Mixed Ration Research Articles

An in vitro evaluation of partial energy replacement in a total mixed ration with volatile fatty acids derived from agro-industrial residues

AbstractThe scientific interest in volatile fatty acids (VFAs) as an energy source and chemical precursor in ruminant diets has been longstanding, as it has significant implications for animal physiology and well-being. The present study explores the substitution of volatile fatty acids (VFAs) derived from agro-food residues via acidogenic fermentation as an alternative energy source in ruminant feed. Utilizing the gas production method, rumen digestibility assays were conducted, wherein the recovered VFA effluent from the acidogenic fermentation of apple pomace and potato protein liquor was substituted for 10%, 20%, and 30% of the total mixed ration (TMR) energy. Various parameters such as gas, VFA yield and composition, VFA peak intervals, changes in pH, and ammonium nitrogen content were investigated. Based on the results obtained, provision of 20% and 30% of the energy with VFAs did not increase methane production or did not cause significant pH alternations. Nevertheless, such supplementation resulted in increased production and accumulation of VFAs in the rumen media. The bioconversion of agro-food side streams into VFAs opens a new path in sustainable nutrient recovery and feed production from low value agro-industrial residues. Graphical Abstract

In vitro and in sacco evaluation of total mixed ration silage added different levels of chitosan

In vitro and in sacco evaluation of total mixed ration silage added different levels of chitosan

Effect of combining the methanogenesis inhibitor 3-nitrooxypropanol and cottonseeds on methane emissions, feed intake, and milk production of grazing dairy cows

No single enteric CH4 mitigating strategy has been consistently effective or is readily applicable to ruminants in grassland systems. When CH4 mitigating strategies are effective under grazing conditions, mitigation is mild to moderate at best. A study was conducted to evaluate the potential of combining two CH4 mitigation strategies deemed feasible to apply in grazing dairy cows, the methanogenesis inhibitor 3-nitrooxypropanol additive (3-NOP) and cottonseed supplementation (CTS), seeking to enhance their individual CH4 mitigating potential. Forty-eight dairy cows were evaluated in a continuous grazing study and supplemented with either a starch-based concentrate (STA) or one that contained cottonseeds (1.75 kg DM/d; CTS), and with either 19 g/d of 10% 3-NOP (Bovaer®) or the additive’s carrier (placebo), in a 2 × 2 factorial arrangement of treatments. Treatments were supplied mixed with a concentrate supplement (5 kg/d as fed) and offered in two equal rations at milking. Methane emissions were measured on weeks 4 and 8 using the sulphur hexafluoride tracer gas technique over a 5-d period. The 3-NOP and CTS treatments tended to interact on absolute CH4 such that 3-NOP decreased CH4 by 13.4% with STA, but there was no mitigation with 3-NOP and CTS. Treatment interactions were also obtained for CH4 yield, where 3-NOP tended to decrease CH4 when supplied with STA, and tended to increase it with CTS. The increase in CH4 yield with the CTS diet was driven by a numerical decrease in DM intake. Methane intensity was not affected by the 3-NOP or CTS treatments. Total volatile fatty acids in ruminal fluid were not affected by 3-NOP supplementation, but a reduction in acetate and an increase in propionate proportion occurred, resulting in decreased acetate: propionate. The 3-NOP additive decreased grass intake; however, energy−corrected milk yield and milk composition were largely unaffected. Milk urea increased with 3-NOP supplementation. Combining twice daily supplementation of 3-NOP and CTS did not enhance their CH4 mitigation potential when fed to grazing dairy cows. The relatively low inhibition of CH4 production by 3-NOP compared to studies with total mixed rations may result from the mode of delivery (pulse dosed twice daily) and time gap caused by experimental handling and moving of animals to pasture after 3-NOP supplementation in the milking parlour, which could have impaired the synchrony between the additive presence in the rumen and grass intake in paddocks.

