Effects of grain processing and supplementation with exogenous amylase on nutrient digestibility in feedlot diets

Effects of High-Concentrate-Induced SARA on Antioxidant Capacity, Immune Levels and Rumen Microbiota and Function in Goats

This study aims to explore the antioxidant, immune, and enzyme metabolism aspects in goats experiencing subacute ruminal acidosis (SARA). Furthermore, we seek to elucidate the relationship between the symbiotic microbiota of goats and their metabolic function. Sixteen goats were equally divided into two groups and fed a normal-concentrate diet (NC, 55% concentrate) or a high-concentrate diet (HC, 90% concentrate) for five weeks. We found that the HC diet reduced the total antioxidant capacity (T-AOC) (p = 0.022) and increased interleukin-1β (IL-1β) (p = 0.015), interleukin-4 (IL-4) (p = 0.008) and interleukin-6 (IL-6) (p = 0.002) concentration of goats. Simultaneously, the HC diet significantly increased the concentrations of alkaline phosphatase (ALP) and amylase (AMY) in the blood and rumen fluid of goats (p < 0.05). Microbial analysis in the rumen of goats revealed that the HC diet decreased bacterial richness and diversity, as evidenced by the changed observed species, Chao 1, PD whole tree and Shannon when compared to the NC diet (p < 0.01). The proportion of Proteobacteria increased while that of Spirochaetes and Fibrobacteres significantly decreased with the HC diet (p < 0.05). The Christensenellaceae_R-7_group and Ruminococcaceae_UCG-010 in rumen was notably decreased when a diet was switched from 55% concentrate diet to 90% concentrate diet (p < 0.05). Additionally, microbial functional potentials deduced that the HC diet significantly increased the abundance of the citrate cycle (TCA cycle) (ko00020) associated with carbohydrate metabolism (p = 0.028). Furthermore, the HC diet significantly increased the glutathione metabolism (ko00480) associated with the metabolism of other amino acids (p = 0.008). Our findings suggested that SARA reduced the total antioxidant capacity and increased levels of inflammatory factors in goats, as well as decreased rumen bacterial species and abundance.

Effects of α-amylase and coated α-amylase supplementation on growth performance, nutrient digestion, and rumen fermentation in Holstein bulls

This study evaluated the impacts of α-amylase (AM) and coated α-amylase (CAM) on bull performance, nutrient digestibility, and ruminal fermentation. This study randomized 60 Holstein bulls of 365 ± 11.5 days of age and 457.5 ± 9.35 kg body weight into three groups: without AM addition, adding AM 0.6 g/kg dry matter (DM), and adding CAM 0.6 g AM/kg DM, separately. This whole experimental period was 80 days, including a 20-day adaptation period and a 60-day data and sample acquisition period. In comparison with the unsupplemented control, dry matter intake (DMI) was unaltered; however, average daily gain (ADG) and feed efficiency (FE) were greater for AM or CAM addition. Bulls receiving AM or CAM supply had greater total-tract nutrient digestibility, ruminal total volatile fatty acids (VFA) content, propionate molar proportion, cellulolytic enzyme and AM activities, and the number of microorganisms. In addition, the activities of AM and trypsin in the jejunum and ileum and glucose, albumin, and total protein concentrations in serum were greater for AM or CAM addition compared to the control. When comparing the supplementation mode of AM, bulls receiving CAM addition had greater ADG and FE. The crude protein and starch digestibility and intestinal AM and trypsin activity were higher, while acid detergent fiber (ADF) digestibility was lower for CAM addition than for AM addition. The lower propionate molar proportion and cellobiase and carboxymethyl cellulase activities, together with Ruminococcus albus, Ruminococcus flavefaciens, and Fibrobacter succinogenes populations were observed for CAM addition compared with AM addition. However, there were greater glucose, albumin, and total protein concentrations in serum after adding CAM. According to the data, the supply of AM improved ADG, nutrient digestion, and rumen fermentation. Notably, the optimum supplementation mode was in the form of CAM in bulls.

