Digestible Organic Matter Intake Research Articles

401 Effect of protein and starch supplementation level on intake and digestibility by steers consuming low-quality forage: I. Bos taurus

Abstract A deficiency of ruminally available N (RAN) caused by a basal diet of low-quality forage depresses forage utilization. Supplemental protein improves forage utilization by increasing RAN, resulting in increased intake and potentially improving digestion. Addition of starch to a supplement can increase total digestible organic matter (OM) intake (TDOMI); however, too much starch decreases RAN and pH potentially decreasing forage utilization. Our objective was to determine the effect of starch supplementation on intake and digestion in Bos taurus indicus steers. Accordingly, five ruminally cannulated Brahman steers [body weight (BW) = 420 ± 55 kg) were used in a 4 × 4 Latin square to evaluate the effect of decreasing supplemental starch when consuming King Ranch Bluestem hay (3.5% CP, 73% NDF). Steers received four isonitrogenous (130 mg N/ kg BW) supplements providing increasing levels of starch (2% starch = 100% soybean meal; 20% starch = 26.3% corn, 73% soybean meal, 0.7% urea; 38% starch = 51.6% corn, 47% soybean meal, 1.4% urea; 56% starch = 78.6% corn, 19% soybean meal, 2.4% urea). Five 14-d periods were conducted, consisting of 9 d adaptation and 4 d to measure intake and digestion, and 1 d for ruminal fermentation. As designed, supplement OM intake (SOMI) increased linearly (P < 0.01) as starch level increased. Other measures of intake, including forage OM intake (FOMI), total OM intake (TOMI), and total neutral detergent fiber intake (TNDFI) decreased in a cubic manner in response to increasing starch (P ≤ 0.04). Forage OMI also responded with a cubic decrease (72.2, 68.9, and 69.5 g/kg BW0.75) when the protein supplement contained 2, 20, and 38% starch, respectively, but decreased to 61.2 g/kg BW0.75 when the 56% starch supplement was provided. Similarly, TOMI decreased 5.3% when starch inclusion increased from 38 to 56%. Total tract OM digestion and NDF digestion were not significantly affected (P ≥ 0.86) by starch level in the supplement; therefore, despite TOMI and TNDFI decreasing, there was no effect on total digestible OM intake and (TDOMI) and total digestible NDF intake (TDNDFI). In conclusion, providing supplemental starch over 38% decreased forage utilization. Decreases in FOMI with starch inclusion may be attributed to competition for RAN between fiber fermenting and starch fermenting bacteria.

Mealworm larvae and black soldier fly larvae as novel protein supplements for cattle consuming low-quality forage.

The global population is projected to increase, indicating that there will be greater demand for animal protein to meet the associated food needs. This demand will place additional pressure on livestock systems to increase output while also minimizing natural resource inputs. Insect protein has emerged as a potential alternative to conventional protein feeds, such as soybean meal. Mealworm larvae (MWL; Tenebrio molitor) have been studied in poultry and swine as an alternative protein source; however, there is no research currently evaluating MWL for cattle. Black soldier fly larvae (BSFL; Hermetia illucens) have also received attention for their potential use in livestock feed due to their scalability and nutritional value, but research in cattle is limited. The objective of this study was to evaluate the effects of whole-dried MWL and defatted BSFL as protein supplements for cattle consuming forage. Five ruminally cannulated steers were utilized in a 5 × 5 Latin square experiment to determine how MWL and BSFL supplementations affect forage utilization. Steers consuming ad libitum low-quality forage (76.5% neutral detergent fiber [NDF], 4.2% crude protein) were provided one of the five treatments each period: 1) control with no supplement (CON), 2) soybean meal (CONV), 3) BSFL, 4) MWL, or 5) 50/50 by-weight blend of BSFL and MWL (MIX). All treatments were provided at 100 mg N/kg BW and periods included 8 d for treatment adaptation, 5 d for intake and digestion, and 1 d for ruminal fermentation measures. Protein supplementation stimulated forage organic matter intake (FOMI; P ≤ 0.01) relative to CON (3.28 kg/d). There was a significant difference in FOMI (P ≤ 0.01) between BSFL (4.30 kg/d) and CONV (4.71 kg/d), but not between CONV and MWL (P = 0.06, 4.43 kg/d). Total digestible OM intake (TDOMI) was also stimulated by the provision of protein (P ≤ 0.01), from 1.94 kg/d for CON to an average of 3.24 kg/d across protein supplements. Organic matter digestibility (OMD) and NDF digestibility (NDFD) were not affected by treatment (P ≥ 0.37), for an average OMD of 66.5% and NDFD of 62.7%. There was also no treatment effect on ruminal volatile fatty acid (P = 0.96) or ammonia-N (P = 0.22) concentrations. These data indicate that MWL may stimulate forage utilization by beef cattle to a greater extent than BSFL, but both are viable protein supplements.

