Crude Protein Supply Research Articles

Impact of dietary supplementation with β-alanine on the rumen microbial crude protein supply, nutrient digestibility and nitrogen retention in beef steers elucidated through sequencing the rumen bacterial community

This study investigated the effects of β-alanine (β-Ala) on rumen fermentation, nutrient digestibility, nitrogen (N) metabolism, plasma biochemical parameters, and rumen bacterial communities in beef steers. Six steers with initial liveweight of 252.8 ± 5.2 kg and 3 treatments of supplementing with 0, 30, or 60 g β-Ala per day to basal diet were allocated in a replicated 3 × 3 Latin square design. Each experimental period was 20 d, of which the first 15 d were for adaptation and the subsequent 5 d were for sampling. The results showed that β-Ala linearly increased the ruminal concentration of microbial crude protein (MCP) (P = 0.005), but it did not affect the ruminal concentrations of ammonia N and total volatile fatty acids (P > 0.10). β-Ala also linearly increased the dry matter (DM) (P = 0.009), organic matter (OM) (P = 0.017) and crude protein (CP) (P = 0.043) digestibility, tended to decrease the acid detergent fiber digestibility (P = 0.077), but it did not affect the neutral detergent fiber digestibility (P = 0.641). β-Ala quadratically increased the relative abundance of ruminal Bacteroidota (P = 0.021) at the phylum level, and increased Prevotella (P = 0.028) and Prevotellaceae_UCG-003 (P = 0.014), and decreased the relative abundance of NK4A214_group (P = 0.009) at the genus level. Feeding steers with β-Ala linearly increased the urinary N (P = 0.006), urea excretions (P = 0.002) and the N retention (P = 0.004), but it did not affect the N utilization efficiency (P = 0.120). β-Ala quadratically increased the plasma concentration of the total antioxidant capacity (P = 0.011) and linearly increased the plasma concentration of insulin-like growth factor-1 (P < 0.001). In summary, dietary supplementation with β-Ala improved the rumen MCP supply and increased the digestibility of DM, OM, CP and the N retention. Further research is necessary to verify the ruminal degradability of β-Ala and to investigate the mechanism of the impact of absorbed β-Ala on the anti-oxidative ability in steers.

Feeding sorghum dry distillers grains plus solubles to early-weaned beef calves

This study evaluated the effect of feeding sorghum dry distillers grains plus solubles (SDDGS) to early-weaned beef calves as an energy/protein source in a sorghum-grain-based diet. Twenty-four castrated Hereford calves (84.6 ± 11.0 kg) were assigned randomly to four rations differing in SDDGS concentrations (0, 130, 260, or 390 g/kg, dry matter [DM] basis), where the SDDGS replaced a mixture of sorghum ground grain (420 g/kg) and soybean meal (580 g/kg) at a balance that ensured a similar supply of crude protein (185 g/kg) and metabolizable energy (12.1 MJ/kg) in the ration. The feeding period lasted for 70 days, with animals individually fed ad libitum in three daily meals. Increasing SDDGS in the diet linearly increased DM intake, fiber and fat intake (P&lt;0.01), without affecting nitrogen intake or DM digestibility (P&gt;0.10). Higher SDDGS did not affect (P&gt;0.10) calves’ BW gain (1.13 kg/d, SE 0.05) or final BW (160.0 kg, SE 8.8), but it did result in a linear drop in gain-to-feed ratio (GF= −0.0012 × + 0.2679; P&lt;0.01). No differences were detected in animal behavior (eating, resting, or ruminating activity) due to treatments (P&gt;0.10). The observed net energy (NE) in the control diet was below the expected value based on feeding standards; as SDDGS replaced a higher proportion of sorghum grain and soybean meal in the control diet, the observed diet NE concentration declined linearly (P&lt;0.01). The highest replacement rate represented a reduction of 15% and 20% in diet NE for maintenance and BW gain, respectively.

Dynamic lactation responses to dietary crude protein oscillation in diets adequate and deficient in metabolizable protein in Holstein cows

Limited research has examined the interaction between dietary crude protein (CP) level and CP feeding pattern. We tested CP level (low protein [LP], 13.8%; high protein [HP], 15.5% CP, dry matter [DM] basis) and CP feeding pattern (OF = oscillating, SF = static) using a 2 × 2 factorial in 16 mid- to late-lactation Holsteins (initially 128 ± 12 d in milk; mean ± SD). Cows ate total mixed rations formulated by exchanging soy hulls and ground corn with solvent soybean meal to keep constant ratios of neutral detergent fiber to starch (1.18:1), rumen-degradable protein to CP (0.61:1), and forage-to-concentrate (1.5:1) in DM. The OF treatments alternated diets every 48 h to vary CP above and below the mean CP level (OF-LP = 13.8% ± 1.8%; OF-HP = 15.5% ± 1.8% CP [DM basis]) whereas diets were constant in SF (SF-LP = 13.8%; SF-HP = 15.5% CP [DM basis]). In four 28-d periods, 8 rumen-cannulated and 8 noncannulated cows formed 2 Latin rectangles. On d 25 to 28 of each period, each cow's feed intake and milk production were recorded, and samples were taken of orts (1×/d) and milk (2×/d). We fit linear mixed models with fixed CP level, CP feeding pattern, and period effects, and a random intercept for cow, computing least squares means and standard errors. Neither CP level, CP feeding pattern, nor the interaction affected DM intake, feed efficiency, or production of milk, fat- and protein-corrected milk (FPCM), fat, true protein, or lactose. Milk urea-N (MUN) yield was lesser for LP. The LP and OF conditions decreased MUN concentration. The CP level tended to interact with CP feeding pattern so that milk protein concentration was greatest for OF-HP. The OF and LP conditions increased the ratio of true protein to MUN yield. Within OF, cosinor mixed models of selected variables showed that cows maintained production of FPCM across dietary changes, but MUN followed a wave-pattern at a 2-d delay relative to dietary changes. A tendency for lesser MUN with OF contradicted prior research and suggested potential differences in urea-N metabolism between OF and SF. Results showed that cows maintained production of economically-relevant components regardless of CP feeding pattern and CP level. Contrary to our hypothesis, the effects of 48-h oscillating CP were mostly consistent across CP levels, suggesting that productivity is resilient to patterned variation in dietary CP over time even when average CP supply is low (13.8% of DM) and despite 48 h restrictions at 12.2% CP.