Scaling-up fungal pretreatment of lignocellulose biomass: Impact on nutritional value, ruminal degradability, methane production, and performance of lactating dairy cows

Scaling-up fungal pretreatment of lignocellulose biomass (LCB) for ruminant nutrition has become a major research challenge in recent years. This study systematically investigated the effectiveness of fungal (Pleurotus ostreatus) pretreatment (for 30 days under solid state fermentation (SSF)) of large quantities (8400 kg) of lime-pasteurized wheat straw, in terms of improvement in nutritional value, in vitro ruminal fermentation characteristics and methane (CH4) production potential. We further investigated the effects of stepwise replacement of untreated wheat straw (UTWS) with the lime pasteurized P. ostreatus treated wheat straw (PTWS) on dry matter intake (DMI), apparent total tract digestibility, production performance, CH4 emission and feed efficiency of lactating dairy cows. The results revealed that PTWS had lower lignin (P< 0.001), hemicellulose (P< 0.001) and cellulose (P< 0.05) contents and higher crude protein (CP; P< 0.001) content and cellulose to lignin ratio (P< 0.01), as compared to UTWS. The PTWS had higher in vitro DM digestibility (IVDMD; P< 0.001), total gas production (IVGP; P< 0.01), total volatile fatty acids (VFAs, P< 0.01) and propionate (P< 0.05) concentration, and lower (P< 0.05) pH and CH4 gas production during 72 h in vitro fermentation. Notably, the fungus degraded 33.3 % lignin at the expense of 6.56 % cellulose, and markedly increased CP content (46.3 %), IVDMD (20.2 %), IVGP (16.8 %) and VFAs (10.0 %) production, and decreased CH4 production (10.3 %). The aflatoxin B1 concentration of PTWS was <5.0 µg/kg, and mycelium concentration was 181.9 mg/kg DM, reflecting safe and effective tretment of the straw. Replacement of 32 % UTWS in total mixed ration with the PTWS, increased DMI (0.84 kg/day; P = 0.01), apparent total tract DM digestibility (5.5 g/100 g; P< 0.05) and milk yield (1.17 liter/day; P= 0.032), and decreased CH4 emission (1.45 g/kg DMI; P< 0.05). In conclusion, hydrated lime can replace traditional high-tech pasteurization methods for the fungal pretreatment of LCB, and present prospects for scaling up the process for ruminant nutrition.

Efeito de um aditivo fúngico multiespécie no perfil de fermentação ruminal, de-gradabilidade e cinética de produção de gases

Two experiments evaluated the effect of a multispecies fungal complex (BP, BIOPREMIX MX®, Ruminal Fermentation Tech, Uruguay). In Experiment 1 (E1), the impact of adding BP to a total mixed ration (TMR) on ruminal fermentation profile and TMR in situ degradation kinetics was assessed. In Experiment 2 (E2), the effect of adding BP to various substrates on in vitro fermentability was examined. In E1, 4 Holstein cows with rumen cannulas were randomly assigned to Control (TMR with forage:concentrate ratio 75:25) or Control + 120 g/cow/d of BP (BP) and received ad libitum TMR for 30 days. Samples of TMR were ruminally incubated to estimate in situ degradation kinetic. Ruminal pH, ammonia, and volatile fatty acids (VFA) concentrations were measured just before feeding, 4 h and 8 h post feeding. In E2, a factorial arrangement included two BP levels (0 -Control or 6.5 g BP per kg dry matter incubated-WBP) and 8 substrates. In vitro gas production kinetics (GPk), dry matter digestibility (IVDMD), methanogenic potential (CH4), partitioning factor (PF), VFA, and microbial crude protein (MCP) were estimated. The BP increased proportion of propionate (P ≤ 0.05) and reduced ketogenic:glucogenic ratio and Lag phase of NDF (P ≤ 0.05). WBP tended to increase IVDMD, and substrate affected GPk, IVDMD, CH4, PF, VFA and MCP (P ≤ 0.01). Overall, BP improved ruminal metabolism favoring a more glucogenic profile, a shortening Lag phase in NDF degradation, and increasing IVDMD.