Meta-analysis of the effects of the dietary application of exogenous alpha-amylase preparations on performance, nutrient digestibility, and rumen fermentation of lactating dairy cows

Several studies have evaluated the effects of the dietary application of exogenous alpha-amylase preparations (AMA) as a strategy to increase total tract starch digestibility (TTSD) and milk yield (MY) in dairy cows, but the results have been inconsistent. Thus, the objective of this study was to evaluate the effects of the dietary application of AMA on the performance, digestibility, and rumen fermentation of lactating dairy cows using a meta-analytic method. A total of 18 peer-reviewed manuscripts (N = 32 treatment comparisons) from 2003 to 2019 were systematically identified following the PRISMA method. The weighted raw mean differences between dietary AMA and control treatments were compared with a robust variance estimation. Likewise, diet characteristics like crude protein (CP) content, NDF content, starch content, days in milk (DIM), experimental design (Latin square and continuous), and AMA dose (0 to 732 Kilo Novo units (KNU)/ kg TMR) were used as covariates in a meta-regression, subgrouping, and dose-response analysis. Compared to the control, dietary AMA increased (P < 0.05) DM digestibility (69.32 vs. 68.30%), TTSD (94.62 vs. 94.10%), milk protein concentration and yield (3.11 vs. 3.08 %; 1.14 vs. 1.10 kg/d) and tended to increase (P = 0.09) fat-corrected milk (35.96 vs. 35.10 kg/d) but no effects were observed on DM intake (22.99 vs. 22.90 kg/d) and feed efficiency (1.50 vs. 1.48). Dietary AMA tended (P = 0.10) to reduce rumen pH (6.27 vs 6.30). Both, the enzyme dose, and DIM strongly influenced (P < 0.05) the effects of AMA on digestibility and performance. The dose-response analysis revealed that feeding 600 KNU/kg to high-producing early lactation (< 70 DIM) dairy cows increased FCM and milk protein. Accounting for the type of experimental design was associated with a lower between-studies-variance among comparisons. Overall, this meta-analysis supports the hypothesis that dietary AMA supplementation is associated with a better lactational performance in dairy cows. However, these effects are only suitable for high-producing early lactation dairy cows.

Impact of Feeding Syngenta Enogen® Feed Corn Compared to Control Corn in Different Diet Scenarios to Finishing Beef Cattle

Simple Summary

A pooled statistical analysis of seven experiments and 200 pen observations was performed to determine the impact of feeding Enogen^® corn compared to conventional corn grain in beef cattle finishing diets. When the corn was compared as dry-rolled corn in diets with lower inclusion rates of distiller grains plus solubles (less than 20% of the diet), feeding Enogen^® corn improved the efficiency of beef production. That response was a 4.8% improvement due to feeding Enogen^® in a corn-based diet without distiller grains but was 1.8% in diets with 18 to 20% distiller grains. Feeding Enogen^® corn improved the efficiency by 4.5% in diets with another common byproduct, Sweet Bran^®. Cattle performance was similar for Enogen^® and conventional hybrids when processed and fed as high-moisture corn. Feeding Enogen^® corn improves the gain efficiency of finishing cattle compared with conventional corn when fed as dry-rolled corn in diets with less than 20% distillers or diets that include Sweet Bran^® feeds.

Abstract

The objective of this pooled statistical analysis was to evaluate Syngenta Enogen^® Feed Corn (EFC) versus conventional corn (CON) when fed as either dry-rolled corn (DRC) or high-moisture corn (HMC) for effects on finishing beef cattle performance and carcass characteristics. Corns were evaluated in diets with byproduct inclusion rates of 0, 15, 18, 20, and 30% distiller grains or 25 and 35% Sweet Bran^® (a commercial corn gluten feed product). Seven trials (n = 1856) consisting of 200 pen means comparing 26 diet treatments were analyzed using regression in a pooled analysis. When EFC was processed as DRC, the gain efficiency (G:F) improved compared with CON, but the response to feeding EFC decreased from a 4.8% improvement to no improvement compared to CON as distiller grains increased from 0 to 30%, but was significantly improved due to feeding EFC in diets with 0 to 18% distiller grains. Feeding cattle EFC as DRC increased the average daily gain (ADG) and G:F by 4.5% compared with CON corn in diets containing Sweet Bran^®. No improvements in animal performance were observed when cattle were fed EFC compared to CON when processed as HMC in any situation. Feeding Enogen^® corn improved the gain efficiency of finishing cattle compared with conventional corn when processed as dry-rolled corn and fed in diets with less than 20% distillers or diets that include Sweet Bran^®.