Extrusion of lupines with or without addition of reducing sugars: Effects on the formation of Maillard reaction compounds, partition of nitrogen and Nε-carboxymethyl-lysine, and performance of dairy cows

The extrusion of leguminous seeds induces the formation of Maillard reaction compounds (MRC) as a product of protein advanced glycation and oxidation, which lowers protein degradability in the rumen. However, the quantitative relationship between the parameters of pretreatment (i.e., addition of reducing sugars) and extrusion, and the formation of MRC has not been established yet. Moreover, the fate of the main stable MRC, Nε-carboxymethyl-lysine (CML), in the excretory routes has never been investigated in ruminants. We aimed to test the effects of the temperature of extrusion of white lupines with or without addition of reducing sugars on the formation of MRC, crude protein (CP) degradability in the rumen, N use efficiency for milk production (milk N/N intake), and performance of dairy cows. Two experiments with a replicated 4 × 4 Latin square design were conducted simultaneously with 16 (3 rumen-cannulated) multiparous Holstein cows to measure indicators of ruminal CP degradability (ruminal NH3 concentration, branched-chain volatile fatty acids), metabolizable protein supply (plasma essential AA concentration), N use efficiency (N isotopic discrimination), and dairy performance. In parallel, apparent total-tract digestibility of dry matter, organic matter, neutral detergent fibers, N, total Lys and CML, and partition of N and CML were measured with 4 cows in both experiments. The diets consisted on a DM basis of 20% raw or extruded lupines and 80% basal mixed ration of corn silage, silage and hay from permanent grasslands, pelleted concentrate, and a vitaminized mineral mix. Expected output temperatures of lupine extrusion were 115°C, 135°C, and 150°C, without and with the addition of reducing sugars before extrusion. The extrusion numerically reduced the in vitro ruminal CP degradability of the lupines, and consequently increased the predicted supply of CP to the small intestine. Nitrogen balance and urinary N excretion did not differ among dietary treatments in either experiment. Milk yield and N use efficiency for milk production increased with extrusion of lupines at 150°C without addition of reducing sugars compared with raw lupines. Nitrogen isotopic discrimination between dietary and animal proteins (the difference between δ15N in plasma and δ15N in the diet) were lower with lupines extruded at 150°C without and with addition of reducing sugars. Regardless of sugar addition, milk true protein yield was not affected, but milk urea concentration and fat:protein ratio were lower with lupines extruded at 150°C than with raw lupines. In the CML partition study, we observed that on average 26% of the apparently digested CML was excreted in urine, and a much lower proportion (0.63% on average) of the apparently digested CML was secreted in milk, with no differences among dietary treatments. In conclusion, we showed that the extrusion of white lupines without or with addition of reducing sugars numerically reduced enzymatic CP degradability, with limited effects on N partition, but increased milk yield and N use efficiency at the highest temperature of extrusion without addition of reducing sugars.

Bamboo forage in Peruvian Amazon: a potential feed for cattle.

During the dry and rainy seasons of the Northeastern Zone of Peru, a chemical characterization of five species of bamboo prevalent in the area (Guadua lynnclarkiae, G. takahashiae, Bambusa vulgaris, G. weberbaueri, and Dendrocalamus asper) was conducted. Then, the effect of supplementing bamboo leaves (0, 20, and 40% inclusion of D. asper) on the intake and live weight gain of 18 Gyr × Holstein heifers was evaluated for 28 days. Among the species evaluated, D. asper has the greatest crude protein (CP) concentration (158-166 g/kg Dry matter- DM), post-ruminal CP supply (127 g/kg DM), and in vitro organic matter digestibility (444-456 g/kg DM) but similar concentrations of crude ash (124 g/kg DM), calcium (2.4-2.8 mg/g), phosphorus (0.7-2.1 mg/g), protein fractions A, B1, B2, B3, C (45, 5, 35, 56, and 17g/kg DM, respectively), rumen-undegraded CP (31% CP), neutral detergent fiber (NDF, 685g/kg DM), and acid detergent fiber (ADF,357 g/kg DM) than the other species evaluated. Dry matter intake was higher in the control treatment and in the 20% bamboo leaf inclusion treatment than in the 40% bamboo inclusion treatment. Intake of CP and NDF decreased with the increase in bamboo inclusion. Despite the differences in DM, CP, and NDF intake, the live weight gain remained similar across treatments. However, there was a greater feed conversion in the 20% bamboo leaf inclusion treatment. During the dry season, bamboo leaves can be used as an alternative supplement at a maximum inclusion of 20% without affecting the live weight gain.