Diet supplementation with Saccharomyces cerevisiae influences the electrophoretic parameters in blood in young Charolaise bulls.

The objective of the research was to investigate the effect of Saccharomyces cerevisiae supplementation on some acute-phase proteins, haptoglobin and all electrophoretic parameters in young Charolaise bulls. Sixty bulls were divided into two equal groups: the control group (CG) receiving the base diet without yeast supplementation and the diet supplementation group (YG) receiving the base diet with 5g of Saccharomyces cerevisiae supplementation. The base diet was total mixed ration allocated at 11.85 kg per animal per day. Blood samples were collected from all bulls on day 0 before the start of the diet supplementation, and on days 20 and 40 after the start. Total proteins, albumin, globulin fraction (α1-, α2-, β1-, β2- and γ-globulins), albumin: globulin ratio (A: G) and haptoglobin were determined. Two-way analysis of variance showed a significant effect of the yeast feeding time on all studied parameters except α2-globulins in both groups. The YG showed a higher average concentration of total proteins, albumin and A: G and a lower average concentration of γ-globulins and haptoglobin than the CG. These results indicated the beneficial effect of the Saccharomyces cerevisiae on the inflammatory status of the young bulls, which showed an adequate response in serum levels of the acute-phase proteins tested.

Effect of source and frequency of rumen-protected protein supplementation on mammary gland amino acid metabolism and nitrogen balance of dairy cattle

The AA profile of MP affects mammary gland metabolism and milk N efficiency of dairy cattle. Further, the frequency of dietary protein supplementation may influence N partitioning leading to reduced N excretion. This study investigated the effect of source and frequency of rumen-protected (RP) protein supplementation on apparent total-tract digestibility, milk production, mammary gland AA metabolism, and N balance of dairy cattle. Twenty-eight Holstein-Friesian cows (2.3 ± 0.9 lactations; 93 ± 27 DIM; mean ± SD) were used in a randomized complete block design and fed a basal TMR consisting of 41% corn silage, 32% grass silage, and 27% concentrate (DM basis) and formulated to meet 100% and 95% of net energy and MP requirements, respectively. Cows were adapted to the basal TMR in a freestall barn for 7 d, moved to individual tiestalls for 13 d of adaptation to dietary treatments, and then moved into climate respiration chambers for a 4-d measurement period. Treatments consisted of the basal TMR (CON; 159 g CP/kg DM) or the basal TMR including 1 of 3 iso-MP supplements: (1) 315-g mixture of RP soybean meal and RP rapeseed meal fed daily (ST-RPSR), (2) 384-g mixture of RP His, RP Lys, and RP Met fed daily (ST-RPAA), and (3) 768-g mixture of RP His, RP Lys, and RP Met fed every other day (OS-RPAA). The basal TMR with the addition of treatment supplements was designed to deliver 100% of required MP over a 48-h period. The mixture of His, Lys, and Met was formulated to deliver digestible AA in amounts relative to their concentration in casein. Compared with ST-RPSR, ST-RPAA increased milk protein and fat concentration, increased the arterial concentration of total His, Lys, and Met (HLM), decreased mammary clearance of HLM, and increased clearance of Phe, Leu, and Tyr (tendency for Leu and Tyr). Rumen-protected protein source did not affect N balance, but the marginal use efficiency (efficiency of transfer of RP protein supplement into milk protein) of ST-RPAA (67%) was higher than that of ST-RPSR (17%). Milk protein concentration decreased with OS-RPAA compared with ST-RPAA. Arterial concentration of HLM increased on the nonsupplemented day compared with the supplemented day with OS-RPAA, and there was no difference in arterial HLM concentration across days with ST-RPAA. Mammary uptake of HLM tended to increase on the nonsupplemented day compared with the supplemented day with OS-RPAA. Supplementation frequency of RP AA did not affect N balance or overall milk N efficiency, but the marginal use efficiency of OS-RPAA (49%) was lower compared with ST-RPAA. Overall, mammary glands responded to an increased supply of His, Lys, and Met by reducing efflux of other EAA when RP His, RP Lys, and RP Met were supplemented compared with RP plant proteins. Mammary glands increased sequestration of EAA (primarily HLM) on the nonsupplemented day with OS-RPAA, but supplementing RP AA according to a 24-h oscillating pattern did not increase N efficiency over static supplementation.