Effect of exogenous glucoamylase inclusion on in vitro fermentation and growth performance of feedlot steers fed a dry-rolled corn-based diet

The objective was to evaluate the effect of adding an exogenous glucoamylase (GA) enzyme from the fungus Trichoderma reesei on in vitro fermentation, growth performance, and carcass characteristics of feedlot steers fed a dry-rolled corn (DRC)-based diet. Experiment 1 evaluated three levels of added enzyme (0, 0.24, and 0.72 GA enzyme units) and two corn particle sizes (CPS; 2 and 4 mm) in a factorial arrangement using a 7 h in vitro batch culture fermentation. Addition of GA increased (P < 0.01) in vitro dry matter disappearance by 13% and decreased final pH (P < 0.01). Molar proportion of propionate increased with GA inclusion (P < 0.01). A smaller CPS increased (P < 0.01) in vitro dry matter disappearance and total volatile fatty acid and decreased final pH (P < 0.01). A smaller CPS also decreased (P < 0.01) the molar proportion of acetate and increased (P < 0.01) the molar proportion of butyrate. In experiment 2, Angus × Simmental steers (n = 105; initial body weight [BW] = 329 ± 38 kg) were used to evaluate the inclusion of an exogenous GA on growth performance and carcass characteristics. Steers were fed a basal diet consisting of 60% DRC, 17.5% modified distillers grains with solubles, 12.5% corn silage, and 10% dry supplement on a dry matter basis for 136 d. Steers were blocked by weight and allotted to pens. Pens were randomly assigned to one of three treatments (5 pens/treatment): diet with no GA (CON), low inclusion of GA (122 enzyme units/kg dry matter [DM]; LGA), or high inclusion of GA (183 enzyme units/kg DM; HGA). Inclusion of GA did not affect (P ≥ 0.23) final BW, dry matter intake (DMI), or average daily gain (ADG) for the 136-d feeding period. Feed conversion was affected (P = 0.02) by treatment with steers fed HGA having ~8% greater G:F compared with LGA and CON. Treatment did not affect (P = 0.32) fecal starch. Inclusion of GA did not affect (P ≥ 0.19) carcass traits including hot carcass weight, 12th rib fat thickness, yield grade, longissimus muscle area, or marbling score. Overall, results suggest inclusion of exogenous GA enzyme increased in vitro dry matter disappearance in batch culture and improved feed conversion in steers fed 183 enzyme units/kg DM during the finishing phase.

Effects of exogenous α-amylases, glucoamylases, and proteases on ruminal in vitro dry matter and starch digestibility, gas production, and volatile fatty acids of mature dent corn grain