Improving live weight gain in Ongole crossbred bulls through processing of Gliricidia sepium leaf meal and cassava in a supplement concentrate

Formulating rations using locally produced protein and energy sources is an important strategy to increase beef production in developing countries. Gliricidia sepium leaf meal (GLM), dry cassava powder (DCP), soybean hulls (SBH), peanut husks (PH) and palm kernel cake (PKC) in various combinations, were processed either as a mash or a pellet, to produce a concentrate supplement diet (CSD) for Ongole crossbred bulls in an Indonesian village fattening system. Bulls were given the current feeding system (CFS) ad libitum (T0, control) and CFS ad libitum + 1 % live weight (on approximate DM basis) of five different CSD (T1, T2, T3, T4 and T5). Treatments were: T1 (CFS + CSD mash: 25 % GLM + 25 % SBH + 50 % DCP), T2 (CFS + CSD pellet: 25 % GLM + 25 % SBH + 50 % DCP), T3 (CFS + CSD pellet: 50 % GLM + 25 % SBH + 25 % DCP), T4 (CFS + CSD pellet: 50 % GLM + 5 % SBH + 20 % DCP + 10 % PH + 15 % PKC) and T5 (CFS + CSD mash: 50 % GLM + 5 % SBH + 20 % DCP + 10 % PH + 15 % PKC). The experiment was carried out for 12 weeks and arranged in a randomized complete block design with 10 head per treatment. Animals were ranked and blocked based on pre-experiment live weight. The measured experimental variables consisted of growth performance and blood profile. Results showed that CSD supplementation significantly (P < 0.05) increased dry matter intake and average daily gain of Ongole crossbred bulls without affecting the feed to gain ratio. There were no differences in the average daily gain (ADG) between CSD treatments despite a difference in crude protein (CP) content (9 vs 13 % CP) between high and low DCP inclusion levels (25 % vs 50 %) and inverse GLM inclusion, or mash vs pelleted processing method. This suggested that the response was due primarily to increased metabolisable energy supply rather than CP supply. Daily income over feed cost (IOFC) was highest in T5 treatment (38 % higher than the control) which was formulated to provide the lowest cost of CSD ration. In conclusion, pelleting did not affect the performance of bulls, GLM and DCP could be used effectively at high levels, and a least cost ration approach was most effective in increasing the daily IOFC for smallholder farmers.

Methane emission, nitrogen and energy utilisation of beef cattle when replacing or omitting soybean meal in a forage-based diet

Replacing imported soybean meal (SBM) by domestic protein sources such as grain legumes, food industry by-products or novel resource-efficient feeds is a current research focus to enhance the sustainability of ruminant production systems. In addition, grass silage replacing maize silage can contribute to dietary crude protein (CP) supply as well and complies with the natural diet of ruminants. An experiment with 30 Limousin-sired beef bulls was performed with diets in which SBM was replaced by alternative protein sources when feeding a diet composed of, per kg dry matter (DM), 500 g grass silage, 300 g maize silage and 200 g concentrate. In the concentrate, SBM (control diet) was replaced by faba beans, pumpkin seed cake, or spirulina (Arthrospira platensis) to result on average in 226 g CP/kg concentrate dry matter (DM). A fifth group served as negative control, which received a grain-based concentrate with only 135 g CP/kg DM. Bulls were fed the experimental diets for the entire fattening period starting from an initial body weight (BW) of 164 ± 2.3 kg and 4.3 ± 0.06 months of age. At an average body weight (BW) of 275 ± 5.6 kg and 7.4 ± 0.17 months of age, each animal underwent a 9-day sampling period to determine individual N and energy intake and excretion (7 days of urine and faeces collection) as well as methane emission (2 days in respiration chambers). The diet had no effect on DM and nutrient intake. Apparent fibre digestibility was significantly affected by diet, being numerically lowest with faba beans instead of SBM. Compared to the other groups, the bulls fed no additional protein had the lowest urinary N excretion (25.1 vs. 40.3 g/bull/day; 366 vs. 460 g/kg total faecal and urinary N). Digestive and metabolic energy utilisation were comparable among diets. Methane (CH4) production adjusted to body weight differed significantly among groups, being numerically highest in bulls fed faba beans (547 vs. 513 mg CH4/kg BW/day in the other diets). These results show that none of the tested protein sources, including SBM, was of benefit when feeding a diet containing 500 g/kg DM grass silage complemented with maize silage and concentrate. Feeding such a diet seems to provide an adequate supply with metabolisable protein. Omitting the common protein supplementation therefore mitigated urinary N losses and thus likely N emissions from the manure at unchanged N and energy utilisation.

Milk production potential of whole crop faba bean silage compared with grass silage and rapeseed meal

