed 2 kg/d more dry matter and yielded 3.5 kg/d more milk, 149 g/d more protein, and 141 g/d more fat than cows fed LS. There were few interaction effects between concentrate and silage sources on daily intake and dairy performance. However, edible feed conversion ratio (human-edible output in animal/potentially human-edible feed) showed greater improvements with ES than LS when replacing GC with BC. Feeding diets with late-cut silage generally reduced digestibility and energy utilization efficiency, but improved N utilization efficiency. Feeding LS also led to greater CH4 yield and CH4/CO2 ratio, and higher plasma concentration of nonesterified fatty acids. Plasma parameters reflecting energy metabolism and inflammation were all within the normal ranges, indicating that the cows were in good health during the experiment. In conclusion, a conventional concentrate can be replaced by agro-industrial by-products without compromising production in early lactation dairy cows. However, silage maturity has a stronger effect on the production traits of dairy cows than type of concentrate.

Effect of milk replacer feeding rate, age at weaning, and method of reducing milk replacer to weaning on digestion, performance, rumination, and activity in dairy calves to 4 months of age

The objectives of this study were to evaluate calf performance, diet digestibility, and rumination activity when feeding 4 milk replacer (MR) feeding programs. Male Holstein calves (n = 96; 43 ± 1.2 kg of body weight; 1 to 2 d of age) were housed in individual pens for 56 d. Calves were fed a common MR [25% crude protein (CP), 17% fat, dry matter (DM) basis]. Feeding programs were (1) 0.66 kg of DM/d of MR and weaning at 42 d (MOD6); (2) up to 1.09 kg of DM/d of MR weaned at 42 d (HIGH6); (3) up to 1.09 kg of DM/d of MR weaned at 53 d (HIGH8); and (4) up to 1.09 kg of DM/d of MR and gradually weaned from d 35 to 53 (GRAD8). Calves were fed a textured starter containing whole grains with 20% CP and 37% starch (DM basis). From 38 to 56 d of age, 4 calves/treatment had ear tag accelerometers fitted to provide measurements for eating, rumination, and activity. Calves were moved into groups by treatment (4 calves/pen) at 56 d and fed the same starter blended with 5% hay. Fecal samples were collected for individual calves between d 31 to 35, 45 to49 (MOD6 and HIGH6 only), and 56 to 60 from 5 calves/treatment. Fecal samples were collected by pen from d 80 to 84 and 108 to 112. Data were analyzed as a randomized complete block design with repeated measures when appropriate. Preplanned contrasts of MOD6 versus others, HIGH6 versus HIGH8, and HIGH8 versus GRAD8 were used to separate the means. Calves fed MOD6 were 3.4 kg lighter at 56 d than calves fed other treatments. Starter intake was greatest for MOD6 compared with other treatments (0.78 vs. 0.43 kg/d) from 0 to 56 d. Hip width and body condition score change from 0 to 56 d were similar among treatments. Average time ruminating, eating, and activity did not differ among treatments. Total-tract digestibility of DM, OM, CP, and fat were least for calves fed MOD6 versus other treatments on d 35, whereas NDF and starch digestibility were greatest for MOD6 at d 35. Digestibility of ADF and NDF were also greatest for MOD6 at d 49 (compared with HIGH6 only) and 60. From d 56 to 112, calves previously fed MOD6 had greater ADG versus other treatments. At 84 d, DM, OM, CP, NDF, ADF, and fat digestibility were greatest for calves fed MOD6 versus others. Calves fed HIGH6 and GRAD8 had greater digestibility of NDF and ADF compared with HIGH8 at 84 d. At 112 d, digestibility was similar among treatments. Calves were not different in BW and hip width at 112 d, with growth driven by less digestion of DM and fiber around and after weaning for calves fed >0.66 kg of MR. Gradual weaning did improve postweaning digestion.

Daily and alternate day supplementation of Moringa oleifera leaf meal or soyabean meal to lambs receiving oat hay

We hypothesized that Moringa oleifera foliage which is high in crude protein and almost free in main secondary compounds could replace soyabean meal used in supplementation strategies of livestock. Therefore, this experiment aimed to evaluate the effect of daily and alternate day supplementation of Moringa leaf meal (MLM) or soybean meal (SBM) to sheep on intake and digestion and glucose, protein and urea in blood plasma. Twenty Barbarine male lambs (average initial body weight, 27.3±3.0kg), were randomly divided into four groups of five lambs each. They were adapted for 22 days to dietary treatments before starting a 6-day total collection period. All animals consumed oat hay ad libitum supplemented with concentrates composed of barley grain only (C-BAR) or mixed with SBM (C-SBM), or MLM (C-MLM) as protein sources. Groups 1 and 2 received daily C-SBM and C-MLM, respectively. However, groups 3 and 4 had access to concentrates containing the protein sources (C-SBM and C-MLM) with alternate day that means they received for one day these concentrates and in the following day they received barley grain only (C-BAR). Soybean meal and MLM incorporation in concentrates had similar effects (P>0.05) on water, hay, and digestible organic matter (OM) intakes and DM, organic matter (OM) and neutral detergent fiber (NDF) digestibility. Daily substitution of SBM by MLM increased (P=0.024) crude protein (CP) intake and apparent total tract digestibility. However, the alternate day supplementation decreased apparent total tract CP digestibility but increased CP intake for SBM treatment. The concentration of ruminal ammonia nitrogen before feeding was higher (P=0.012) in groups 1 and 3 than in the other groups. The concentration of blood glucose was similar (P>0.05) among treatments. However, lambs receiving C-SBM exhibited highest concentrations of protein (P=0.039) and urea (P=0.001) in the blood. It is concluded that MLM administered at two day-intervals had similar effects on feed intake, digestion and blood metabolites to SBM incorporated in concentrate distributed to sheep receiving oat hay.