Non-protein nitrogen supplementation on in vitro fermentation profile, methane production, and microbial nitrogen synthesis in a corn silage-based substrate.

Non-protein nitrogen (NPN) supplements improve animal performance in backgrounding diets. However, there is scarce information regarding the effect of different NPN sources and combinations on ruminal fermentation profile. The current study aimed to evaluate the effect of different NPN sources and their combinations on in vitro fermentation, microbial N synthesis, and methane (CH4) production in a backgrounding diet. Incubations were conducted on three separate days for 24 h using corn silage and cotton gin byproduct (70% and 30% of DM, respectively) as substrate. Treatments were control (without NPN), urea, and five different proportions of urea-biuret and nitrate (100:0, 75:25, 50:50, 25:75, and 0:100). Each treatment, except control, was formulated to be isonitrogenous and equivalent to 1% urea inclusion. Ruminal fluid was collected from two ruminally cannulated Angus crossbred steers fed ad libitum corn silage and cotton gin byproduct plus 100 g of a urea-biuret-nitrate mixture. The concentration of volatile fatty acids (VFAs) and ammonia nitrogen (NH3-N) were determined at 12 and 24 h of incubation. Final pH, in vitro dry and organic matter digestibility, total gas production, and concentration of CH4 were determined at 24 h. The supplementation of NPN increased (P < 0.05) the concentration of NH3-N at 12 and 24 h. Although NPN supplementation increased (P < 0.05) the concentration of total VFA and acetate at 12 h, treatments did not differ (P > 0.05) at 24 h. Supplementation of NPN increased (P < 0.05) the proportion of acetate at 12 and 24 h but tended to reduce (P = 0.054) the proportion of propionate only at 12 h. Digestibility and pH were not different (P > 0.05) among treatments. Increasing nitrates in the NPN supplement increased (P < 0.05) the proportion of acetate and reduced (P < 0.05) the proportion of butyrate at 12 and 24 h. The supplementation of NPN increased (P < 0.05) microbial N synthesis. Furthermore, increasing nitrate proportion in the NPN supplement increased (P < 0.05) the microbial N synthesis and efficiency of N use. Supplementation of NPN did not modify (P > 0.05) total gas or CH4 production. However, increasing nitrate proportion in the NPN supplement linearly reduced (P < 0.05) CH4 production. Supplementation of NPN increased NH3-N concentration and microbial N while increasing the inclusion of nitrate decreased the production of CH4 and increased the microbial N synthesis in a corn silage-based substrate under in vitro conditions.

Impact of Supplementing a Backgrounding Diet with Nonprotein Nitrogen on In Vitro Methane Production, Nutrient Digestibility, and Steer Performance.

Two experiments were conducted to evaluate the effect of nonprotein nitrogen (NPN) supplementation on in vitro fermentation and animal performance using a backgrounding diet. In experiment 1, incubations were conducted on three separate days (replicates). Treatments were control (CTL, without NPN), urea (U), urea-biuret (UB), and urea-biuret-nitrate (UBN) mixtures. Except for control, treatments were isonitrogenous using 1% U inclusion as a reference. Ruminal fluid was collected from two Angus-crossbred steers fed a backgrounding diet plus 100 g of a UBN mixture for at least 35 d. The concentration of volatile fatty acids (VFA) and ammonia nitrogen (NH3-N), in vitro organic matter digestibility (IVOMD), and total gas and methane (CH4) production were determined at 24 h of incubation. In experiment 2, 72 Angus-crossbred yearling steers (303 ±â€…29 kg of body weight [BW]) were stratified by BW and randomly allocated in nine pens (eight animals/pen and three pens/treatment). Steers consumed a backgrounding diet formulated to match the diet used in the in vitro fermentation experiment. Treatments were U, UB, and UBN and were isonitrogenous using 1% U inclusion as a reference. Steers were adapted to the NPN supplementation for 17 d. Then, digestibility evaluation was performed after 13 d of full NPN supplementation for 4 d using 36 steers (12 steers/treatment). After that, steer performance was evaluated for 56 d (24 steers/treatment). In experiment 1, NPN supplementation increased the concentration of NH3-N and VFA (P < 0.01) without affecting the IVOMD (P = 0.48), total gas (P = 0.51), and CH4 production (P = 0.57). Additionally, in vitro fermentation parameters did not differ (P > 0.05) among NPN sources. In experiment 2, NPN supplementation did not change dry matter and nutrient intake (P > 0.05). However, UB and UBN showed lower (P < 0.05) nutrient digestibility than U, except for starch (P = 0.20). Dry matter intake (P = 0.28), average daily gain (P = 0.88), and gain:feed (P = 0.63) did not differ among steers receiving NPN mixtures. In conclusion, tested NPN mixtures have the potential to be included in the backgrounding diets without any apparent negative effects on animal performance and warrant further studies to evaluate other variables to fully assess the response of feeding these novel NPN mixtures.

Nonprotein nitrogen (NPN) supplements can be used as a nitrogen source for ruminants fed low-protein diets. The most common NPN source is urea, included typically at a range between 0.5% and 1% of the diet dry matter in growing beef cattle. Although other NPN sources and mixtures are available, there is scarce information regarding their use in ruminant production. Two experiments were conducted to evaluate the effect of NPN sources on in vitro fermentation and animal performance using a backgrounding diet. In experiment 1, three different incubations were performed for 24 h. Treatments were control (without NPN), urea (U), urea­biuret (UB), and urea­biuret­nitrate (UBN) mixtures. In experiment 2, 72 crossbred yearling steers were randomly assigned to one of the following treatments: U, UB, and UBN mixtures. Diets were formulated to contain the same nitrogen concentration in both experiments. In experiment 1, supplementation of NPN increased the in vitro fermentation, but there were no differences among NPN sources. In experiment 2, steers performed similarly among NPN sources. These findings suggest that NPN mixtures have the potential to be included in the backgrounding diets without detrimental effects. Further studies should evaluate other variables (e.g., fermentation dynamic and microbial protein supply) when using these novel mixtures.