The objective of the present study was to compare the effect of whole crop faba bean silage with grass silage as forages for lactating dairy cows. The experiment also allowed comparison of the milk production response of faba bean crude protein (CP) to that derived from a rapeseed meal supplement. Three experimental diets were used: (1) Grass silage supplemented with a cereal-based concentrate (CON), (2) 75% of grass silage replaced on dry matter (DM) basis with whole crop faba bean silage supplemented with a cereal-based concentrate (FB) and (3) Grass silage supplemented with a cereal and rapeseed meal-based concentrate (RSM) so that it was isonitrogenous with FB. The diets were fed as total mixed rations and the target proportion of concentrate in total diet DM was 400 g/kg. The experimental design was a nine times replicated 3 × 3 Latin square and 27 dairy cows were recruited into the experiment. Diet DM intake was significantly greater (P < 0.05) with FB and RSM compared with CON, which was reflected in lower (P < 0.05) milk, energy corrected milk and milk protein outputs of cows on CON than those on FB and RSM. There were no significant differences in milk and protein yields between FB and RSM but energy corrected milk and milk fat yields were greater on RSM (P < 0.05). Milk urea content was lowest in CON and highest on FB while RSM was intermediate (P < 0.05). Whole crop faba bean silage provides a viable option for feed production of dairy farms under Northern European climatic conditions with positive influence on e.g., biodiversity and flexibility in harvesting schedules. In spite of the moderate energy value of faba bean silage, it has a good feed intake potential, and when replacing grass silage in the diet, can be assumed to maintain or even increase milk yield. The higher supply of CP from FB compared to that of grass silage is however not as valuable as that originating from rapeseed meal, and decreasing nitrogen use efficiency seems inevitable irrespective of the source of additional CP content in the diet of dairy cows.

Evaluating the Protein Value of Fresh Tropical Forage Grasses and Forage Legumes Using In Vitro and Chemical Fractionation Methods.

Simple SummaryVarious methods for estimating post-ruminal crude protein supply have been developed for temperate ruminant feedstuffs. However, their adequacy (i.e., accuracy and precision) to predict the post-ruminal crude protein supply of tropical forages is still questioned. Therefore, the objectives of the present study were: (1) to assess the adequacy of the in vitro and chemical methods to predict post-ruminal crude protein supply from fresh tropical forage, and (2) to identify nutritional composition variables that can predict post-ruminal crude protein supply. The in vitro method can estimate post-ruminal protein supply in tropical forages with moderate to high but not very slow passage rates. Available regression equations developed for temperate ruminant feedstuffs were not adequate enough to predict the post-ruminal protein supply of tropical forages. Instead, equations developed in the present study appear to predict the post-ruminal protein supply of tropical forages with reasonable adequacy.The objectives of the present study were (1) to assess the adequacy of the in vitro and chemical methods to predict post-ruminal crude protein supply (PRCP) from fresh tropical forage, and (2) to identify PRCP supply predictors. Twenty-three fresh forage grasses and 15 forage legumes commonly used in domestic cattle feeding in the tropics and subtropics were incubated in the rumen of cows to determine ruminal crude protein (CP) degradation. The PRCP supply was calculated from in situ rumen-undegraded CP and in vitro organic matter digestibility (i.e., reference method), from ammonia-nitrogen release during in vitro incubation (i.e., in vitro method), and from the concentrations of chemical CP fractions (i.e., chemical method). The adequacy was evaluated using error-index and dimensionless parameters, and stepwise regression was used to select PRCP predictors. Adequacy ranged from poor to moderate (0.53 to 0.74) for the in vitro method being lower for forage legumes at a slow rumen passage rate (0.20), and even poorer (0.02 to 0.13) for the chemical method. Hence, the in vitro method can estimate PRCP supply in tropical forages with moderate to high but not with slow passage rates. Equations developed in the present study appear to predict PRCP supply with reasonable adequacy.

Dairy feed efficiency and urbanization – A system approach in the rural-urban interface of Bengaluru, India

Efficient resource use is essential for sustainable dairy production. Urbanization, however, challenges resource availability and thus the feeding strategy of dairy producers living in urbanizing environments. As an emerging megacity, Bengaluru, in Southern India, combines rapid urbanization with a high demand for dairy products. To assess the impacts of urbanization on feeding strategy and resource use efficiency of dairy producers, measured as feed efficiency (milk production divided by feed offered), 28 dairy farms, from four dairy production systems (DPS) coexisting within Bengaluru's rural-urban interface, were monitored at 6-week intervals during one year. Out of the four DPS, one was extensive and found along the whole rural-urban interface (ExtDPS), two were rural and semi-intensive (Semi-ADPS and Semi-BDPS) but differed in the genotypes of dairy cattle kept, and one was rural and intensive (IntDPS). Feed intake and quality, milk offtake and quality, were monitored at each visit. Nutritional requirements of productive dairy cattle were estimated on the basis of production data. Daily intake of dry matter was high in IntDPS, intermediate in Semi-ADPS and Semi-BDPS, and low in ExtDPS, in which dairy producers were mostly landless and did not cultivate forages but relied on market wastes and public grounds for grazing and forage collection. Feed intake in Semi-ADPS, Semi-BDPS and IntDPS resulted in mostly adequate supply or oversupply of metabolizable energy and crude protein, whereas the feeding strategy of ExtDPS lead to mostly adequately supplied to undersupplied cattle. Daily offtake of energy-corrected milk (ECM) was the lowest in one semi-intensive DPS (Semi-ADPS = 8.2 kg cow−1) but, despite a similar feeding strategy, highest in the other semi-intensive DPS (Semi-BDPS = 10.2 kg cow−1) and in IntDPS (10.9 kg cow−1; P < 0.05). Milk offtake corrected for body weight was affected by days-in-milk, daily feed intake, metabolic disorders and temperature-humidity index. Feed efficiency was highest in ExtDPS with 1.0 kg ECM kg−1 dry matter. Average feed efficiency per DPS ranged between 0.7 and 0.9 kg ECM kg−1 dry matter in the three other DPS, despite more intensive feeding strategies. By relying on easily available local resources and grazing, dairy producers in ExtDPS achieved the highest feed efficiency system-wise with minimum inputs in land and labor, while feed resources were wasted in more intensive DPS. Bengaluru's case study indicates that within an urbanizing environment, dairy producers might choose distinctly different feeding strategies that lead to differences in intensification level and resource use efficiency.