Two separate experiments were carried out to evaluate the effects of incremental doses of 10 exogenous endo-acting α-amylase and exo-acting glucoamylase; 1LAT (bacterial α-amylase), 2AK, 3AC, 4Cs4, 5Trga, 6Afuga, 7Fvga, and 10Tg (fungal α-amylases, glucoamylases, and α-glucosidase), 8Star and 9Syn (fungal amylase-mixtures; experiment 1) and three exogenous proteases; 11P14L, 12P7L, and 13P30L (bacterial proteases; experiment 2) on in vitro dry matter digestibility (IVDMD) and in vitro starch digestibility (IVSD) of mature dent corn grain using a batch culture system. Incremental doses of the exogenous enzymes (0, 0.25, 0.50, 0.75, and 1.00 mg/g of dried substrate) were applied directly to the substrate (0.5 g of ground corn, 4 mm) in sextuplicate (experiment 1) or quadruplicate (experiment 2) within F57 filter bags, which were incubated at 39 °C in buffered rumen fluid for 7 h. Rumen fluid was collected 2-3 h after the morning feeding from three lactating dairy cows and pooled. Cows were consuming a midlactation total mixed ration (TMR; 1.60 Mcal/kg DM and 15.4%; net energy of lactation and crude protein, respectively). Three independent runs were carried out for each experiment. Data were analyzed as a randomized complete block design using run as the blocking factor. Dose was used as a fixed factor while run was considered a random factor. Linear, quadratic, and cubic orthogonal contrasts were also tested. In experiment 1, enzymes 2AK, 3AC, and 10Tg did not increase (P > 0.10) IVDMD and IVSD, whereas 0.25 mg of enzymes 1LAT, 5Trga, and 8Star increased (P < 0.01) IVDMD by 23%, 47%, and 62% and IVSD by 35%, 41%, and 58%, respectively, compared with the control. Enzymes 4Cs4, 6Afuga, 7Fvga, and 9Syn linearly increased IVDMD and IVSD (P < 0.01). Greatest increases in IVDMD (82.9%) and IVSD (85.9%) resulted with 1 mg of 6Afuga compared to control. In experiment 2, the lowest dose of exogenous proteases 11P14L and 12P7L increased (P < 0.01) IVDMD by 98% and 87% and IVSD by 57% and 64%, respectively, whereas the highest dose of 13P30L increased (P = 0.02) IVDMD by 44.8% and IVSD by 30%, relative to the control. In conclusion, IVSD and IVDMD were increased by one α-amylase, certain glucoamylases, and all proteases tested, with the glucoamylase 6Afuga in experiment 1 and the neutral protease 12P7L in experiment 2, increasing IVDMD and IVSD to the greater extents. Future in vivo studies are required to validate these findings before these enzyme additives can be recommended for improving the digestibility of mature dent corn grain.

Effects of Exogenous Glucoamylase Enzymes Alone or in Combination with a Neutral Protease on Apparent Total Tract Digestibility and Feces D-Lactate in Crossbred Angus Bulls Fed a Ration Rich in Rolled Corn

Simple Summary

Dietary enzyme supplementation, as a feed additive, has been well adopted in monogastric production to increase feed efficiency. However, in ruminants, considerably fewer studies have been done and fewer, if any, commercial enzymes have been adopted as a feeding strategy. Feedlot cattle are commonly fed high-starch diets, with varying starch digestibilities depending on type of grain, and degree of grain processing. Improvement in starch digestibility in low processed grain diets will undoubtedly warrant economic benefits to feedlot producers and reduce environmental impact of intensive beef production. In this study, we have shown that dietary glucoamylase supplementation improved 7 to 13% apparent digestibility of dry matter and starch in bulls fed rolled corn-based diets, suggesting that enzyme (glucoamylase) supplementation could be a promising strategy to improve starch efficiency for finishing beef cattle.

Abstract

The aim of this study was to evaluate the effect of two glucoamylases (GA) and the combination of one GA with a neutral protease on apparent total tract digestibility in beef bulls fed a total mixed ration (TMR) rich in rolled corn. Sixteen Angus beef bulls (266 ± 4.9 kg of initial BW, and 182 ± 1.7 d of age) were distributed in 4 blocks, each block consisted of 4 animals balanced by BW. The experimental design was a 4 × 4 Latin square (4 blocks and 4 periods, 2 w per period). Four treatments were tested; (1) control, (2) GA preparation from Trichoderma reesei (TrGA); (3) GA from Aspergillus fumigatus (AfuGA); (4) AfuGA in combination with a neutral protease from Bacillus amyloliquefaciens (BamPro). Apparent total tract digestibility and fecal D-lactate concentration were analyzed. Enzyme supplementation, regardless of enzyme type, increased apparent total tract digestibility of dry matter (from 66.7% to 73.1% ± 2.01), and starch (from 74.7% to 81.8% ± 2.25), without affecting feces D-lactate concentration. Irrespective of glucoamylase type, glucoamylase supplementation improved apparent digestibility of dry matter and starch, and the addition of a protease did not have additional benefits on nutrient digestibility.