Effect of grinding or rolling fava beans on feed intake and milk production in Holstein cows

The objective of the present study was to evaluate the performance of primi- and multiparous dairy cows fed diets with ground or rolled fava beans (FB). A total of 96 Danish Holstein cows (48 primi- and 48 multiparous) were used in a randomized block design lasting 4 weeks. Within parity group, cows were blocked according to their milk yield in 6 blocks with 8 cows each and two cows from each block were distributed in pens where they were assigned randomly one of the two experimental diets. The diets were based on a total mix ration (TMR) composed of 52.6 % forage and 47.4 % concentrate (DM basis), differing only in the particle size of FB (geometric mean diameters of 1.02 and 3.52 mm for ground and rolled FB, respectively). Feed intake, milk production, and milk composition were determined during the last 8 days of the experimental period; none of these differed between treatments except for a higher (P = 0.01) milk N efficiency (% of N intake) and milk urea content with ground FB compared with rolled FB. Additionally, feces and ruminal fluid were collected from a group of 24 multiparous cows to determine fecal starch content and ruminal volatile fatty acids (VFAs). The fecal starch concentration was greater with rolled FB showing a reduced starch digestion, whereas ruminal VFA proportions generally did not differ between treatments. In conclusion, the lactation performance of dairy cows appeared not to be affected by grinding or rolling of FB with a 20 % FB inclusion in the DM diet, even though total tract starch digestion was reduced with greater FB particle size.

Rapid detection of microplastics in feed using near-infrared spectroscopy

The presence of microplastics in the forage and feedstuffs of domestic animals represents an imminent threat to the entire food chain that may reach humans since the particles could be transferred into the intestinal barriers and contaminate blood and animal products. Until now, there is no simple, rapid, sustainable, and reliable method to detect microplastics in animal feed. The objective of this study was to investigate the ability of near-infrared spectroscopy (NIRS) to detect microplastics in ruminant feeds. Two types of instruments were tested using four feeds (corn silage, mixed hay, rye grass silage, soybean meal) and a total mixed ration. Two types of crumbled contaminants, low-density polyethylene and polystyrene, were accurately mixed at ratios of 0, 1, 3, and 5 mg g-1. The pool of the five matrices examined by the benchmark instrument (714-3333 nm) yielded an accuracy of approximately 0.8 mg g-1 and a detection limit of about 1 mg g-1, however, the errors could be halved in separate calibrations. A short wavelength range (714-1070 nm) or a smart NIRS instrument proved an acceptable discrimination of the concentrations. Following these preliminary results, any validation on other samples with different and powerful NIRS tools is encouraged.

Semen characteristics and hormonal profile of Yankasa rams fed a mixed ration of cowpea husk (Vigna unguiculata L. Walp) and tiger nuts (Cyperus esculentum L.) residue

Thirty growing and healthy Yankasa rams were randomly allotted five dietary treatments with six animals per treatment to ascertain the effect of diet on their reproductive potential and hormonal profile. Treatments compared were T1 (cowpea husk 40% + tiger nuts residue 0%), T2 (cowpea husk 30% + tiger nuts residue 10%), T3 (cowpea husk 20% + tiger nuts residue 20%), T4 (cowpea husk 10% + tiger nuts residue 30%), and T5 (cowpea husk 0% + tiger nuts residue 40%). The results of the chemical composition of the diets showed that the dry matter was high for all treatments. The semen characteristics and hormonal profile showed significant differences (p &lt; 0.05) in all the parameters observed but were within normal ranges. However, the group fed a high percent tiger nut mixed ratio had a depreciating effect on semen characteristics, and LH, FSH, and testosterone levels. There is no deleterious effect on the reproductive potential of growing Yankasa rams fed varying levels of cowpea husk and tiger nut residue at the inclusion levels in this study. Hence, it is safe to feed breeding rams the ration mix. However, the authors advise caution of including tiger nuts levels of up to 40% in a mixed ration. further investigation may be conducted with ewes to determine the effect of a mixed ration of cowpea husk and tiger nut residue in reproduction.