High-level dietary crude protein decreased backfat thickness and increased carcass yield score in finishing Hanwoo beef cattle (Bos taurus coreanae).

Recently, a high level of dietary crude protein (CP) has become of interest as a possible practice to improve the carcass quality of beef cattle, and its level has been increasing in the field. However, there is little scientific evidence that supports this. This study was conducted to test whether a high dietary CP level would improve growth performance, body metabolism, and carcass traits in Hanwoo beef cattle. A total of 32 Hanwoo finishing beef cattle (18 multiparous cows, six heifers, and eight steers) participated in a 12-weeks feeding trial. Two kinds of total mixed rations were prepared to contain two different CP; 156 g/kg for the control (CON) and 173 g/kg of CP for the treatment (HCP), while maintaining a similar level of metabolizable energy. The experiment was ended when more than half of the steers reached the target body weight (730 kg). Blood was collected at the end of the experiment. After harvesting, the carcass trait was evaluated at the slaughterhouse according to Korean standards. The carcass yield score and grade were also calculated based on revised criteria. Overall, dry matter intake, average daily gain, blood metabolites concentration, and the carcass traits, except for backfat thickness and the yield score, did not differ between the treatments. The HCP had lower backfat thickness than those of CON. There was no difference in the carcass yield grade, but the yield score was higher in the HCP treatment. According to the newly revised carcass grading criteria, both yield score and grade were higher in HCP than in CON. Increasing CP supply decreased the carcass’s backfat thickness without altering growth performance and body metabolism, resulting in improved yield score and grade. Therefore, feeding a high CP diet may be beneficial in the farm income, although it may also increase feed cost and nitrogen excretion to the environment.

Economic and environmental effects of revised metabolizable protein and amino acid recommendations on Canadian dairy farms

The objective of this research was to evaluate the potential economic and environmental effects of the formulation model used to balance dairy rations for metabolizable protein (MP) or 3 essential AA (EAA: His, Lys, and Met) in 3 regions of Canada with different farming systems. The Maritimes, Central Canada, and the Prairies reference dairy farms averaged 63, 71, 144 mature cows per herd and 135, 95, 255 ha of land, respectively. Using N-CyCLES, a whole-farm linear program model, dairy rations were balanced for (1) MP, based on National Research Council (NRC) requirements (MP_2001); (2) MP plus Lys and Met, based on NRC (AA_2001); (3) MP (MP_Rev); or (4) for His, Lys, and Met (AA_Rev), both based on a revised factorial approach revisiting both supply and requirements of MP and EAA. Energy was balanced to meet requirements based on NRC (2001). Assuming the requirements were met within each approach, it was considered that milk yield and composition were not affected by the type of formulation. Given the assumptions of the study, when compared with MP_2001 formulation, balancing dairy rations using the AA_Rev approach reduced calculated farm N balance by 3.8%, on average from 12.71 to 12.24 g/kg of fat- and protein-corrected milk; it also enhanced farm net income by 4.5%, from 19.00 to 19.70 $CAN/100 kg of fat- and protein-corrected milk, by reducing inclusion of protein concentrate in dairy rations. Calculated animal N efficiency was on average 4.3% higher with AA_Rev than with MP_2001 for mid-lactation cows. This gain in N efficiency would result in a reduction in N2O emission by manure, contributing to a partial decrease of total greenhouse gas emission by 1.7%, through a reduction of N excreted in manure. With the AA_2001 formulation, farm N balance was 1% higher than with MP_2001 formulation while reducing farm net income by 6.4%, due to the need to purchase rumen-protected AA, with no effect on total greenhouse gas emission. Both MP formulations lead to fairly similar outputs. The AA_Rev formulation also indicated that His might be a co-limiting AA with Met in dairy rations balanced with ingredients usually included in Canadian dairy rations. Given the assumptions of the study, balancing dairy rations for 3 EAA (His, Lys, and Met) rather than MP, has some potential positive effects on Canadian dairy farms by increasing net incomes through a reduction of crude protein supply, leading to a decreased environmental effect.

The effects of rumen nitrogen balance on intake, nutrient digestibility, chewing activity, and milk yield and composition in dairy cows vary with dietary protein sources