91 Mealworm and black soldier fly larvae as protein supplements for beef steers consuming forage

Abstract The global population is projected to increase, indicating there will be greater demand for animal protein to meet the associated food needs. This demand will place additional pressure on livestock systems to increase output while also minimizing natural resource inputs. Insect protein has emerged as a potential environmentally sustainable alternative to conventional protein feeds, such as soybean meal. Further, insect protein does not compete in the human food market as the products of conventional oil crops often do. Mealworm larvae (MWL) has been studied in poultry and swine as an alternative protein feed; however, there is not currently research evaluating MWL for cattle. Black soldier fly larvae (BSFL) has also received attention for its potential use in livestock feed due to its scalability and nutritional value, but research in cattle is limited. The objective of this study was to evaluate the effects of whole dried MWL and defatted BSFL as protein supplements for cattle consuming forage. These procedures were approved by IACUC at Texas State University (#7726). Five ruminally cannulated steers were utilized in a 5×5 Latin square experiment to determine how MWL and BSFL supplementation affect forage utilization. Steers consuming low-quality forage (4.2% crude protein) were provided one of five treatments each period: 1) control with no supplement (CON), 2) soybean meal (CONV), 3) BSFL, 4) MWL, and a 5) 50% BSFL and 50% MWL by-weight (MIX). Supplements were provided at 100 mg N/kg BW. Periods included 8-d for treatment adaptation, 5-d for intake and digestion measurements, and 1-d for ruminal fermentation measures. Dry matter (DM), organic matter (OM), CP, neutral detergent fiber (NDF), and acid detergent fiber (ADF) were determined for diet, ort, and feces. Protein supplementation stimulated forage OM intake (P ≤ 0.01) relative to CON. There was a significant difference in FOMI (P ≤ 0.01) between BSFL and CONV. Steers receiving CONV treatment consumed 4.71 kg FOMI/d, which was significantly greater (P ≤ 0.01) than those receiving BSFL (4.30 kg/d). There were not differences in FOMI between other treatment groups. Total digestible OM intake (TDOMI) was stimulated by protein supplementation (P ≤ 0.01) from 1.94 kg/d for CON to an average of 3.24 kg/d across protein supplements. Organic matter digestibility (OMD) and neutral detergent fiber digestibility (NDFD) were not affected by treatment (P ≥ 0.37), for an average OMD of 66.5% and NDFD of 62.7%. There was also not a treatment effect (P = 0.96) on total volatile fatty acid (VFA) concentrations, although there were some shifts in molar proportions of individual VFAs across treatments. These data indicate that MWL may be more efficacious than BSFL in stimulating forage utilization in beef cattle, but both are viable protein supplements.

Acceptance and forage utilization responses of steers consuming low-quality forage and supplemented black soldier fly larvae as a novel feed.

As the insect-rearing industry scales in the United States and other developed nations, it has the potential to create multiple product streams (e.g., oil and protein-rich biomass) for existing markets. Black soldier fly larvae (BSFL; Hermetia illucens) has been identified as a potential livestock feed because it is not expected to compete in the human food sector and its production has a lesser environmental footprint than that of conventional feeds. Existing research on BSFL as feed focuses on full-fat BSFL for poultry and aquaculture. Therefore, the objective of our experiment was to evaluate the viability of defatted BSFL as an alternative protein source for beef cattle consuming forage. Procedures were approved by Texas State University IACUC (#7726). Two experiments were conducted using ruminally cannulated beef steers fed low-quality forage in 5 × 5 Latin squares. Experiment 1 assessed consumption of BSFL as a protein supplement and included five 5-d periods with 3-d for washout and 2-d for measurement of supplement intake and preference. There were five treatments delivered in addition to the basal forage: 100% soybean meal (SBM); 75% SBM/25% BSFL; 50% SBM/50% BSFL; 25% SBM/75% BSFL; and 100% BSFL. Supplement and forage intake did not differ between treatments (P ≥ 0.45) nor was there a treatment × day interaction (P ≥ 0.45). Experiment 2 evaluated the effect of BSFL supplementation on forage (5.3% crude protein) intake and digestion and included five 14-d periods with 8-d for treatment adaptation, 5-d for measurement of intake and digestion, and 1-d for determination of ruminal fermentation. There were four treatments of supplemental BSFL provided at graded N levels: 0, 50, 100, or 150mg N/kg BW and one level of SBM at 100mg N/kg BW. Increasing provision of BSFL linearly increased forage organic matter (OM) intake (P = 0.04), total OM intake (P < 0.01), total digestible OM intake (P < 0.01), dry matter digestibility (P = 0.01), and OM digestibility (P = 0.02). There were no significant differences (P ≥ 0.17) in intake or digestibility between levels of BSFL and SBM. Ultimately, defatted BSFL has potential to replace conventional feeds as a protein supplement without sacrificing forage utilization.

Effect of pregnancy and feeding level on voluntary intake, digestion, and microbial nitrogen synthesis in Zebu beef cows.