Effects of Aspergillus oryzae prebiotic on animal performance, nutrients digestibility, and feeding behavior of backgrounding beef heifers fed with either a sorghum silage- or a byproducts-based diet.

Eighty-four Angus crossbred heifers (13 ± 1 mo of age, 329.5 ± 61.92 kg of body weight [BW]) were used in a generalized randomized block design with a 2 × 2 factorial arrangement of treatments. The factors evaluated were: 1) diet type (whole plant sorghum silage [SS] vs. byproducts-based [BP]), and 2) feed additive: Aspergillus oryzae prebiotic (AOP; 2 g/d) vs. Negative control (CTL; 0 g/d), resulting in four treatments: sorghum silage-control (SC), sorghum silage-AOP (SA), byproducts-control (BC), and byproducts-AOP (BA). Heifers were stratified by body weight (BW), randomly assigned to treatments (21 heifers per treatment) and housed in 12 pens equipped with two GrowSafe feed bunks each to measure individual dry matter intake (DMI). After a 14-d adaptation, BW was measured every 14 d for 56 d. Chewing activity was monitored through collar-mounted HR-Tags (heat-related tags). Following the performance period, apparent total tract digestibility was measured in 40 heifers, using indigestible neutral detergent fiber as a marker. Heifers fed with the BP diets had greater DMI (2.92% vs. 2.59% of BW, P < 0.01) and average daily gain (ADG; 1.16 vs. 0.68 kg, P ≤ 0.01) than heifers fed with SS diets. Compared with BP-fed animals, heifers consuming the SS diets had 23 more visits/d to the feed bunks (P ≤ 0.01), consumed 53% less dry matter on each visit (P ≤ 0.01), and spent 39% more min chewing/d and 63% more min chewing/kg of DMI (P ≤ 0.01). However, chewing measured in min/kg of neutral detergent fiber intake was not affected by treatment (average 111.3 min/kg of NDF intake). Feeding AOP improved gain:feed (GF) by 15% in BP-fed heifers (0.120 vs. 0.104 kg/kg; P < 0.05). Inclusion of AOP increased organic matter digestibility (OMD) in SS diets (55.88% vs. 49.83%; P < 0.01), whereas it decreased OMD in BP diets (61.67% vs. 65.77%; P < 0.05). In conclusion, ADG and GF of BP-fed heifers was greater than SS-fed heifers, and GF was greater with AOP supplementation in BP-fed heifers. Improvement in GF in BP-fed heifers was likely not related to differences in nutrient digestibility as AOP inclusion did not enhance digestibility in the BP diet. Additionally, the effects of the AOP inclusion appear to be diet-dependent, where the 15% improvement in GF by AOP occurred in heifers fed with the more fermentable diet. Therefore, further research should explore the mechanisms responsible for the observed improvements in growth performance when feeding AOP to BP-fed heifers.

This experiment evaluated the effects of the dietary inclusion or not of Aspergillus oryzae prebiotic (AOP; 2 g/d) in two contrasting diets: sorghum silage-based (SS) vs. byproducts-based (BP), on growth performance, nutrient digestibility, and feeding behavior of growing heifers. A total of 84 Angus crossbred heifers were used in the study. Heifers fed with the BP diets had greater feed intake, average daily gain, and final body weight. In addition, heifers fed with the BP diets had reduced number of visits to the feed bunk but consumed more in each visit than heifers fed with the SS diets. Additionally, heifers fed with the BP diets had lesser chewing activity measured in total min/d and in min/kg of dry matter intake; however, chewing activity measured in min/kg of neutral detergent fiber was not influenced by treatments. The inclusion of AOP increased the gain:feed ratio by 15% in heifers fed with the BP diet but did not influence this variable in the SS diet. The inclusion of AOP increased nutrient digestibility in heifers fed with the SS diet and decreased nutrient digestibility in heifers fed with the BP diet. These results show that feeding AOP can enhance growth performance in beef heifers in a diet-dependent manner.

Evaluation of carinata meal or cottonseed meal as protein sources in silage-based diets on behavior, nutrient digestibility, and performance in backgrounding beef heifers.