Digestibilidade do amido e comportamento ingestivo de novilhos confinados sob efeito de doses de complexo enzimático em dietas de alta densidade energética

RESUMO O objetivo do presente trabalho foi avaliar a conversão alimentar, a digestibilidade do amido, o comportamento ingestivo e o escore de sobras da dieta e de fezes de novilhos confinados, suplementados com doses do complexo enzimático (0; 2,5; 5,0 e 7,5g animal-1 dia-1) e alimentados com dieta constituída por 85% de grão de milho e 15% de núcleo proteico, vitamínico e mineral, na base seca, isenta de forragem. O delineamento experimental foi o de blocos ao acaso contendo quatro tratamentos e quatro repetições. Trinta e dois novilhos inteiros, ½ sangue Angus Nelore, com idade média de 12 meses e peso vivo médio inicial de 422kg, foram confinados por um período de 77 dias. Cada grama de inclusão de complexo enzimático melhorou a conversão alimentar em 0,1652%, reduziu a matéria seca das fezes em 0,4648% e o tempo de ingestão de água em 0,0068 horas dia-1. A máxima digestibilidade do amido foi alcançada na dose de 5,08g animal-1 dia-1. A inclusão progressiva do complexo enzimático à dieta de alta densidade energética promoveu melhoria na conversão alimentar, redução na matéria seca das fezes e diminuição do tempo de ingestão de água. A dose de 5g animal-1 dia-1 do complexo enzimático aumentou a digestibilidade do amido.

Effects of exogenous fibrolytic and amylolytic enzymes on ruminal fermentation and performance of mid-lactation dairy cows

Lactation diets are composed mostly of carbohydrates that are not fully fermented by rumen microbes. The aim of this study was to evaluate exogenous fibrolytic (Fibrozyme, Alltech Inc., Nicholasville, KY) and amylolytic (Amaize, Alltech Inc.) enzymes on nutrient intake, sorting index, total-tract apparent digestibility, ruminal fermentation, nitrogen utilization, milk yield, and composition of dairy cows in mid-lactation. Thirty-two multiparous Holstein cows (181 ± 35 d in milk, 571 ± 72.7 kg of body weight, and 29.6 ± 5.24 kg/d of milk yield at the start of experiment) were blocked according to milk yield and randomly allocated to treatments in a 4 × 4 Latin square design. Treatments were (1) control, basal diet without exogenous enzymes; (2) fibrolytic enzyme (FIB), dietary supplementation of Fibrozyme at 12 g/d (51 IU of xylanase activity/kg of diet dry matter); (3) amylolytic enzyme (AMY), dietary supplementation of Amaize at 8 g/d (203 fungal amylase units/kg of diet dry matter); and (4) both fibrolytic and amylolytic enzymes (FIB+AMY) added at the same dose of the individual treatments. Enzyme products were added to the concentrate during its preparation (once a week). The supply of FIB and AMY had no effect on nutrient intake and digestibility. However, an interaction effect was observed on sorting index of feed particle size between 8 and 19 mm. Amylolytic enzyme increased the sorting for feed particles between 8 and 19 mm, only when fed without FIB. In addition, AMY decreased the sorting for feed with particle size greater than 19 mm. An interaction effect was observed between FIB and AMY for ruminal butyrate concentration and N excretion. Amylolytic enzyme increased ruminal butyrate concentration in cows treated with FIB. Further, FIB decreased milk protein production and feed efficiency only in cows not fed AMY. Amylolytic enzyme reduced urinary N excretion. Exogenous enzymes had no effect on milk production and composition of dairy cows. This study lacks evidence that fibrolytic and amylolytic enzymes can affect nutrient digestibility, ruminal fermentation, and performance of mid-lactation cows.

Feeding the combination of essential oils and exogenous α-amylase increases performance and carcass production of finishing beef cattle