The objective was to study the interaction effects of rumen nitrogen balance (RNB) and dietary protein source on feed intake, apparent total-tract digestibility (ATTD), eating and ruminating activity, milk yield (MY), and milk composition in lactating dairy cows. Twenty-four lactating Holstein cows were divided in 4 groups, which were randomly assigned to the dietary treatments included in a replicated 4 × 4 Latin square experimental design that consisted of four 20-d periods, each with 12 d of adaptation to the experimental diets and 8 d of sampling. The dietary treatments followed a 2 × 2 factorial arrangement with 2 main protein sources, faba bean grain (FB) and SoyPass (SP; Beweka Kraftfutterwerk GmbH), offered at 2 dietary RNB levels: RNB0 (RNB of 0 g/kg of dry matter) and RNB- (RNB of -3.2 g/kg of dry matter; i.e., 4 treatments). The composition of concentrate mixtures was adjusted to create diets with the desired RNB levels. Each of the protein sources supplied ≥35% of the total dietary crude protein (CP). Both diets within a protein source had similar forage sources and forage to concentrate ratios and were iso-energetic, but differed in CP concentrations. The main effects of RNB, protein source, and their interactions were tested by PROC MIXED in SAS 9.4 (SAS Institute Inc.). Interaction effects were observed for daily dry matter intake and energy-corrected MY, which were lower for RNB- than RNB0 in diets containing FB (23.5 vs. 24.4 kg dry matter/d; 28.6 vs. 30.6 kg milk/d), but similar in diets containing SP (24.2 vs. 24.3 kg dry matter/d; 31.3 vs. 31.7 kg milk/d). The ATTD of NDF was lower for RNB- compared with RNB0 in the FB (44.9 vs. 49.1 g/100 g) and SP (48.5 vs. 51.9 g/100 g) diets, and greater for the SP than for FB diets. There were interaction effects for ATTD of CP and concentrations of milk urea nitrogen, which were lower for RNB- compared with RNB0 in both, FB (55 vs. 63.1 g/100 g of CP; 5.65 vs. 11.3 mg/dL milk) and SP diets (60 vs. 64.4 g/100 g of CP; 8.74 vs. 13.4 mg/dL milk). However, differences between RNB levels were greater for FB than for SP diets. Furthermore, proportions of milk fatty acids followed the same pattern as that of dietary fatty acids, but biohydrogenation appeared to be greater for RNB- than RNB0 for both protein sources and in FB than in SP diets for both RNB levels. There was an interaction effect on total number of chews per unit of NDF intake, which was greater for RNB- compared with RNB0 for both protein sources. However, the differences between RNB levels were greater in FB than in SP diets. Overall, differences in the animal responses to negative RNB between FB and SP diets suggest a need to better understand the effect of negative RNB levels with different dietary ingredients at similar utilizable CP supply.

Protein deficiency – a challenge to livestock productivity enhancement in Nepal

An assessment was made in 2019 to determine the crude protein (CP) supply situation for the livestock in Nepal. The land resources were assessed by utilizing the land use data generated by ICIMOD in 2010. The Land Resource Mapping Project (LRMP) (1986) remained the main source of data to estimate the CP supplies from these land resources (forests, shrub lands, grasslands, croplands, including weeds, and barren lands), plus kitchen wastes as animal feeds. Crop data of the Ministry of Agriculture and Livestock Development (MoALD) (2016/17) were utilized to estimate the CP supply from crop residues and milling by-products and the livestock data to estimate livestock feed requirements. The study findings revealed that there is critical shortage of CP in the livestock feeds across the eco-zones and across the provinces, with an overall deficit of 52.8%. The shortage reached about 60% in Province One and Three. The deficit in other provinces ranged from 37.6% to 52.6%. These deficits are mainly associated with the dependency of livestock production system on crop residues and low quality roughages. It is recommended that the future livestock development strategy focuses at encouraging farmers to replace the use of straws and stovers with improved forage or pasture and tree fodders. Likewise promotion of commercial silage production and development of productive partnerships with the feed millers for adequate production and supply of major imported poultry feed ingredients such as yellow maize and soybean are also important to consider.

The effects of 2-hydroxy-4-methylthio-butanoic acid supplementation on the rumen microbial population and duodenal flow of microbial nitrogen

Four multiparous, lactating Holstein cows (average DIM 169.5 ± 20.5 d), fitted with ruminal and duodenal cannulas, were used in a 4 × 4 Latin square with a 2 × 2 factorial arrangement of treatments to investigate the effects of 2-hydroxy-4-methylthio-butanoic acid (HMTBA) when fed with diets differing in metabolizable protein (MP) supply and equal levels of crude protein on milk production and composition, rumen microbial activity, duodenal protein flow, and rumen bacterial community composition in vivo and in vitro. Experimental periods were 28 d in length. Cows were housed in individual tie stalls and were randomly assigned to 4 dietary treatments: low MP or high MP, supplemented with or without 25 g of HMTBA, which was top-dressed once daily at 0930 h. No interactions were observed between HMTBA and level of dietary MP, with the exception of ruminal acetate-to-propionate ratio. Milk yield was not affected by treatment and averaged 23.8 ± 2.06 kg/d. There was a tendency for increased milk protein percent in cows receiving low MP diets, averaging 3.30 ± 0.09% and 3.21 ± 0.09% for low MP and high MP, respectively. The total-tract apparent digestibility of organic matter, neutral detergent fiber, and nitrogen were greater in cows consuming the low MP diet. Rumen pH was lower in cows consuming high MP diets as well as in those consuming HMTBA. Rumen ammonia concentrations tended to be greater in cows consuming HMTBA, and volatile fatty acid concentrations were greater in cows consuming HMTBA. Duodenal dry matter flow, nitrogen flow, and microbial nitrogen flow did not differ between treatments. The bacterial community structure of cows receiving HMTBA was not affected at the phylum level. The relative abundance of bacterial phyla in vivo differed when compared with in vitro conditions for Firmicutes, Bacteroidetes, Proteobacteria, TM7, Tenericutes, Spirochaetes, SR1, and Verrucomicrobia.