Trace mineral testing in Ontario cow-calf operations

There is much confusion surrounding trace mineral supple­mentation in cattle, particularly on cow-calf operations. Because a total mixed ration is rarely utilized, it can be chal­lenging to determine the amount of mineral that cattle are con­suming on a daily basis. When producers have health concerns in their herd that may be tied back to trace mineral consump­tion, the veterinarians struggle to determine if supplementa­tion was appropriate and which tests are the most effective to examine trace mineral status in the cows. The objective of this study was to examine the trace mineral status of cows on cow-calf operations in Ontario and understand more about the sup­plementation strategies that were being used.

Changing industries and shifting gears

Changing from being a self-employed private practice vet­erinarian to working as a consultant for a large corporation requires self-awareness in what you like, dislike, excel at and require more training for. Audits on different facets of a dairy provide individuals the opportunity to use their brain more than their bodies; however, implementing consulting into a practice model is going to differ based on the clientele, the vet­erinarian and the interests of that veterinarian. Total mixed ration (TMR), parlor, heat, calf and data audits are all ways in which veterinarians can become more involved in a consult­ing role on the dairy and a valued team member. There are advantages and disadvantages to working in industry and an individual must weigh those options to decide what works best for them. In the end, the dairy industry and the veterinary pro­fession are changing, and we must evolve with the needs of the clients and customers we serve if we are going to continue to be a valued member of the team.

Rumen fermentation and nutrient utilization of growing Yankasa rams fed a mixed ration containing tiger nut (Cyperus esculentus) residue and cowpea husk (Vigna unguiculata L. Walp)

Thirty (30) Yankasa growing rams were used to investigate the effect of feeding cowpea husk and tiger nut residue in a mixed ration on the rumen ecology, nutrient intake, nutrient digestibility, and nitrogen balance of Yankasa rams. Significant differences (p &lt; 0.05) were observed in the rumen ecology, nutrient intake, nutrient digestibility, and nitrogen balance between the treatments. Rumen ecology was influenced by the diet, with variations in rumen pH, temperature, and volatile fatty acid production. The results indicated that the highest rumen pH and temperature were observed in Treatment 2, while acetate, butyrate, and propionate levels varied among treatments. Nutrient intake and digestibility were significantly affected by the diet. Dry matter intake, crude protein intake, nitrogen detergent fiber (NDF), and acid detergent fiber (ADF) intake varied among treatments. Treatment 3 showed the highest dry matter intake, while Treatment 5 had the highest NDF intake. Crude protein intake was highest in Treatment 3, and the highest values for most nutrients were observed from the same treatment. The results for nitrogen balance in Yankasa rams indicate a positive nitrogen balance, suggesting that the rams received adequate amounts of nitrogen from the diets fed. Feeding 20% cowpea husk and 20% tiger nut residue provides optimum performance for rams in terms of rumen fermentation, and nutrient utilisation.

Milk somatic cell count affects feed efficiency through increased heat production of lactating dairy cows