The objective of this research was to evaluate how pregnancy and feeding regimens affect the feed intake, digestibility, and efficiency of microbial nitrogen (N) synthesis in beef cows. Forty-four multiparous Nellore cows, comprising 32 gestating and 12 non-gestating cows, with an average weight of 451 ± 10kg, were assigned to either a HIGH (ad libitum) or LOW (limited feeding at 1.2 times maintenance based on the NRC) feeding regimen during the gestational period. The dry matter intake (DMI) in kg/d was significantly greater (P < 0.01) in HIGH-fed cows. The DMI reduced (P < 0.05) in proportion to the shrunk body weight (SBW) as days of pregnancy (DOP) increased. The interaction between feeding level and DOP was significant (P < 0.05) for the digestibility of dry matter (DM), organic matter (OM), N compounds, ether extract (EE), ash- and protein-free neutral detergent fiber (NDFap), gross energy (GE), and total digestible nutrients (TDN). Except for DM and TDN digestibility, there was a reduced nutrient digestibility as gestation progressed in HIGH-fed cows. In contrast, digestibility increased as a function of DOP in LOW-fed cows. Microbial N synthesis (g/day) was significantly higher in HIGH-fed cows (P < 0.001) compared to LOW-fed cows. The efficiency of microbial N production per g of N intake and kg of digestible OM intake was (P = 0.021) and tended (P = 0.051) to be greater in LOW-fed cows compared to HIGH-fed cows. In summary, HIGH-fed Nellore cows reduce feed intake and digestibility with advancing gestation, affecting feed utilization. In addition, LOW-fed cows, showed higher microbial protein synthesis efficiency, potentially making them more nutrient-efficient under challenging nutritional conditions.

Intake, digestibility, rumen fermentation and nitrogen balance in sheep offered alfalfa silage with different proportions of the tannin-rich legume sericea lespedeza

Dietary manipulations to include tannins can change the proportion and amounts of nitrogen (N) excreted in the urine and feces as well as improve nitrogen use efficiency by ruminants. This study was conducted to investigate the effects of adding different proportions of sericea lespedeza (Lespedeza cuneate) hay (SL) containing tannins (16.8% total condensed tannins; CT) to alfalfa (Medicago sativa) silage. Alfalfa silage was either offered alone (0 g/kg; CONT) or mixed with chopped SL to provide 90 (LOW), 180 (MED), or 270 g/kg SL (HIGH) or 15, 30, or 45 g CT/kg on a dry matter (DM) basis. These diets were offered randomly for ad libitum consumption to 16 Dorper ewe lambs (42.1 ± 1.15 kg BW; Period 1; 41.7 ± 1.12 kg BW; Period 2) in a randomized complete block design experiment where each treatment was offered to four lambs during each of two periods. The same 16 lambs were used in both periods, resulting in eight total observations/treatment. Each period consisted of a 14-d dietary adaptation period followed by 5 d of total fecal and urine collection. Data were analyzed using PROC MIXED of SAS. Dry matter (DM), organic matter (OM), neutral detergent fiber (aNDF) and acid detergent fiber (ADF) digestibility as well as digestible DM and OM intake (g/day or g/kg BW) decreased linearly (P < 0.05) with increasing SL in the diet. Ruminal acetate and butyrate molar proportions increased quadratically (P = 0.01), whereas ruminal isobutyrate and isovalerate decreased linearly (P = 0.02) with increasing SL in the diet. Apparent N absorption (g/kg N intake) decreased linearly (P < 0.05) with increasing SL in the diet. Urinary N excretions (g/kg N intake) tended (P = 0.10) to respond quadratically while fecal N (g/kg N intake) increased linearly (P < 0.01) with increasing SL proportion in the diet. In this study, supplementation with sericea lespedeza as a tannin source to alfalfa silage decreased forage digestibility without affecting feed intake, and significantly increased N excreted in feces and tended to decrease urine N excretion without affecting N balance. Therefore, feeding tannins in diet can alter N excretion route from urine to feces but may not improve N-use efficiency by the animal.

Utilising locally based energy supplements in leucaena and corn stover diets to increase the average daily gain of male Bali cattle and the income of smallholder farmers

Context Supplementing a leucaena-based diet with locally available energy sources is an important strategy to extend the use of leucaena, increase liveweight (LW) gain of Bali cattle and increase profit for the smallholder. Aims This study was conducted to evaluate the effect of various local energy supplements in leucaena-based diets on the LW gain of Bali cattle and income-over-feed costs (IOFC). Methods Forty male Bali cattle were divided into five treatment groups (n = 8) and each was fed one of the following diets: (A) control diet, including leucaena ad libitum, with corn stover at 0.5% DM LW and mineral mix, (B) control + cassava meal at 1.0% DM LW, (C) control + cassava peel at 1.0% DM LW, (D) control + cassava peel and corn grain mix at 1.0% DM LW or (E) control + commercial feed at 1.0% DM LW. The experiment was run for 140 days, which included a 20-day adaptation period. Parameters measured included intake, digestibility, imbibed-water intake, LW gain, rumen and faecal parameters, feed conversion and IOFC. Key results Supplementation of local energy sources in combination with leucaena and corn stover diets increased LW gain of male Bali cattle above that of the control diet (P &lt; 0.05). The bulls receiving the cassava peel and corn mix supplement had the highest LW gain (0.57 ± 0.09 kg/day), which was associated with an increase in digestible organic-matter intake (DOMI). There were no treatment differences (P &gt; 0.05) in the rumen parameters (rumen fluid pH, rumen ammonia-N concentration and volatile fatty acids) and all parameters were optimum for rumen digestion. Conclusions The addition of local energy supplements supplied at 1% of LW improved growth rate and extended the use of a limited amount of leucaena and provided a higher IOFC. Implications Replacing approximately 40% of leucaena with energy sources can have three benefits, including an increase in LW gain, an increased capacity of farmers to feed more cattle per hectare and an increased income per cattle being fattened. This can increase the production scale and subsequent farmer income, provided that the energy sources are available at affordable prices and obtainable.