Changing climatic conditions are imposing risks and diminishing yields in agriculture. Sorghum (Sorghum bicolor) silage is a feasible option for backgrounding beef cattle in terms of economic risk management and animal productivity when compared with corn (Zea mays) silage, due to its drought adaptability. Similarly, Brassica carinata meal has proven to be a viable alternative as a protein supplement in forage-based beef cattle systems, when included at 10% of the diet dry matter (DM). However, research is scarce regarding its inclusion in silage-based diets for backgrounding animals. The objective of this trial was to compare a processor-chopped sorghum silage (SS) against a typical corn silage (CS) in a digestibility and performance trial while supplementing two protein sources; one traditionally used like cottonseed meal (CSM) and one novel like B. carinata meal (BCM). A total of 84 Angus crossbred heifers (307 ± 33 kg BW) were evaluated in a randomized block design with a 2 × 2 factorial treatment arrangement with type of silage and protein source as factors. Diets were fed ad libitum, consisting of 89% silage source plus 10% protein source, and 1% mineral inclusion on DM basis. The experimental period consisted of 14 d of adaptation followed by 5 d of apparent total tract digestibility measurements and 56 d of animal performance and intake behavior measurements. Heifers fed SS showed greater number of daily meals but decreased meal sizes (P ≤ 0.05), not differing in meal length (P > 0.10) when compared with CS. Dry matter and organic matter (OM) digestibility showed a silage type × protein source interaction (P ≤ 0.01), where in CS diets, OM tended to be more digestible with CSM vs. BCM, and it did not differ between protein sources in SS based diets. There was an effect of protein (P ≤ 0.01) on ADF digestibility, where CSM was greater than BCM. No effect of treatment was observed (P ≥ 0.10) on DM intake. Average daily gain (ADG) and gain-to-feed ratio were greater for CS than SS (P ≤ 0.01) regardless of protein source. Although heifers fed CS had greater feed efficiency and digestibility, SS can still be considered a viable option for backgrounding beef heifers, obtaining adequate ADG rates of 0.945 kg/d. Lastly, BCM did not differ from CSM in terms of feed efficiency and animal performance, proving to be a viable alternative protein source in silage-based diets.

Increased atmospheric CO2, rising temperatures, and altered patterns of precipitation can limit the production of certain crops commonly used in agriculture, increasing risk, cost, and availability of feedstuffs. The search for alternative plants that could thrive in these changing scenarios is necessary to provide producers with a broader array of options to feed cattle. In this study, sorghum silage was compared with corn silage as the main dietary ingredient, with either Brassica carinata (carinata) or cottonseed meal as the protein source for growing beef heifers. Variables assessed included intake behavior, digestibility, and performance of beef heifers. Heifers fed sorghum silage gained less than heifers fed corn silage, though they grew at an adequate rate for a replacement heifer. Carinata meal showed similar performance results compared with cottonseed meal, despite some of its fiber components being less digestible in the total tract. Therefore, sorghum silage has potential to be a viable feedstuff for growing beef heifers although it may result in decreased performance compared with corn silage. Alternatively, carinata meal can be a practical alternative to cottonseed meal as a protein source in terms of animal performance. This could translate in an increase in the planted area of both sorghum and carinata in Southern United States, as they are adapted to drought and high temperatures, enhancing the resilience of beef production systems in a context of increased climate variability.

Impacts of polyclonal antibody preparations from avian origin on nutrient digestibility and performance of backgrounding beef cattle.

This study evaluated the effects of feeding an avian-derived polyclonal antibody preparation (PAP; CAMAS, Inc.) against Streptococcus bovis, Fusobacterium necrophorum, and lipopolysaccharides (LPS; 40%, 35%, and 25% of the preparation, respectively) on growth performance (Exp. 1) and apparent total tract digestibility of nutrients (Exp. 2) of beef cattle consuming a backgrounding diet. In Exp. 1, Angus crossbred heifers (n = 70; 360 ± 24 kg of initial body weight; BW) and steers (n = 20; 386 ± 24 kg of BW) were used in a generalized randomized block design. Heifers and steers were allocated to 1 of 18 concrete-surfaced pens (6 pens per treatment) to receive a common ad libitum diet (35% cottonseed hulls, 34% dry-rolled corn, and 20% corn gluten pellets; 15.9% crude protein on a dry matter [DM] basis, 1.58 Mcal/kg DM of net energy [NE] of maintenance, and 0.98 Mcal/kg DM of NE of gain) and 1 of the 3 treatments consisting of feeding 1 (PAP1), 3 (PAP3), or 0 g (CON) of PAP per day for 56 d. Feed intake was recorded daily and BW was obtained on days -1, 0, 14, 28, 42, 55, and 56 to assess average daily gain (ADG), dry matter intake (DMI), and gain:feed (G:F). Plasma concentrations of glucose and haptoglobin were measured on days 0, 14, 28, 42, and 56. In Exp. 2, 25 Angus crossbreed steers (390 ± 24 kg BW) were used in a completely randomized design to receive the same diet and treatments from Exp. 1 (CON: n = 8; PAP1: n = 9; and PAP3: n = 8). Following a 14-d adaptation to diets, feed and fecal samples were collected to determine apparent total tract nutrient digestibility. In Exp. 1, overall BW, DMI, ADG, G:F, and plasmatic measurements did not differ among treatments over the 56-d period (P ≥ 0.16). However, from days 0 to 14, a quadratic effect was observed for ADG, in which cattle receiving PAP1 had greater (P = 0.04) ADG compared with CON. In Exp. 2, no difference in DMI was observed (P = 0.88), yet DM, organic matter, neutral and acid detergent fiber, and starch digestibility were least (P ≤ 0.05) for PAP3, whereas digestibility of neutral detergent fiber was greatest (P < 0.01) for PAP1. In summary, feeding 1 g/d of a PAP against S. bovis, F. necrophorum, and LPS improved growth performance in the first 14 d and increased fiber digestibility of beef cattle consuming a backgrounding diet. Further research is needed to understand the impaired responses on nutrient digestibility when greater doses are provided.

Polyclonal antibody preparations from avian origin as a feed additive to beef cattle: ruminal fermentation during the step-up transition diets.