The objective was to evaluate the relationships between somatic cell count (SCC) and feed efficiency using the data from two respiration chamber studies using Nordic Red cows (n = 136). The cows were fed ad libitum a total mixed ration (forage: concentrate 45:55 on dry matter (DM) basis) containing 162 and 379 g crude protein and neutral detergent fibre in kg DM, respectively. Average (± SD) DM intake and energy corrected milk (ECM) yield were 23.6 ± 3.4 and 37.7 ± 6.1 kg/d, respectively. Blood samples were collected in one of the studies (n = 86). Feed efficiency was expressed as ECM/DM intake, residual feed intake (RFI) and residual ECM yield (RECM). Feed efficiency decreased significantly with increased SCC irrespective of how the efficiency was expressed. Data from energy metabolism indicated that conversion of dietary gross energy to metabolizable energy (ME) was not influenced by SCC, but the efficiency of ME utilization decreased as a result of increased heat production. Increased heat production might be associated with the greater energy demand for immune function. Blood haptoglobin increased with SCC also indicating the role of immune function in increased heat production. Methane intensity increased by 1.0 g/kg ECM above cut-off value of 47 000 cells/mL. It is concluded that in addition to economic losses and animal welfare issues, increased milk SCC has negative environmental impact.

PSIV-A-5 Effect of roughage inclusion in limit-fed cow rations on behavior, cow hygiene, and manure scores

Abstract The objective was to determine the effects of roughage inclusion in isocaloric total mixed rations (TMR) fed to drylot housed cow-calf pairs on behavior, manure score, and hygiene score. Spring-born Simmental x Angus cows (n = 72) and their calves were stratified by calf age, sex, and body weight (BW) and assigned to 12 pens with 6 pairs to pen. Pens were randomly assigned to one of two treatments: moderate roughage inclusion (40%) TMR targeting DMI of 1.7% of BW (LimitTMR) or high roughage inclusion (60%) TMR targeting DMI of 2.1% of BW (BulkyTMR). Concrete bunks (4.7 m; 0.8 m/cow). Cow-calf pairs were housed in concrete dry lots with open-front buildings. Buildings were bedded with straw once a week. Cow and calf behavior (standing, lying, at bunk, and eating bedding) was observed hourly from 1 h before feeding until 6 h post-feeding. Behavior assessments were done on 2 consecutive days (before new bedding and after new bedding) each week for 5 wk. Hygiene and manure scoring was conducted on d 40 and 75 by 2 trained evaluators. Hygiene was scored on a 1-4 scale; 1 – no manure, 4 confluent plaque of manure. Cow hygiene was evaluated on the lower leg, udder, and upper leg and flank. Manure from each pen was scored on a 1-5 scale; 1 – very liquid consistency, 5 – firm fecal balls. Data were analyzed using the MIXED procedure of SAS 9.4. On day prior to new bedding, there was a treatment × time interaction (P &amp;lt; 0.01) for cows at bunk. More cows on BulkyTMR were at the bunk at h 2, 3, 4, and 5 post-feeding. On day after new bedding, there was also a treatment × time interaction (P &amp;lt; 0.01) for cows at bunk. More cows on LimitTMR were at the bunk before feeding; however, more cows on BulkyTMR were at bunk at h 2 and 3 post-feeding. On both evaluation days there was a treatment × time interaction (P ≤ 0.05) for calves at bunk. More calves on BulkyTMR were at the bunk at h 1 and 2 post-feeding. Cows fed the LimitTMR had dirtier (P ≤ 0.02) lower leg (1.5 vs 1.2) and upper leg/flank (1.4 vs 1.1) hygiene scores on d 40 than cows fed the BulkyTMR; however, there were no treatment differences (P ≥ 0.31) on d 75. There were no treatment differences (P ≥ 0.26) for manure scores on d 40 or d 75. In conclusion, a bulkier TMR with more roughage inclusion resulted in more time at the bunk for cows and calves and cleaner hygiene scores for cows, but roughage inclusion did not affect manure scores.