PSXIII-21 Effects of Bacterial Direct-Fed Microbial Mixtures on Beef Cattle Feeding Behavior

Abstract The effects of bacterial direct-fed microbial (DFM) mixtures on beef cattle feeding behavior were evaluated. Six ruminally cannulated crossbred Angus steers (BW = 520 ± 30 kg) were used in a replicated 3 × 3 Latin Square design. Steers were offered a steam-flaked corn-based finishing diet to ad libitum during three, 28 d periods (21-d adaptation and 7-d collection). Treatments assigned were: 1) Control (no DFM, lactose carrier only); 2) Treat-A [L. animalis, P. freudenreichii; B. subtilis; and B. licheniformis, at 1:1:1:3 ratio, respectively; totaling 6 × 109 CFU (50mg)/animal-daily minimum (Chr.Hansen]; and 3) Treat-B, the same DFM combination, but with doses at 1:1:3:1 ratio. Bacterial counts were approximately 30% greater than the minimum expected. The DFM diluted mixtures and carrier (Control) were pre-weighed and stored at -20°C until incorporated into the diet (2 g· animal-1· /day-1) 10 min prior to feeding. For mixing, approximately 1 kg (as is) of the diet being offered was removed from the individual recipient, DFM was mixed by hand, and the mixture was incorporated into the feed allocated for the day. The feeding behavior assessment consisted of a 24 h continuous visual observation (every 5 min) performed by trained personnel. Animals were assessed on d 26 of each period (no other management other than cleaning of the stall), while time spent eating, ruminating, resting, active, and drinking were taken. Time spent chewing was accounted for by adding time spent eating and ruminating. In addition, records allowed the count of the number of meals taken, as well as the time spent on each meal. Data were analyzed using the GLIMMIX procedure of SAS, with animal considered as the experimental unit, the fixed effects of treatment, and random effect of square, period, and animal (square). F-test protected pre-planned orthogonal contrasts was used to compare Control vs. Treat-A and Control vs. Treat-B. Meal number (16/d) and length (8 min/meal) were not affected by treatments (P ≥ 0.54). Main feeding behavior variables consisting of rumination (198 min/d), eating (117 min/d), chewing (315 min/d), drinking (22 min/d), resting (929 min/d), and active (174 min/d) were not affected (P ≥ 0.24) by treatments. A tendency was observed (P = 0.08) where animals offered the Treat-B spent numerically less time ruminating per unit of digestible DM and OM intake compared with Control (13.5 vs. 15.5, and 13.7 vs 15.6 min/kg, respectively). Other behaviors measured in min/kg of DM, NDF, and ADF intake were not affected (P ≥ 0.17) by treatments [rumination (11.5, 60.2, and 181), eating (6.5, 34.4, and 104), chewing (18, 94.6, and 285), and drinking (1.2, 6.6, and 19.8) min/kg, respectively]. The bacterial DFM mixtures offered appear not to directly affect the feeding behavior of beef cattle consuming a steam-flaked corn-based finishing diet.

363 Effect of Protein and Starch Supplementation Level on Intake and Digestibility By Steers Consuming Low-Quality Forage: I. Bos Taurus Taurus

Abstract A deficiency of ruminally available N (RAN) caused by a basal diet of low-quality forage depresses forage utilization. Supplemental protein improves forage utilization by increasing RAN, resulting in increased intake and potentially improving digestion. Addition of starch to a supplement can increase total digestible OM intake (TDOMI); however, too much starch decreases RAN creating competition between fiber and starch fermenting bacteria potentially decreasing forage utilization. Our objective was to determine the effect of starch supplementation on intake and digestion in Bos taurus taurus steers. Accordingly, five ruminally cannulated Angus steers (BW 375 ± 45 kg) were used in a 4 × 4 Latin square to evaluate the effect of decreasing supplemental starch when consuming King Ranch Bluestem hay (3.5% CP, 73% NDF). Steers received four isonitrogenous (130 mg N/ kg BW) supplements providing increasing levels of starch (2% starch = 100% soybean meal; 20% starch = 26.3% corn, 73% soybean meal, 0.7% urea; 38% starch = 51.6% corn, 47% soybean meal, 1.4% urea; 56% starch = 78.6% corn, 19% soybean meal, 2.4% urea). Five 14-d periods were conducted, consisting of 9 d adaptation and 4 d to measure intake and digestion, and 1 d for ruminal fermentation. As designed, supplement OM intake (SOMI) increased linearly (P &amp;lt; 0.01) as starch level increased. Forage OM intake (FOMI) decreased linearly with increasing starch (P &amp;lt; 0.01). Increases in SOMI and decreases in FOMI combined to result in no significant (P ≥ 0.14) differences in total OMI (TOMI) between starch levels. Total digestible OMI (TDOMI) responded quadratically (P = 0.05) to increasing starch and was 45.8, 49.4, 48.4 and 41.9 g TDOMI/kg BW0.75 for 2, 20, 38, and 56% starch, respectfully. Total DOMI was 18% greater when steers were provided 20% starch supplement compared with 56% starch. Similarly, total digestible NDF intake responded quadratically (P = 0.05) and was maximized with 20% starch. Total tract OM digestion and NDF digestion were not significantly affected (P ≥ 0.15) by starch level in the supplement. In conclusion, providing supplemental starch over 20% decrease forage utilization. Decreases in FOMI with starch inclusion may be attributed to competition for RAN between fiber fermenting and starch fermenting bacteria.