This study investigated the effects of feeding an avian-derived polyclonal antibody preparation (PAP; CAMAS, Inc.) against Streptococcus bovis, Fusobacterium necrophorum, and lipopolysaccharides (40%, 35%, and 25% of the preparation, respectively) on ruminal fermentation [pH, ammonia-N (NH3-N), lactate, and volatile fatty acids (VFA)] of beef steers during a 21-d step-up diet adaptation. Eight ruminally cannulated Angus crossbred beef steers (658 ± 79 kg of body weight) were assigned in a crossover design to be transitioned from a diet containing ad libitum bermudagrass hay [Cynodon dactylon (L.) Pers.] plus 0.45 kg/d (as fed) of molasses with 0 (CON) or 3 g of PAP (PAP) to a high-grain diet. Transition consisted of three 7-d steps of increased inclusion of cracked corn (35%, 60%, and 82% of the diet DM for STEP1, STEP2, and STEP3, respectively). On each transition day and 7 d after STEP3 (STEP3-7d), ruminal fluid samples were obtained every 3 h for 24 h. Feeding 3 g of PAP daily increased (P < 0.01) average ruminal pH during STEP3 compared with CON steers (5.6 vs. 5.4 ± 0.05, respectively). During STEP1, NH3-N concentration was greater (P < 0.01; 9.4 vs. 6.8 ± 0.74 mM, respectively), and time (min/d) and area (time × pH) of ruminal pH below or equal to 5.2 was lesser (P ≤ 0.03) for steers consuming PAP compared with steers assigned to CON treatment (33.4 vs. 73.3 ± 21.7 min/d and 187.4 vs. 406.3 ± 119.7 min × pH/d, respectively). Steers consuming PAP had greater acetate:propionate ratio at 0, 3, and 6 h relative to diet change compared with CON (2.42, 2.35, 2.29 vs. 1.66, 1.79, and 1.72 ± 0.17, respectively), whereas butyrate molar proportions increased (P = 0.02; 17.1 vs. 11 ± 1.58 mol/100 mol for CON and PAP, respectively) when PAP was not fed at STEP2. Total ruminal lactate concentrations were not affected by PAP feeding (P > 0.11). In conclusion, feeding 3 g/d of polyclonal antibody preparation against S. bovis, F. necrophorum, and lipopolysaccharides was effective in increasing ruminal pH, A:P ratio, and NH3-N concentrations, possibly attenuating the risks of ruminal acidosis in steers during the step-up transition from forage to high-grain diets.

Intake, ruminal fermentation parameters, and apparent total-tract digestibility by beef steers consuming Pensacola bahiagrass hay treated with calcium oxide.

To determine the effect of CaO-treated Pensacola bahiagrass (Paspalum notatum) hay on intake, ruminal fermentation parameters, and apparent total-tract digestibility of nutrients, nine ruminally cannulated Angus-crossbred steers were used in a triplicated 3 × 3 Latin square design. Steers had ad libitum access to either 1) untreated dry hay (DH; n = 8); 2) hay at 50% DM treated with 8.9% CaCO3 (dry matter [DM] basis; CC; n = 9); or 3) hay at 50% DM treated with 5% CaO (DM basis; CO; n = 8). Water was added to reach 50% DM in the CC and CO diets. Ruminal fluid and blood samples were collected every 3 h for 24 h. Ruminal fluid was analyzed for pH, volatile fatty acids (VFA), and ammonia-nitrogen (NH3-N). Blood was analyzed for plasma urea nitrogen (PUN). Hay and fecal samples were collected for 4 d, four times daily for hay and twice daily for feces, to determine apparent total-tract digestibility of nutrients. The hay provided to steers during the digestibility period was analyzed for in vitro organic matter digestibility (IVOMD) for 48 h. Data were analyzed as repeated measures for blood and ruminal fermentation parameters. Total DM intake was not affected (P ≥ 0.674) by treatment. A treatment effect (P < 0.001) was observed for average ruminal pH, where steers consuming CO had the greatest pH (P < 0.001). Ruminal concentration of NH3-N tended (P = 0.059) to be reduced in steers consuming CO. There was a treatment × time interaction (P = 0.023) on concentrations of PUN, where at 3 h DH and CO were lesser than CC (P ≤ 0.050) and at 21 h DH was lesser than CC (P = 0.020). Total VFA, acetate, propionate, butyrate, branched-chain VFA, and valerate concentrations were affected by treatment (P ≤ 0.035), where a reduction (P ≤ 0.034) occurred in steers consuming CO. No treatment differences were observed for total-tract digestibility of DM (P = 0.186), organic matter (P = 0.169), or crude protein (P = 0.152); however, steers consuming DH had greater neutral detergent fiber (P = 0.038) than CC and tended to be greater than CO (P = 0.082). The CO hay had greater (P = 0.005) IVOMD compared with DH and tended (P = 0.100) to be greater than CC. Bahiagrass hay treated with CaO may reduce ruminal fermentation, as indicated by decreased total VFA concentration without altering DM intake. The addition of CaO did not improve the digestibility of bahiagrass hay in vivo; however, in vitro results are contradictory and warrant further elucidation.

With the ever-growing desire to increase efficiency in beef cattle production, researchers have developed strategies such as treating poor-quality forages with chemicals to increase the digestibility of fiber fractions, consequently increasing their energy value for cattle feeding. Calcium oxide has been proposed as a replacement to more caustic chemicals used in the past (e.g., NaOH) and data indicate that it can promote similar and effective outcomes. The current study evaluated the effects of bahiagrass hay treated with calcium oxide on ruminal fermentation parameters, apparent total-tract digestibility of nutrients, and intake by beef steers consuming hay ad libitum as the sole ingredient in their diet. Additionally, in vitro organic matter digestibility was evaluated on the hay provided to steers to assess treatment effectiveness. Results indicated that steers consuming bahiagrass hay treated with calcium oxide had 1) increased pH and reduced volatile fatty acids concentrations in the rumen; 2) reduced or tendency for reduction on total-tract digestibility of fiber fractions; and 3) no effect on intake, all when compared with steers consuming untreated hay. In contrast, in vitro results indicated that organic matter digestibility was increased when the forage was treated with calcium oxide.