Short communication: A pilot study to describe duodenal and ileal flows of nutrients and to estimate small intestine endogenous protein losses in weaned calves

The aims of this pilot study were (1) to evaluate the effect of an ileal and duodenal cannulation surgery on body weight and dry matter intake, (2) to estimate endogenous losses of crude protein (CP) and AA in the small intestine, and (3) to describe duodenal and ileal flows of nutrients in weaned dairy calves. Three Holstein male calves were fitted at 7 wk of life with a T-cannula at the terminal ileum and another cannula at the proximal duodenum. On wk 14 of life, calves were randomly assigned to a single 3 × 3 Latin square with 10-d periods. The 3 diets were fed ad libitum and consisted of a control calf starter (CS) with conventional soybean meal (SBM) as the main source of protein (CTRL), an isonitrogenous (20% CP) CS with an enzyme-treated SBM as the main source of protein (ENZT), and a CS with low content of CP (10%) and no soy protein (LOCP). Flows and digestibilities of nutrients were compared between the soy-based high-protein diets (HICP) and LOCP, and between CTRL and ENZT. Final data were only available from 2 calves per diet (n = 2) because cannulas from 1 calf became inoperative after the first collection period. Duodenal flows of CP, total AA, nonprotein nitrogen, microbial N, and fatty acids, as well as apparent duodenal digestibility of starch, were greater for HICP than for LOCP, indicating a greater foregut microbial activity and digestion. The apparent ileal digestibility (AID) of organic matter, CP, and total AA were greater for HICP than for LOCP. Duodenal net flow of CP was greater for ENZT than for CTRL, but flow of AA was not different. On the other hand, duodenal flow of microbial N was greater, and flows of nonprotein N and starch were lower for the ENZT diet, suggesting a more efficient microbial activity in the rumen. Even though CTRL had a greater AID when compared with ENZT, the AID of CP and AA were greater for enzyme-treated SBM than for SBM. Endogenous losses in the small intestine per kilogram of duodenal dry matter flow were 47 ± 15 and 37 ± 12 g/d, and the true ileal digestibilities for the HICP diets were 86 ± 0.1 and 87 ± 0.1% for CP and AA, respectively. An optimal supply of CP and the inclusion of an enzyme-treated SBM improved the efficiency of microbial digestion and increased AA absorption. Although further research with greater biological replication is needed, our results indicate that there is potential to improve digestion and absorption of proteins through dietary strategies in young weaned calves.

Milk urea nitrogen concentration is higher in Brown Swiss than in Holstein dairy cows despite identical feeding.

Milk urea nitrogen (MUN) content is closely related to blood urea nitrogen (BUN) concentration and reflects the balance of dietary crude protein and energy supply for ruminal microbial metabolism. The present study investigated whether the higher MUN content in Brown Swiss (BSW) compared with Holstein (HOL) cows is related to milk production and feeding conditions. Therefore, we evaluated test-day records of three consecutive official milk recordings from 86 BSW and 200 HOL cows kept on the same farm under identical feeding and management conditions. In addition, the relationships between BUN and MUN assessed either by an enzymatic method or by mid-infrared spectroscopy were analysed. For the second objective, milk and blood samples (1,112 samples each) were collected in parallel from day 5 until day 150 of lactation from 141 dairy cows housed at different farms. Concentrations of MUN determined either enzymatically (MUNENZ ) or by Fourier transform infrared spectroscopy (FTIR; MUNIR ) were regressed on the BUN concentrations of the concomitantly obtained blood samples. Both MUNIR and MUNENZ were well correlated with BUN (r=.93 and .89 respectively). Concentration of MUN was higher in BSW compared with HOL independently of lactational stage or parity number (p<.0001). Protein and fat content were higher in BSW than in HOL (p<.05). Primiparous cows had lower milk yield and ECM (p<.001 for BSW, p<.0001 for HOL) than multiparous in both breeds. Multiparous BSW had a similar milk production than primiparous HOL (p=.13). In conclusion, BSW cows have higher MUN than HOL when kept under identical feeding and management conditions. The higher MUN in BSW compared with HOL cows is not related to milk production and therefore rather genetically determined.

Influence of feeding sunflower seed and meal protected against ruminal fermentation on ruminal fermentation, bacterial composition and in situ degradability in sheep

ABSTRACT The effects of treating sunflower seed (SS) and meal (SM), as well as of a mixture of both feeds (SSM; 45:55) with a solution of malic acid (1 M; 400 ml/kg feed) and heating for protection against ruminal degradation were studied. Four rumen-fistulated sheep were fed two mixed diets composed of oat hay and concentrate (40:60) and differing only in the concentrate, that contained either a mixture of untreated SS and SM (control diet) or treated SS and SM (MAH diet). A crossover design with two 24-d experimental periods was used, and each period included 10 d of diet adaptation, 9 d for in situ incubations of SS, SM and SSM, and 5 d for measuring ruminal fermentation characteristics and rumen emptying. From day 6 onwards a solution of (15NH4)2SO4 was continuously infused into the rumen of each sheep to label ruminal bacteria. Feeding the MAH diet did not affect either ruminal pH or concentrations of total volatile fatty acids and NH3-N, but decreased (p ≤ 0.01) the molar proportions of acetate and propionate and increased those of butyrate (p< 0.001). Organic matter and lipid contents of ruminal bacteria were lower whereas both N content and 15N enrichment were greater (p ≤ 0.05) in MAH-fed sheep. The in situ effective degradability (ED) of different fractions of SS, SM and SSM were calculated from the ruminal rates of particle comminution and passage, and values were corrected for microbial contamination. The MAH treatment decreased the ED of most fractions for all feeds and increased the supply of by-pass crude protein (CP) by 19.1% and 120% for SS and SM, respectively, and that of fat by 34% for SS. The MAH treatment also increased the in vitro intestinal digestibility of the by-pass CP for both SS (from 60.1% to 75.4%) and SM (from 83.2% to 91.0%). The simultaneous heating of both feeds (SSM) reinforced the protective effect of the MAH treatment and increased the by-pass CP without altering its intestinal digestibility, increasing the intestinally digested CP content by 16.8% compared with the value estimated from the results obtained for MAH-treated SS and SM incubated independently. These results indicate that the MAH treatment was effective to protect sunflower protein against rumen degradation and increased its intestinal digestibility.