Studi Kecernaan dan Konsumsi Pakan pada Kambing Peranak Etawah Jantan Muda yang diberi Pakan Hijauan Mengandung Tannin Kondensasi

This study aims to determine the effectiveness of using various levels of forage sengon leaves (Albizia falcataria) as a source of condensed tannin on dry matter intake (DMI), organic matter intake (OMI), digestible dry matter intake (DDMI), digestible organic matter intake (DOMI), dry matter digestibility (DMD), and organic matter digestibility (OMD). This study used sixteen young male ettawa cross-breed goats aged 8–12 months with an average body weight range of 19±1.8 kg. The study was arranged in a randomized block design (RBD) with four treatments and four bodyweight groups as replicates. Diet treatments consisted of R0: 60% Brachiaria mutica (BM) + 0% A. falcataria (AF) Leaf + 40% Concentrate (CON), R1: 50% BM + 10% AF Leaf + 40% Concentrate, R2: 40% BM + 20% AF Leaf + 40% CON, and R3: 30% BM + 30% AF Leaf + 40% CON. The results showed that the use of sengon leaves as a source of condensed tannin in diets significantly (P 0.05) reduced DMI, OMI, DDMI, and DOMI but did not significantly (P &gt; 0.05) affect DMD and OMD values. This study concluded that AF leaf as a forage source containing condensed tannin made up as much as 30%, or equivalently, 50%, of the forage in the diet of young male ettawa cross-breed goats without having any effect on diet intake or digestibility.

Does Replacing Maize with Barley Affect the Animal Performance and Rumen Fermentation, including Methane Production, of Beef Cattle Fed High-Concentrate Diets On-Farm?

Ruminants fed high-concentrate diets produce less enteric methane than those fed high-forage diets, but not all grains are equally effective in reducing methane production. This study aimed to examine, in farm conditions, the effects of a partial substitution of maize with barley on animal performance and rumen fermentation, including methane production, of intensively reared beef calves (ca. 0.9:0.1 concentrate to forage ratio). Ninety-six beef calves were fed a concentrate with 45.5% maize and 15% barley (n = 48; M) or a concentrate with 15.5% maize and 45% barley (n = 48; B). Both the concentrate and barley straw were offered ad libitum. The type of concentrate did not have a significant effect (p > 0.05) on final live weight, average daily gain, carcass dressing percentage or intake of concentrate and straw. Dry matter and organic matter digestibility were higher (p < 0.05) for the M (75.4% and 76.6%) than for the B (71.0% and 73.1%) treatment, but with no effect on digestible organic matter intake. In general, the majority cereal in the concentrate did not affect rumen fermentation, including methane production, or the degradability of dry matter and starch. A partial substitution of maize with barley in the concentrate offered to beef calves does not seem a promising strategy to decrease the emissions of enteric methane on-farm.

83 Effect of a Saccharomyces cerevisiae fermentation product on intake and digestion in young horses undergoing exercise training

Young growing horses subjected to exercise have greater dietary requirements than horses at maintenance necessitating the delivery of a more nutrient dense diet. Inclusion of a grain concentrate in the total daily ration achieves this goal but also may put the young horse at risk of digestive disorders and reduced forage utilization. As such, the objective of this study was to determine if a dietary S. cerevisiae fermentation product (SCFP; TruEquine C, Diamond V) could influence nutrient utilization in young horses being introduced to grain concentrate feed and if the response was dose dependent. Thirty Quarter horse yearlings (561 ± 15.8 d of age and 371 ± 24.4 kg BW) were adapted to a 14% CP grain concentrate feed (Nutrena SafeChoice Original formulated without microbial ingredients), fed at 1% of BW as fed to meet or slightly exceed nutrient requirements for yearling horses undergoing light to moderate work and allowed ad-libitum access to Coastal bermudagrass (Cynodon dactylon) hay (67.8% NDF) and fresh water. Horses were stratified by age, BW, and sex and randomly assigned to one of 3 levels of SCFP: 0, 46, or 92 mg/kg BW divided evenly and top-dressed onto the grain concentrate meal at 12 h intervals. After 14 d of adaptation, intake and total fecal production were measured overa 4-d period. Horses were housed in individual 3.7 × 3.7 m stalls and allowed 1 h of exercise in individual 3.7 × 7.4 m runs daily during the collection period. All statistical analyses were performed in SAS 9.4 using PROC MIXED with the model containing treatment and horse included as the random variable. There was no significant treatment difference for any measure of intake (P ≥ 0.33); forage DM intake averaged 6.14 kg/d, total DM intake averaged 9.60 kg/d, and total digestible organic matter intake averaged 4.97 kg/d. There was a tendency for improved DM digestibility (P = 0.09) with supplementation (56.3 and 56.8% for 46 and 92 mg/kg BW, respectively) compared with no supplementation (54.2%). Supplementation of SCFP resulted in no significant differences (P ≥ 0.15) in organic matter (OM) or NDF digestibility. There were no differences in any indicator of nutrient digestibility between the low and high level of SCFP supplementation. An observed tendency for improved DM digestibility with SCFP supplementation suggests further research is warranted.