Impacts of polyclonal antibody preparations from avian origin as a feed additive to beef cattle: immune responses during the step-up transition diets.

This study investigated the effects of feeding an avian-derived polyclonal antibody preparation (PAP; CAMAS, Inc.) against Streptococcus bovis, Fusobacterium necrophorum, and lipopolysaccharides (LPS; 40%, 35%, and 25% of the preparation, respectively) on immune responses (haptoglobin [Hp], serum amyloid A [SAA], rectal temperature [RT], leukocyte counts, and expression of cell adhesion molecules cluster of differentiation [CD] CD11b, CD14, and CD62L) of beef steers during a 21-d step-up adaptation to a high-grain diet. Eight ruminally cannulated Angus crossbred beef steers (658 ± 79 kg of BW) were assigned in a cross-over design and transitioned from a diet containing bermudagrass hay (Cynodon dactylon (L.) Pers.) ad libitum plus 0.45 kg/d of molasses with 0 (CON) or 3 g of PAP to a high-grain diet. Transition consisted of three 7-d steps of increased inclusion of cracked corn (35%, 60%, and 82% of the diet dry matter for STEP1, STEP2, and STEP3, respectively). On each transition day and 7 d after STEP3 (STEP3-7d), RT was obtained every 3 h for a total of 24 h, whereas blood was collected on days 0, 1, and 3, relative to diet transition. There were no effects of PAP inclusion in any of the blood parameters (P > 0.11). However, a tendency for day effect (P = 0.10) was observed for concentrations of Hp, which were greater on days 3 and 7 vs. day 0 relative to the second diet transition (STEP2). Plasma concentrations of SAA were greater on days 1, 3, and 7 compared to day 0 during STEP1 (P = 0.01), while during STEP2 and STEP3, SAA concentrations increased (P < 0.01) from day 0 to 3. During STEP2, PAP steers tended to have lower (P = 0.08) RT than CON steers. Neutrophil and monocyte counts were the least during STEP3 (P < 0.01), whereas expression of CD11b and CD62L was the least through forage feeding (P < 0.01). Concentration of starch in the diet was correlated to all the variables tested (P ≤ 0.01), except for the percentage of B cells (P = 0.22). Yet only ruminal pH, RT, monocyte, and neutrophil counts presented strong correlation coefficients. In conclusion, the step-up transition from forage to high-grain diets triggered systemic inflammation in beef steers as observed by increased plasma concentrations of Hp, SAA, and expression on adhesion molecules in leukocytes. However, feeding polyclonal antibody preparations against S. bovis, F. necrophorum, and LPS did not provide benefits to mitigate inflammation.

Ruminal in situ degradability of forage components and in vitro organic matter digestibility of warm-season grasses treated with calcium oxide.

An experiment was designed to evaluate the effects of CaO on ruminal in situ degradability (RISD) of forage components and in vitro organic matter digestibility (IVOMD) of warm-season forages. Bahiagrass (Paspalum notatum; BH) or Tifton 85 bermudagrass (Cynodon spp.; BM) hay were stored in 20-L buckets in two consecutive years (n = 4/treatment) as follows: 1) untreated dry BH or BM (DH); 2) hydrated BH or BM stored for 7 d (W7); 3) hydrated BH or BM stored for 14 d (W14); 4) hydrated BH or BM + 5% [dry matter (DM) basis] CaO stored for 7 d (CO5-7); 5) hydrated BH or BM + 5% (DM basis) CaO stored for 14 d (CO5-14); and 6) hydrated BH or BM + 10% (DM basis) CaO stored for 14 d (CO10). With exception of the dry treatment (DH), tap water was added to forages under the remaining treatments to reach a DM concentration of 50%. Ruminal in situ degradability of DM, organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) of BH and BM was determined for 24, 48, and 72 h in two ruminally cannulated steers consuming BH. Data were analyzed as a randomized block design using bucket as the experimental unit. The model included the fixed effect of treatment and the random effect of year. Concentration of NDF was reduced (P < 0.001) when BH and BM were treated with 10% and 5% CaO and compared with DH. However, only CO10 promoted a reduction (P = 0.007) in ADF concentration of BH, whereas CO10 and CO5, regardless of storage length, reduced (P ≤ 0.006) ADF concentration of BM, when compared with DH. At all ruminal incubation time points, a treatment effect (P < 0.001) was observed on RISD of DM, OM, CP, NDF, and ADF of BH and BM, where all treatments containing CaO promoted greater degradability when compared with DH, W7, and W14, which did not differ (P > 0.05). Ruminal degradability of forage components was greatest (P < 0.05) for CO10, followed by CO5-7 and CO5-14, which did not differ (P > 0.05). In vitro organic matter digestibility was increased (P < 0.001) in both BH and BM when CaO was applied and compared to DH. Treatment of BH and BM with CaO seems to be an effective method of promoting increased digestibility of forage components, including fiber fractions, when applied at 5% of the forage DM with potential additional benefits to BH when applied at 10%.

Characterization of dietary protein in Brassica carinata meal when used as a protein supplement for beef cattle consuming a forage-based diet.