PSV-1 A comparison of Holstein-cross cattle and beef-cross cattle in terms of performance and carcass quality

Abstract Crossbreeding Holstein cows to beef sires has increased in popularity as a means to increase marketability of the dairy offspring. A large portion of these dairy-cross animals are offspring of Holstein cows and Angus bulls. The objective of this study was to evaluate the carcass quality of 3 crossbred beef steers (Hereford x Angus) and 3 dairy x beef cross steers (Holstein x Angus). These animals had been a part of a previous study evaluating the additive effect of implanting strategy combined with inclusion of a beta-agonist and represent the three different treatments evaluated on that study with one dairy-cross and one beef-cross animal coming from each treatment. All steers were fed a mixed ration consisting of 30.0% rye silage, 28.0% DDGS, 30.0% rolled corn, 10.5% soybean meal, and 1.5% mineral supplement (22.0% CP, 2.90 Mcal ME/kg DM). Animals were fed daily at 0700 and 1700 and weighed weekly at 0630. For the duration of the trial, animals were housed in drylot pens with ad libitum access to feed and water and had shade structures in each pen. Following a 15-d adaptation period, feed intake was recorded for 45 d. Data were analyzed as a completely random design in SAS v9.4. The animals were evaluated in terms of growth and performance, carcass quality, and feed efficiency. There was no difference in intake for either treatment; however, beef-cross steers gained significantly more than their dairy-cross counterpart on the same diet. After the intake portion of the study was completed, all six chosen animals were slaughtered and evaluated for carcass quality. Following 14 d aging, samples from the ribeye area were collected from each animal and subjected to sensory analysis and other assessments of quality. Other than a numerical difference in marbling score between treatments, there were no statistical differences in meat quality between the two crosses indicating that dairy-cross animals are an important addition to the beef industry.

PSV-11 In vitro screening of selected compounds to reduce ruminal methane production

Abstract Methane is a natural product of rumen fermentation and emissions from ruminant livestock represent a major environmental concern. Methane is not only a potent greenhouse gas but also represents a loss of energy efficiency for the host. The objective of this study was to perform in vitro screening of a range of compounds with potential anti-methanogenic activity, including polyphenols, flavonoids, fatty acids, amino acids, and salts. We aimed to select compounds conferring up to a 20% reduction in CH4 for further investigations. The substances tested included carvacrol, coumaric acid, coumarin, flavanone, gallic acid, glycerol monolaurate (GML), glycine, methylene blue, naringin, quercetin, quinic acid, resorcinol, rutin, tannic acid, vanillic acid, and zinc acetate. These substances varied in their mechanisms of action and were selected based on known antimicrobial or anti-methanogenic properties. The experiment was designed as a randomized block experiment, with treatments tested in triplicates across four batches (n = 228 samples) using the same treatments and experimental conditions. Fresh rumen contents were manually collected from two rumen-fistulated lactating Holstein cows, 3 h after their morning feeding. Rumen contents were blended at a 2:1 ratio, filtered through a four-layered cheesecloth, and added to McDougall’s solution at a 2:1 ratio. Final media (9 mL) was added to a 20 mL Bellco flask containing 150 mg of total mixed ration (TMR) ground to 1 mm. Each batch also had three flasks without TMR and no treatment (blank flasks), three flasks containing only TMR without treatment (negative control), and three flasks containing TMR and treated with chloroform (positive control), resulting in a total of 19 treatments. The end-products of in vitro batch fermentations were assessed after 24 h of incubation, and samples from each flask were collected for gas composition analysis using gas chromatography. Volatile fatty acids were determined using high-performance liquid chromatography (HPLC). The data were analyzed using R Studio, and the following model was applied: yij = µ + treatmenti + batchj + ℇij. Methane production (measured in parts per million, ppm) increased when GML, naringin, and quercetin were added compared with the negative control. In contrast, the addition of carvacrol, glycine, tannic acid, and methylene blue resulted in a decrease of up to 25% in methane production. These compounds show potential to alter ruminal fermentation and mitigate methane production and will be selected for evaluation of synergistic interactions and effects on the rumen microbial communities.