Methane emission, nutrient digestibility, and rumen microbiota in Holstein heifers fed 14 different grass or clover silages as the sole feed

This experiment investigated the variation in enteric methane production and associated gas exchange parameters, nutrient digestibility, rumen fermentation, and rumen microbiome when a range of silages based on different forage types (grass or clover), and different species within the 2 types, were fed as the sole feed to heifers. Three grass species (perennial ryegrass, festulolium, and tall fescue) and 2 clover species (red clover and white clover) were included. Perennial ryegrass was harvested at 2 maturity stages in the primary growth, white clover was harvested once in the primary growth, and 4 cuts of festulolium and tall fescue and 3 cuts of red clover were harvested during the growing season, giving 14 different silage batches in total. Sixteen Holstein heifers 16 to 21 mo old and 2 to 5 mo in pregnancy were fed the silages ad libitum as the sole feed in an incomplete crossover design. Each silage was fed to 4 heifers, except for the 2 perennial ryegrass silages, which were fed to 8 heifers; in total 64 observations. The CH4 production was measured for 3 d in respiration chambers. Heifers fed clover silages had higher dry matter intake (DMI) compared with heifers fed grass silages, and heifers fed tall fescue silages had the numerically the lowest DMI. Compared with grass silages, feeding clover silages led to higher crude protein digestibility but lower neutral detergent fiber (NDF) digestibility. Rumen pH was higher in heifers fed clover silages compared with those fed grass silages. Based on composition analysis, the rumen microbiota of the heifers clustered clearly according to forage type and species. More specifically, 7 of the 34 dominating rumen bacterial genus-level groups showed higher relative abundances for the clover silages, whereas 7 genus-level groups showed higher abundances for the grass silages. Methane yield was higher for heifers fed grass silages than for those fed clover silages when methane production was related to dry matter and digestible organic matter intake, whereas the opposite was seen when related to NDF digestion. The gross energy lost as methane (CH4 conversion factor, %) reduced from 7.5% to 6.7%, equivalent to an 11% reduction. The present study gives the outlines for choosing the optimal forage type and forage species with respect to nutrient digestibility and enteric methane emission in ruminants.

PSII-3 Effect of Protein Supplementation Level and Degradability on Forage Utilization by Steers Consuming Low-Quality Forage: II. Bos taurus indicus

Abstract A deficiency of ruminally available N (RAN) caused by a basal diet of low-quality forage may depress forage utilization. Supplemental protein improves utilization by addressing the RAN therefore increasing intake and potentially improving digestibility. The objective of this study was to determine the effect of ruminal degradability and level of protein supplementation on forage utilization by Bos taurus indicus steers. Accordingly, five ruminally cannulated Brahman steers (BW 369 ± 51 kg) were used in a 5 × 5 Latin square to evaluate the interaction between level and degradability of protein supplementation when consuming a basal diet of King Ranch Bluestem hay (3.5% CP, 71.0% NDF). Treatments were arranged as a 2 × 2 factorial with steers receiving protein supplements (43% CP) having two levels of protein degradability (35 or 70% RDP) fed at two levels of supplementation, 1.26 or 2.53 g/kg BW (LOW and HIGH). A control treatment providing no supplemental protein was also included (CON). Five 14-d periods were conducted, consisting of 9 d adaptation, 4 d to measure intake and digestion, and 1 d for ruminal fermentation. No degradability × level interactions were observed for any measures of intake or digestion (P &amp;gt; 0.10). Protein supplementation linearly increased (P &amp;lt; 0.01) total digestible OM intake (TDOMI), NDF intake (P = 0.01), and total digestible NDF intake (DNDFI; P &amp;lt; 0.03). Total digestible OMI was greater in steers receiving 70% RDP than the 35% RDP (P = 0.08). This response resulted from the linear increase in FOMI with 75% RDP (P = 0.03), that was not observed with 35% RDP. Despite differences in FOMI, TDOMI increased linearly (P ≤ 0.03) for both 35 and 70% RDP, partially the result of providing a highly digestible supplement. Forage OMI differences also resulted in NDFI being greater for 70% RDP than 35% RDP (P = 0.06) and DNDFI increasing linearly with the addition of both supplements (P ≤ 0.03). Organic matter digestibility (OMD) increased linearly with supplementation as a result of supplement provision. In contrast to observations previously reported in Bos taurus steers, provision of 35% RDP supplement did not improve FOMI. Supplementation with 70% RDP improved FOMI 19 and 20% compared to the basal diet at LOW and HIGH levels, respectively. A portion of this relatively modest response to protein supplementation could be attributed to greater intake in the unsupplemented controls.

Fibrous coproducts of corn and citrus as forage and concentrate sources for dairy cows.