As a novel oilseed crop in Florida, Brassica carinata has the capacity of producing high-quality jet biofuel, with a protein-dense meal (~40% crude protein; CP) obtained as a by-product of oil extraction. Characterization of the meal protein is limited, yet necessary for formulation of beef cattle diets; therefore, the objective of this experiment was to determine ruminal and postruminal digestibility of protein from B. carinata. Eight ruminally cannulated Angus crossbred steers (473 ± 119 kg) were used in a duplicated 4 × 4 Latin square design, in which in situ ruminal and postruminal degradability of nutrients were evaluated. The three-step in vitro procedure was used to compare CP and amino acid (AA) degradation in B. carinata meal pellets (BCM) with that of cottonseed meal (CSM), dry distillers grains with solubles (DDGS), and soybean meal (SBM). In situ bags were incubated in the rumen for 0 to 96 hr, with the undegraded supplement remaining after 16 hr subjected to serial in vitro enzymatic solutions. Data were analyzed using the MIXED procedure of SAS. Ruminal rate of degradation of dry matter, organic matter, and CP was greatest (P ˂ 0.01; 10.9, 11.3, and 11.5 %/h, respectively) for SBM. Rumen degradable protein (RDP) content did not differ (P = 0.20; 47.8% and 55.1%, respectively) between CSM and DDGS, but was decreased (P ˂ 0.01) compared with SBM and BCM, which did not differ (P = 0.99; 72.3% and 71.8% RDP, respectively). Compared with DDGS, SBM had greater (P < 0.01) intestinal digestibility of rumen undegradable protein (RUP). Intestinally absorbable digestible protein (IADP) was greatest (P < 0.01) for CSM, with SBM and BCM having the least IADP. Total tract digestibility of CP (TTDP) was greater (P < 0.01) for SBM compared with CSM and DDGS. The contribution of RUP to intestinally absorbable AA was 7.2 and 3.1 g of lysine and methionine per kilogram of CP in BCM, respectively. The evaluation of B. carinata meal as protein supplemented for cattle consuming a forage-based diet resulted in 71.8% RDP and 97.1% TTDP, thus indicating its viability as a high-quality protein supplement for beef cattle.

Effects of bismuth subsalicylate and encapsulated calcium-ammonium nitrate on enteric methane production, nutrient digestibility, and liver mineral concentration of beef cattle.

Two randomized block designs were performed to evaluate the effects of bismuth subsalicylate (BSS) and encapsulated calcium-ammonium nitrate (eCAN) on enteric methane production, nutrient digestibility, liver mineral concentration, and performance of beef cattle consuming bahiagrass hay (Paspalum notatum; ad libitum) and sugar cane molasses [1.07 kg/d; dry matter basis]. Experiment 1, used 25 crossbred steers [335 ± 46 kg of initial body weight (BW)] with a 2 × 2 + 1 factorial arrangement of treatments for two 20 d periods. Factors were nonprotein nitrogen (NPN) source (350 mg/kg BW of nitrate or 182 mg/kg BW of urea), BSS (0 or 58.4 mg/kg BW), and a negative control (NCTRL; bahiagrass hay and molasses only). Steers were re-randomized for a second period (n = 10/treatment total). Intake, apparent total tract digestibility and enteric methane were evaluated. Experiment 2 used 75 crossbred heifers in 25 pens (3 heifers/pen; 279 ± 57 kg of initial BW), consuming the same diet and treatments as experiment 1, to determine liver mineral concentration and growth performance over 56 d. Orthogonal contrasts were used to evaluate the effects of NPN (NCTRL vs. others), source of NPN (NS; urea vs. eCAN), BSS, and NS × BSS. For experiment 1, no interactions were observed for any variables, nor were there any effects of NPN on total tract digestibility of nutrients, except for crude protein. Digestibility of all nutrients was reduced (P ≤ 0.021) for steers consuming eCAN compared with urea. There was no effect (P > 0.155) of BSS on digestibility of nutrients; however, BSS reduced (P = 0.003) apparent S retention. Enteric CH4 emission (g/kg BW0.75) was decreased (P = 0.051) by 11% with the addition of eCAN compared with urea. For experiment 2, no NS × BSS interactions (P ≥ 0.251) were observed to affect liver mineral concentration; however, the addition of BSS decreased liver concentration of Cu (P = 0.002) while increasing Fe concentration (P = 0.016). There was an NS × BSS interaction (P = 0.048) where heifers consuming eCAN and BSS had lesser final BW compared with heifers consuming urea and BSS. While eCAN may be a viable resource for mitigating enteric CH4 production of forage-fed cattle, the negative effects on digestibility should be considered. Furthermore, BSS, at the amount provided, appears to have no negative effects on digestibility of nutrients in forage-fed cattle; however, there may be deleterious impacts on performance depending upon what nitrogen source is supplied.

Apparent total tract digestibility, ruminal fermentation, and blood metabolites in beef steers fed green-chopped cool-season forages.