Meta-analysis of the effects of prepartum dietary protein on performance of dairy cows

The objectives were to review the published literature and use meta-analytic methods to determine the effects of dietary protein fed prepartum on productive performance of dairy cows. The hypothesis was that responses to dietary protein prepartum would differ between nulliparous and parous cows, and performance would be maximized at a greater protein supply in nulliparous than in parous cows. The literature was systematically reviewed, searching randomized experiments in which the prepartum dietary content or degradability of protein was manipulated. Twenty-seven experiments including 125 treatment means and 1,801 cows were included in the meta-analysis. Of those, 8 experiments with 27 treatment means reported responses for 510 nulliparous cows. Data collected included the ingredient composition and chemical analyses of prepartum diets, parity group, and means and respective measures of variance for productive responses. Mixed model meta-analysis was conducted and statistical models investigated the effects of dietary crude protein (CP) or supply of metabolizable protein (MP) prepartum on performance. Supply of MP was predicted using the National Research Council Nutrient Requirements of Dairy Cattle (2001) model. The mean ± standard deviation and median (range) concentrations of dietary CP fed to cows prepartum were 14.4 ± 2.2 and 14.4% (8.9 to 20.9%), resulting in mean and median (range) intakes of CP prepartum of 1,720 ± 432 and 1,734 g/d (745 to 2,482 g/d). Predicted prepartum supply of MP averaged 822 ± 157 in nulliparous cows, ranging from 517 to 1,094 g/d, and 1,146 ± 316 in parous cows, ranging from 463 to 1,733 g/d. Increasing prepartum CP content or predicted supply of MP improved postpartum dry matter intake in nulliparous cows, but increasing prepartum CP content reduced prepartum dry matter intake in parous cows. Yields of milk and fat-corrected milk increased with increasing prepartum supply of MP in nulliparous but not in parous cows. Yields of fat and protein increased in nulliparous cows with increased CP content or supply of MP. Alternatively, in parous cows, yield of milk fat was not influenced by supply of MP but responded quadratically to dietary CP content and was maximized at approximately 14% CP. Dietary CP had no effect on protein yield in parous cows, but increasing the supply of MP improved protein yield only in cows from experiments with >36 kg/d of milk production, whereas MP supply had no effect on protein yield of parous cows from experiments with <28 kg/d of milk production. Performance of dairy cows was responsive to prepartum supply of MP and nulliparous benefited from diets with increased MP intake. Based on current results, production responses for nulliparous cows increased linearly up to the maximum MP intake of 1,100 g/d observed in the study, whereas for parous cows, only yield of milk protein in cows producing more than 36 kg of milk/d was influenced by supplying more than 800 g/d of MP.

Oscillating and static dietary crude protein supply. I. Impacts on intake, digestibility, performance, and nitrogen balance in young Nellore bulls.

: Effects of dietary crude protein (CP) supply on intake, digestibility, performance, and N balance were evaluated in young Nellore bulls consuming static or oscillating CP concentrations. Forty-two young bulls (initial BW of 260 ± 8.1 kg; age of 7 ± 1.0 mo) were fed ad libitum and were randomly assigned to receive one of six diets with different CP concentrations for 140 d: 105 (LO), 125 (MD), or 145 g CP /kg DM (HI), and LO to HI (LH), LO to MD (LM), or MD to HI (MH) oscillating CP at a 48-h interval for each feed. At the end of the experiment, bulls were slaughtered to evaluate carcass characteristics. Linear and quadratic effects were used to compare LO, MD, and HI, and specific contrasts were applied to compare oscillating dietary CP treatments vs. MD (125 g CP/kg DM) static treatment. Dry matter intake (DMI) was not affected (P > 0.26) by increasing or oscillating dietary CP. As dietary N concentration increased, there was a subsequent increase in apparent N compounds digestibility (P = 0.02), and no significant difference (P = 0.38) was observed between oscillating LH and MD. Daily total urinary and fecal N increased (P < 0.01) in response to increasing dietary CP. Significant differences were observed between oscillating LM and MH vs. MD, where bulls receiving the LM diet excreted less (P < 0.01; 71.21 g/d) and bulls fed MH excreted more (P < 0.01) urinary N (90.70 g/d) than those fed MD (85.52 g/d). A quadratic effect was observed (P < 0.01) for retained N as a percentage of N intake, where the bulls fed LO had greater N retention than those fed HI, 16.20% and 13.78%, respectively. Both LH and LM had greater (P < 0.01) daily retained N when compared with MD. Performance and carcass characteristics were not affected (P > 0.05) by increasing or oscillating dietary CP. Therefore, these data indicate that although there is no alteration in the performance of growing Nellore bulls fed with oscillating CP diets vs. a static level of 125 g CP/kg DM, nor static low (105 g CP/kg DM) and high (145 g CP/kg DM) levels; there may be undesirable increases in environmental N excretion when the average dietary CP content is increased. The results suggest that dietary CP concentrations of 105, 125 g/kg DM, or within this range can be indicated for finishing young Nellore bulls, since it reaches the requirements, reduces the environmental footprint related to N excretion, and may save on costs of high-priced protein feeds.