Two experiments were conducted to evaluate the performance responses of finishing feedlot cattle to dietary addition of essential oils and exogenous enzymes. The treatments in each experiment consisted of (DM basis): MON-sodium monensin (26 mg/kg); BEO-a blend of essential oils (90 mg/kg); BEO+MON-a blend of essential oils plus monensin (90 mg/kg + 26 mg/kg, respectively); BEO+AM-a blend of essential oils plus exogenous α-amylase (90 mg/kg + 560 mg/kg, respectively); and BEO+AM+PRO-a blend of essential oils plus exogenous α-amylase and exogenous protease (90 mg/kg + 560 mg/kg + 840 mg/kg, respectively). Exp. 1 consisted of a 93-d finishing period using 300 Nellore bulls in a randomized complete block design. Animals fed BEO had higher DMI (P < 0.001) but similar feed efficiency to animals fed MON (P ≥ 0.98). Compared with MON, the combination of BEO+AM resulted in 810 g greater DMI (P = 0.001), 190 g greater average daily gain (P = 0.04), 18 kg heavier final body weight (P = 0.04), and 12 kg heavier hot carcass weight (P = 0.02), although feed efficiency was not significantly different between BEO+AM and MON (P = 0.89). Combining BEO+MON tended to decrease hot carcass weight compared with BEO alone (P = 0.08) but not compared with MON (P = 0.98). Treatments did not impact observed dietary net energy values (P ≥ 0.74) or the observed:expected net energy ratio (P ≥ 0.11). In Exp. 2, five ruminally cannulated Nellore steers were used to evaluate intake, apparent total tract digestibility of nutrients, and ruminal parameters in a 5 × 5 Latin square design. Feeding BEO increased the total tract digestibility of CP compared to MON (P = 0.03). Compared to MON, feeding the combination of BEO+MON increased the intake of CP (P = 0.04) and NDF (P = 0.05), with no effects on total tract digestibility of nutrients (P ≥ 0.56), except for a tendency (P = 0.09) to increase CP digestibility. Intakes of all nutrients measured, except for ether extract (P = 0.16) were greater in animals fed BEO+AM when compared with MON (P ≤ 0.03), with no differences on total tract nutrient digestibilities (P ≥ 0.11) between these two treatments. In summary, diets containing the BEO used herein enhanced DMI of growing-finishing feedlot cattle compared with a basal diet containing MON without impair feed efficiency. A synergism between BEO and AM was detected, further increasing cattle performance and carcass production compared to MON.

Effects of Syngenta Enogen Feed Corn containing an α-amylase trait on finishing cattle performance and carcass characteristics

Two experiments evaluated the effects of feeding a new corn hybrid, containing an α-amylase enzyme trait, Syngenta Enogen Feed Corn (SYT-EFC), on feedlot performance and carcass characteristics at two locations. Experiment 1 utilized 300 calffed steers (298.5 ± 16.3 kg of BW) at the University of Nebraska–Lincoln Eastern Nebraska Research and Extension Center Mead, NE. Treatments were designed as a 2 × 2 + 1–factorial arrangement with factors consisting of 1) corn type (SYT-EFC or conventional [CON]) and 2) byproduct type (with or without Sweet Bran [SB]), or a BLEND of STY-EFC and CON without SB. In Exp. 2, 240 crossbred, calf-fed steers (287.6 ± 15.4 kg of BW) were utilized at the University of Nebraska–Lincoln Panhandle Research and Extension Center near Scottsbluff, NE. Steers were fed SYT-EFC, CON, BLEND, or CON with a commercial α-amylase enzyme supplement (CON-E). In Exp. 1, there was an interaction for ADG (P = 0.05) and G:F (P = 0.02). Steers fed SYT-EFC with SB had greater ADG and G:F than CON; however, in diets without SB, SYT-EFC and CON were not different resulting in a 10.1% change in G:F when steers were fed SYT-EFC in SB compared with CON and only 1.6% change between SYT-EFC and CON without SB. Energy values, based on performance data, resulted in a 6.5% and 8.3% change in NE_m and NE_g, respectively, for steers fed SYT-EFC and CON with SB and 1.6% change for both NE_m and NE_g for steers fed SYT-EFC and CON without SB. For the main effect of corn trait, steers fed SYT-EFC had greater marbling scores, fat depth, and calculated yield grade compared with CON (P ≤ 0.03). In diets without SB, there was no difference between SYT-EFC, CON, or BLEND for DMI, final BW, ADG, G:F, NEm, or NEg (P ≥ 0.35). In Exp. 2, cattle fed SYT-EFC, BLEND, or CON-E had greater final BW, ADG, and G:F than cattle fed CON (P ≤ 0.03). On average, NE_m and NE_g were 4.9% and 7.0% greater, respectively, for steers fed amylase enzyme treatments compared with CON (P ≤ 0.01). Hot carcass weights were greater in steers fed α-amylase treatments compared with CON (P < 0.01). Feeding Syngenta Enogen Feed Corn, which contains an α-amylase enzyme trait, at both locations improved feed efficiency in finishing cattle diets containing WDGS or SB.