This study evaluated the effect on dairy cows of the partial replacement of whole plant corn silage (WPCS) with corn ear fibrous coproduct (CEFC) in diets with concentrate coproducts from citrus and corn on dry matter intake (DMI), lactation performance, digestibility, and chewing behavior. Holstein dairy cows (n = 20) in 5, 4 × 4 Latin squares (21-d periods) were fed a combination of strategies for feeding fibrous coproducts in a 2 × 2 factorial arrangement of the following treatments: (1) forage feeds: the partial replacement of WPCS (CS) with CEFC (CO), and (2) concentrate feeds: the partial replacement of wet corn gluten feed (GF) with a blend of pelleted citrus and corn distillers dried grains (CD) to have isonitrogenous diets. The concentrations of physically effective neutral detergent fiber (NDF; peNDF>8) were (% of dry matter): 21.8% for CS, 19.2% for CO, 20.7% for GF, and 20.2% for CD. Cows fed diet CS-CD had the highest yield of energy-corrected milk (30.0 kg/d) relative to the other diets (28.4 kg/d). Milk fat concentration was reduced on CO relative to CS. Cows fed the CO diets had higher DMI (21.2 vs. 20.2 kg/d) and digestible organic matter intake and tended to have a lower ratio of energy-corrected milk to DMI than cows fed CS. Diets CO reduced the daily intake of peNDF>8 and the intake as percent of body weight of peNDF>8, forage NDF, and total NDF relative to CS. Cows fed CO had greater meal frequency and lower daily meal time, meal duration, meal size, and duration of the largest meal than cows fed CS. The CO diet reduced rumination and total chewing in minutes per day and minutes per kilogram of DMI. When expressed per unit of peNDF>8 intake, rumination and total chewing were not affected by forage source. The total-tract starch digestibility coefficient was lower for cows fed CO than CS, but the intake of digestible starch was higher on CO than CS. Cows fed GF had reduced milk yield (29.6 vs. 30.8 kg/d), tended to have reduced DMI (20.4 vs. 21.0 kg/d), and had reduced digestible organic matter intake than cows fed CD. Feed efficiency was not affected by source of concentrate. The type of concentrate did not affect the intake of forage NDF and peNDF>8, but cows fed GF had higher intake of total NDF as percent of body weight than cows fed CD. The GF increased meal frequency and reduced meal size and largest meal duration and size. Cows fed GF had higher rumination and total chewing than cows fed CD (min/d, min/kg of DMI, and min/kg peNDF>8). Starch digestibility was higher and the intake of digestible starch tended to be higher on cows fed GF than CD. Plasma urea-N was higher, milk urea-N tended to be higher, and N utilization efficiency tended to be lower on cows fed GF than CD. Ruminal microbial yield was not affected by any treatment. All strategies evaluated were nutritionally viable and CEFC was a feasible partial replacement for WPCS.

Intake, digestibility, and nitrogen balance by sheep offered ensiled tall fescue, meadow fescue or orchardgrass that was fertilized with dairy slurry or urea

Silage intake and utilization by ruminants can be affected by several factors including forage type and fertilization. The objective of this study was to evaluate intake, digestion, and N balance by sheep offered three different ensiled grasses following fertilization with either urea (C) or dairy slurry (S). Plots of meadow fescue (MF), tall fescue (TF) or orchardgrass (OG) were fertilized with urea (52 kg N/ha; MFC, TFC and OGC) or slurry (71,150 L/ha; MFS, TFS, and OGS) on 2 July 2018 following an initial harvest on 29 June 2018. A second harvest was baled 6 August at approximately 57 % moisture and wrapped in plastic. Eighteen lambs (59 ± 1.5 kg) were allocated randomly to one of the 6 treatment combinations to provide 3 lambs per treatment within each of 3 periods for a total of 9 replications per treatment. Each period consisted of a 10-d adaptation and 7-d total fecal and urine collection. Data were analyzed as a 2 × 3 factorial arrangement using PROC MIXED of SAS. Post-ensiled crude protein (CP) concentrations were greatest from MFS and lowest from OGS (P < 0.05), and aNDF, ADF and lignin were greater (P < 0.05) from OG vs TF and MF, regardless of fertilization. Lactic acid concentrations (g/kg DM) in baled silages were greatest from TFC and lowest from MFC and OGS (P < 0.05). Dry matter (DM) and organic matter (OM) intakes (g/kg BW and BW0.75), digestibility and digestible DM and OM intakes (g/kg BW and BW0.75) were greater (P < 0.05) from MF than from TF and OG across fertilization type and digestible OM intake was greater (P < 0.05) from C vs. S across forages. Digestibility of NDF (g/kg NDF) was greater (P < 0.05) from MF and OG vs. TF across fertilization treatments. Nitrogen retention (g/kg N intake) tended (P = 0.08) to be greater from MF vs. OG and urine N (g/kg N intake and g/kg N excreted) was greater from TF and OG compared with MF across fertilization treatments. Therefore, meadow fescue has the potential to provide a higher-quality forage that will increase intake and digestibility over more conventional orchardgrass and tall fescue. Fertilization with dairy slurry affected certain forage chemical components and reduced organic matter intake but did not impact digestibility when applied 35 d prior to a subsequent harvest.