An experiment was conducted during the winter of two consecutive years to evaluate the effects of feeding green-chopped cool-season forages on digestibility, ruminal fermentation, and blood parameters in beef steers. Nine ruminally cannulated Angus crossbred steers (year 1: 359 ± 79 kg; year 2: 481 ± 105 kg) received ad libitum green-chopped forages from pastures planted with one of the following mixtures: 1) OAT = Horizon 201 oats (Avena sativa L.)/Prine annual ryegrass (Lolium multiflorum Lam.) at 95 and 17 kg/ha, respectively; 2) RYE = FL401 cereal rye (Secale cereale L.)/Prine annual ryegrass (Lolium multiflorum Lam.) at 78 and 17 kg/ha, respectively; or 3) TRIT = Trical 342 triticale (X Triticosecale spp.)/Prine annual ryegrass (Lolium multiflorum Lam.) at 95 and 17 kg/ha, respectively. Intake was measured using the GrowSafe system and orts were discarded prior to subsequent feeding. After a 14-d adaptation, feed and fecal samples were collected twice daily for 4 d to determine apparent total tract nutrient digestibility using indigestible neutral detergent fiber (NDF) as an internal marker. On day 19, blood and ruminal fluid samples were collected every 3 h during a 24-h period to analyze plasma urea nitrogen (PUN) and glucose, ruminal pH, and concentration of ruminal ammonia nitrogen (NH3-N) and volatile fatty acids (VFA). Data were analyzed as a generalized randomized block design with repeated measures using the PROC MIX of SAS. No effect of treatment (P > 0.05) was observed for intake of dry matter, organic matter (OM), crude protein, NDF, or acid detergent fiber. Apparent total tract digestibility of nutrients was greater (P < 0.05) for OAT and TRIT when compared with RYE, with OM digestibility being 82.7%, 79.6%, and 69.5%, respectively. An effect of time (P < 0.01) was observed for ruminal pH. Plasma concentration of glucose was greater (P < 0.01) in steers consuming OAT, whereas steers fed RYE had greater (P < 0.05) concentrations of ruminal NH3-N and PUN, and the least concentration of total ruminal VFA (P < 0.05), despite having the greatest (P > 0.05) molar proportion of acetate, branched-chain VFA, and acetate:propionate. Increased nutrient digestibility and favorable ruminal fermentation and blood metabolites of OAT and TRIT are potentially conducive to enhanced growth performance when compared with RYE.

Effects of bismuth subsalicylate and encapsulated calcium ammonium nitrate on ruminal fermentation of beef cattle.

A replicated 5 × 5 Latin square design with a 2 × 2 + 1 factorial arrangement of treatments was used to determine the effects of bismuth subsalicylate (BSS) and encapsulated calcium ammonium nitrate (eCAN) on ruminal fermentation of beef cattle consuming bahiagrass hay (Paspalum notatum) and sugarcane molasses. Ten ruminally cannulated steers (n = 8; 461 ± 148 kg of body weight [BW]; average BW ± SD) and heifers (n = 2; 337 ± 74 kg of BW) were randomly assigned to one of five treatments as follows: 1) 2.7 g/kg of BW of molasses (NCTRL), 2) NCTRL + 182 mg/kg of BW of urea (U), 3) U + 58.4 mg/kg of BW of BSS (UB), 4) NCTRL + 538 mg/kg of BW of eCAN (NIT), and 5) NIT + 58.4 mg/kg of BW of BSS (NITB). With the exception of NCTRL, all treatments were isonitrogenous. Beginning on day 14 of each period, ruminal fluid was collected and rectal temperature was recorded 4× per day for 3 d to determine ruminal changes every 2 h from 0 to 22 h post-feeding. Ruminal gas cap samples were collected at 0, 3, 6, 9, and 12 h on day 0 of each period followed by 0 h on days 1, 2, 3, and 14. Microbial N flow was determined using Cr-Ethylenediaminetetraacetic acid, YbCl3, and indigestible neutral detergent fiber for liquid, small particle, and large particle phases, respectively. Data were analyzed using the MIXED procedure of SAS. Orthogonal contrasts were used to evaluate the effects of nonprotein nitrogen (NPN) inclusion, NPN source, BSS, and NPN source × BSS. There was no treatment effect (P > 0.05) on concentrations of H2S on day 0, 1, 2, or 14; however, on day 3, concentrations of H2S were reduced (P = 0.018) when NPN was provided. No effect of treatment (P = 0.864) occurred for ruminal pH. There was an effect of NPN source on total concentrations of VFA (P = 0.011), where a 6% reduction occurred when eCAN was provided. There were effects of NPN (P = 0.001) and NPN source (P = 0.009) on the concentration of NH3-N, where cattle consuming NPN had a greater concentration than those not consuming NPN, and eCAN reduced the concentration compared with urea. Total concentrations of VFA and NH3-N were not affected (P > 0.05) by BSS. There was an effect of BSS (P = 0.009) on rectal temperature, where cattle not consuming BSS had greater temperatures than those receiving BSS. No differences for NPN, NPN source, nor BSS (P > 0.05) were observed for microbial N flow. In conclusion, eCAN does not appear to deliver equivalent ruminal fermentation parameters compared with urea, and BSS has limited effects on fermentation.

Evaluation of Brassica carinata meal as a protein supplement for growing beef heifers1,2.

Brassica carinata is a new oilseed crop in Florida with the potential of producing high-quality jet biofuel. A high-protein meal (~40% crude protein; CP) is obtained as a byproduct of oil extraction; however, limited research is available on the utilization of this meal as a protein supplement for beef cattle. A generalized randomized block design was used to evaluate the effects of supplementation with B. carinata meal pellets on performance and attainment of puberty in growing beef heifers consuming bermudagrass hay (Cynodon dactylon) ad libitum. Sixty-four Angus crossbred heifers (240 ± 39 kg initial body weight; BW) were stratified and blocked (2 blocks: light and heavy) by initial BW and randomly allocated into 18 pens over 2 consecutive years (10 in year 1 and 8 in year 2). Within block, pens were randomly assigned to 1 of 2 treatments: 0 (CTL) or 0.3% of BW/d (as fed) of B. carinata meal pellets (BCM). Blood samples and BW were collected weekly for 70 d, before daily supplementation. Data were analyzed using PROC MIXED of SAS with repeated measures. Model included the fixed effects of treatment, day, treatment × day interactions, block, and block × treatment interactions, with the random effect of year. Plasma was analyzed for concentrations of progesterone, triiodothyronine (T3), thyroxine (T4), ceruloplasmin (Cp), and haptoglobin (Hp). An effect of treatment was observed (P ˂ 0.01) for ADG between CTL (0.14 kg) and BCM (0.42 kg). There was no treatment or block (P > 0.05) effect for concentrations of T3, T4, or Hp; however, there was an effect of day (P < 0.01) for T3, T4, and Cp. An effect of treatment (P ˂ 0.01) was observed for Cp, with CTL having greater concentrations compared with BCM. Time to attainment of puberty did not differ (P = 0.93) between treatments. Feeding B. carinata meal as a protein supplement at 0.3% of BW/d is a viable option for increasing ADG of growing beef heifers, without affecting attainment of puberty, thyroid hormone status, or eliciting an acute phase response.