Skeletal muscle and liver gene expression profiles in finishing steers supplemented with Amaize

Our main objective was to evaluate the effects of feeding α-amylase (Amaize, Alltech Inc., Nicholasville, KY, USA) for 140 days on skeletal muscle and liver gene transcription in beef steers. Steers fed Amaize had lower average daily gain (p = .03) and gain:feed ratio (p = .05). No differences (p > .10) in serum metabolites or carcass traits were detected between the two groups but Amaize steers tended (p < .15) to have increased 12th rib fat depth. Microarray analysis of skeletal muscle revealed 21 differentially expressed genes (DEG), where 14 were up-regulated and seven were down-regulated in Amaize-fed steers. The bioinformatics analysis indicated that metabolic pathways involved in fat formation and deposition, stress response, and muscle function were activated, while myogenesis was inhibited in Amaize-fed steers. The quantitative PCR results for liver revealed a decrease (p < .01) in expression of fatty acid binding protein 1 (FABP1) and 3-hydroxybutyrate dehydrogenase 1 (BDH1) with Amaize. Because these genes are key for intracellular fatty acid transport, oxidation and ketone body production, data suggest a reduction in hepatic lipid catabolism. Future work to investigate potential positive effects of Amaize on cellular stress response, muscle function, and liver function in beef cattle appears warranted.

Nutritional strategies in ruminants: A lifetime approach

This review examines the role of nutritional strategies to improve lifetime performance in ruminants. Strategies to increase ruminants' productive longevity by means of nutritional interventions provide the opportunity not only to increase their lifetime performances and their welfare, but also to decrease their environmental impact. This paper will also address how such nutritional interventions can increase herd efficiency and farm profitability. The key competencies reviewed in this article are redox balance, skeletal development and health, nutrient utilization and sustainability, which includes rearing ruminants without antibiotics and methane mitigation. While the relationships between these areas are extremely complex, a multidisciplinary approach is needed to develop nutritional strategies that would allow ruminants to become more resilient to the environmental and physiological challenges that they will have to endure during their productive career. As the demand of ruminant products from the rapidly growing human world population is ever-increasing, the aim of this review is to present animal and veterinary scientists as well as nutritionists a multidisciplinary approach towards a sustainable ruminant production, while improving their nutrient utilization, health and welfare, and mitigation of their carbon footprint at the same time.

Board-invited review: Opportunities and challenges in using exogenous enzymes to improve ruminant production

The ability of ruminants to convert plant biomass unsuitable for human consumption into meat and milk is of great societal and agricultural importance. However, the efficiency of this process is largely dependent on the digestibility of plant cell walls. Supplementing ruminant diets with exogenous enzymes has the potential to improve plant cell wall digestibility and thus the efficiency of feed utilization. Understanding the complexity of the rumen microbial ecosystem and the nature of its interactions with plant cell walls is the key to using exogenous enzymes to improve feed utilization in ruminants. The variability currently observed in production responses can be attributed to the array of enzyme formulations available, their variable activities, the level of supplementation, mode of delivery, and the diet to which they are applied as well as the productivity level of the host. Although progress on enzyme technologies for ruminants has been made, considerable research is still required if successful formulations are to be developed. Advances in DNA and RNA sequencing and bioinformatic analysis have provided novel insight into the structure and function of rumen microbial populations. Knowledge of the rumen microbial ecosystem and its associated carbohydrases could enhance the likelihood of achieving positive responses to enzyme supplementation. The ability to sequence microbial genomes represents a valuable source of information in terms of the physiology and function of both culturable and unculturable rumen microbial species. The advent of metagenomic, metatranscriptomic, and proteomic techniques will further enhance our understanding of the enzymatic machinery involved in cell wall degradation and provide a holistic view of the microbial community and the complexities of plant cell wall digestion. These technologies should provide new insight into the identification of exogenous enzymes that act synergistically with the rumen microbial populations that ultimately dictate the efficiency of feed digestion.