61. Estimation of digestible organic matter intake through purine derivatives from sheep fed warm-season forages

61. Estimation of digestible organic matter intake through purine derivatives from sheep fed warm-season forages

Heritability and genetic gain of digestible organic matter intake of barley straw genotypes by sheep, using repeatable in situ- and laboratory-based indicator traits

AbstractThe voluntary digestible organic matter intake (DOMI) of mature barley crops (Hordeum spp.) for sheep depends largely on straw quality. Direct measurement of DOMI is laborious; consequently, the research reported here evaluated indicator traits for improving barley straw DOMI by crop breeding. It hypothesized that some indicator traits for straw quality are heritable, facilitate genetic gain in DOMI, and reveal straw properties that constrain genetic gain. In 4 years, 32 genotypes of barley were grown at ICARDA, northern Syria, with no fertilizer in one year and supplementary irrigation in another. Indicator traits for predicting DOMI included in situ straw dry matter losses (DML) at nine incubation times (0–120 h), four parameters of the DML curve, seven laboratory tests, grain yield and straw yield. Heritability (h2) was highest for traits associated with indigestible cell wall constituents, including potential DML (h2 = 0.61), DML at 48–120 h of incubation (h2 = 0.48–0.58), and acid detergent fibre (ADF) (h2 = 0.41). Heritability was lower for DOMI itself (h2 = 0.24), neutral detergent fibre (NDF) (h2 = 0.20), and total Kjeldahl nitrogen (h2 = 0.17), and was lowest for DML at 6–18 h (h2 = 0.08–0.09) and the in situ parameters Lag and relative loss rate of slowly degradable DM (h2 ≤ 0.03). Correlations between indicator traits and DOMI tended to increase with heritability. Grain and straw yields were not correlated with DOMI; of these, only grain yield was heritable. In conclusion, genetic gain in barley straw nutritive value can be achieved by crop breeding under diverse growing conditions, using indicator traits associated with indigestible cell wall constituents.

3-Nitrooxypropanol substantially decreased enteric methane emissions of dairy cows fed true protein- or urea-containing diets

Methane is a potent but short-lived greenhouse gas targeted for short-term amelioration of climate change, with enteric methane emitted by ruminants being the most important anthropogenic source of methane. Ruminant production also releases nitrogen to the environment, resulting in groundwater pollution and emissions of greenhouse gas nitrous oxide. We hypothesized that inhibiting rumen methanogenesis in dairy cows with chemical inhibitor 3-nitrooxypropanol (3-NOP) would redirect metabolic hydrogen towards synthesis of microbial amino acids. Our objective was to investigate the effects of 3-NOP on methane emissions, rumen fermentation and nitrogen metabolism of dairy cows fed true protein or urea as nitrogen sources. Eight ruminally-cannulated cows were fed a plant protein or a urea-containing diet during a Control experimental period followed by a methanogenesis inhibition period with 3-NOP supplementation. All diets were unintentionally deficient in nitrogen, and diets supplemented with 3-NOP had higher fiber than diets fed in the Control period. Higher dietary fiber content in the 3-NOP period would be expected to cause higher methane emissions; however, methane emissions adjusted by dry matter and digested organic matter intake were 54% lower with 3-NOP supplementation. Also, despite of the more fibrous diet, 3-NOP shifted rumen fermentation from acetate to propionate. The post-feeding rumen ammonium peak was substantially lower in the 3-NOP period, although that did not translate into greater rumen microbial protein production nor lesser nitrogen excretion in urine. Presumably, because all diets resulted in low rumen ammonium, and intake of digestible organic matter was lower in the 3-NOP period compared to the Control period, the synthesis of microbial amino acids was limited by nitrogen and energy, precluding the evaluation of our hypothesis. Supplementation with 3-NOP was highly effective at decreasing methane emissions with a lower quality diet, both with true protein and urea as nitrogen sources.

Corn and sorghum distiller grains in sheep diets

Dried distiller grains (DDG) represent a protein source alternative in animal feed, but the variation from sources and dietary inclusion level can affect animal nutrition response. We evaluated the effects of replacing soybean meal (SBM) with corn and sorghum DDG in the diet on intake, digestibility, allantoin urinary excretion, and nitrogen (N) balance in sheep. Ten intact male sheep, with body weight (BW) of 22.3 ± 2.7 kg were blocked by BW in two replicated 5 × 5 Latin squares. Each period lasted 15 d and consisted of 10 d for diet adaptation and 5 d for sampling and data collection. We evaluated five isonitrogenous diets in a factorial arrangement (2 × 2 + 1): two DDG sources (corn or sorghum DDG); two DDG levels in diets (150 and 300 g /kg dry matter (DM) diet), and a control diet (corn grain and soybean meal as concentrate sources). Inclusion of DDG (DDG versus control) did not affect dry or organic matter intake, but it reduced crude protein (CP) and organic matter (OM) apparent total-tract digestibilities, and digestible OM intake. No effects of DDG inclusion were observed on allantoin urinary excretion and N balance. No interactions between DDG source and level were detected in all response variables. Sorghum-DDG diets had lower CP apparent total-tract digestibility than corn-DDG diet, and N body retention efficiency 20% lower. Dried distiller grains level increase of 150–300 g/kg DM diet reduced CP and OM apparent total-tract digestibilities, and digestible OM intake. Sorghum-DDG has protein biology value for ruminant 20% lower than corn-DDG, and 150 g DDG/kg DM seems more appropriate inclusion than 300 g DDG/kg DM diet. Replacing a mixture of SBM and corn with DDG reduces the nutritional value of the diet, but the effect depends on the level and source of DDG.