Evaluation of Brassica carinata meal on ruminant metabolism and apparent total tract digestibility of nutrients in beef steers1,2.

Brassica carinata is a new oilseed crop with the potential of producing high-quality jet biofuel. A high-protein meal (~40% crude protein) is obtained as a byproduct of hexane-solvent oil extraction; however, limited research is available on the use of this meal as a protein supplement for beef cattle. A duplicated 4 × 4 Latin square design was used to determine the effects of supplementation with B. carinata meal on ruminal fermentation, digestibility, and blood metabolites in beef cattle consuming bahiagrass hay (Paspalum notatum Flüggé), compared with frequently used protein supplements. Eight Angus crossbred steers (473 ± 119 kg initial BW) were randomly allocated to 8 pens, over 4 periods of 28-d each. Within period, steers were assigned to 1 of 4 treatments: 1) 1.62 kg/d cottonseed meal (CSM); 2) 2.15 kg/d dry distillers grains plus solubles (DDGS); 3) 1.39 kg/d B. carinata meal pellets (BCM); or 4) 1.17 kg/d soybean meal (SBM), supplemented daily, on an isonitrogenous basis. Steers had ad libitum access to bahiagrass hay and water. Intake was measured using the GrowSafe system. Following a 14-d adaptation, feed and fecal samples were collected to determine apparent total tract nutrient digestibility using indigestible NDF as an internal marker. Blood and ruminal fluid samples were collected before providing the protein supplements and then every 3 h, during a 24-h period, to analyze urea nitrogen (PUN) and glucose in plasma, as well as ruminal pH, ammonia nitrogen (NH3-N), and VFA concentrations. Data were analyzed using PROC MIXED of SAS with repeated measures. Model included the fixed effects of treatment, time, treatment × time, square, and period, and the random effects of steer(square) and steer(treatment). No effect of treatment (P > 0.05) was observed for pH, NH3-N, or glucose concentration. An effect of treatment (P < 0.01) was observed for PUN, with steers receiving SBM having greater concentrations. A treatment × time interaction was observed (P < 0.05) for total VFA concentration, acetate to propionate ratio, and molar proportions of acetate, propionate, butyrate, and valerate. Steers consuming SBM had greater molar proportions of branched-chain VFA (P < 0.01) compared with CSM and DDGS. There was no effect of treatment (P > 0.05) on intake or apparent total tract digestibility of nutrients. Brassica carinata performed similarly to commonly used protein supplements indicating its viability as a protein supplement for beef cattle.

Effect of inclusion rate of Fermenten on performance, carcass traits, and apparent total tract digestibility of growing Angus crossbred steers.

In Phase 1 (days 0 to 56) of a two-phase experiment, 81 steers (initial BW = 189 ± 22 kg) were arranged in a generalized randomized block design, allocated to nine pens (nine steers per pen) and assigned to one of three dietary treatments. Treatments consisted of different inclusion rates of Fermenten (FER) in a backgrounding diet fed ad libitum, and were as follows: 0% (CON), 2%, or s FER in the diet DM. Steer was considered the experimental unit, and individual DMI was measured using the GrowSafe system. In Phase 2 (days 57 to 112), treatments were discontinued and steers were relocated to a paddock with free access to a common basal diet, to assess potential residual effects of FER. Effect of treatment was measured on performance, concentration of serum urea nitrogen (SUN), NEFA and glucose, and apparent total tract digestibility of nutrients. On day 56, steers fed 4% FER had lesser (P = 0.01) BW than 2% FER steers. Steers fed CON also tended (P = 0.08) to have greater BW than 4% FER steers. ADG was not different (P = 0.96) between CON and 2% FER steers, whereas steers in the 4% FER treatment had lesser (P ≤ 0.01) ADG than CON and 2% FER. Steers in the 4% FER treatment had lesser (P = 0.04) DMI than CON, and were less feed efficient (P ≤ 0.04) than 2% FER and CON steers. However, DMI as a percentage of the BW did not differ (P = 0.07) across treatments. A treatment effect was observed for final BW on day 112 (P = 0.05), where 4% FER tended (P = 0.07) to have lesser BW than CON. In Phase 2, ADG was not different (P = 0.18) among treatments. However, overall ADG (days 0 to 112) was lesser (P = 0.02) for steers fed 4% FER when compared with CON. There was no difference (P ≥ 0.12) in longissimus muscle area gain or 12th rib fat depth gain. There was a treatment × day interaction for serum concentrations of glucose (P < 0.001), NEFA (P < 0.001), and SUN (P < 0.001). Steers fed 4% FER had greater (P < 0.001) DM, OM, NDF, ADF, and CP apparent total tract digestibility than CON. Similarly, 4% FER steers had greater (P ≤ 0.02) DM, OM, NDF, and ADF digestibility than 2% FER. Results show that although inclusion of FER increased apparent total tract digestibility of nutrients, DMI and overall performance of growing beef cattle were negatively affected, mainly when FER was included at 4% of the diet DM.