PSV-13 The influence of diet type on beef cattle performance and meat quality characteristics

Abstract The objective of this study was to determine what additive effect hormonal implants and inclusion of beta-agonists in the diet have on carcass quality in yearling beef steers. Hereford-cross steers [n = 21; initial body weight (BW) = 450 ± 15 kg] were assigned to one of three drylot pens based on initial BW and sire so that each pen had an equal starting BW and sires were equally represented in each pen. Each drylot pen was assigned to one of three treatments: receiving a hormonal implant (IMP), consuming a beta-agonist (BAG), or receiving both of the previous treatments (AND). All steers were fed a mixed ration consisting of 30.0% rye silage, 28.0% DDGS, 30.0% rolled corn, 10.5% soybean meal, and 1.5% mineral supplement [22.0% CP, 2.90 Mcal ME/kg dry matter (DM)]. Animals were fed daily at 0700 and 1700 h and weighed weekly at 0630 h. For the duration of the trial, animals were housed in drylot pens with ad libitum access to feed and water and had shade structures in each pen. Following a 15-d adaptation period, feed intake was recorded for 45 d. Body weight gain for each treatment group were 1.26, 1.28, and 1.48 kg/d for IMP, BAG, and AND, respectively. Animals on the AND treatment were significantly more feed efficient than the IMP treatment with F:G ratios of 5.9 kg/kg gain and 6.8 kg/kg gain, respectively. After the intake portion of the study was completed, an animal from each pen was slaughtered and evaluated for carcass quality. Hot carcass weights for diets IMP, BAG, and AND were 347.4, 352.9, and 394.8 kg, respectively. Data were analyzed as a completely random design in SAS v9.4. There was not a significant difference between the IMP treatment and the AND treatment based on assessment from Warner-Bratzler shear force, carcass yield, marbling score, and sensory assessment (P &amp;gt; 0.05); however, the BAG treatment had less marbling than the other two treatments. It was concluded that the additive effect of using both a hormonal implant and a beta-agonist can improve feed intake and feedlot performance without detrimental effects on carcass quality.

57 Effect of diet mixing strategies on growth performance and carcass characteristic in feedlot steer

Abstract Our objective was to determine the effects of a feeding management strategy on growth and carcass quality and characteristics on finishing feedlot beef cattle. Angus-Simmental steers (n = 60), blocked by body weight (BW), were housed in individual pens and randomly assigned to treatments. Treatments were total mixed ration (TMR) or a non-mixed diet (Split). The diet contained 67.5% of dry rolled corn, 18% of distiller grains with soluble, 2.5% soybean meal, 7% hay, and 5% of mineral and vitamin mixed. The diet composition for both treatments was similar, the only difference was the use of a TMR or that the concentrate was fed separately from the hay on the Split treated calves. Feed intake was monitored through slick bunk management in both treatments. For the Split assigned calves, if any hay or concentrate was left in the bunk on two consecutive days, the total feed was decreased by 5%; maintaining always the 93% concentrate and 7% forage ratio. Steers were weighed monthly and feed samples were collected for nutrient composition analysis semimonthly. Monthly weights and intakes were used to calculate average daily gain (ADG) and gain to feed ratio (G:F). Steers were slaughtered per block when the average weight of the block reached 555 kg. Carcasses were evaluated 48 h post slaughter. Carcass yield and quality factors were evaluated at the 12th/13th rib interface. Data were analyzed as randomized complete block design. Considering the fixed effect of the feeding strategy and the random effect of block. We did not observe differences (P &amp;gt; 0.17) in growth performance or carcass characteristics variables due to management strategy (Table 1). The lack of observed differences due to treatment might be because the ratio of concentrate and forage intake was similar for both groups, in addition to the slick bunk management in both treatments, which forced steers to eat all their ration, independent of the treatment, to continue to receive the same amount of feed.

104 Effects of providing vitamin and mineral supplementation throughout gestation on subsequent F1 replacement heifer liver and muscle oxygen consumption and mitochondrial function throughout pregnancy

Abstract The study aimed to assess the impact of maternal vitamin/mineral supplementation during gestation on the energy utilization in liver and muscle tissues of F1 heifer offspring. We hypothesized that VTM supplementation during gestation would mitigate mitochondrial energy loss and uncoupling of liver and muscle tissue in pregnant offspring. At breeding, crossbred Angus heifers [n = 31; initial body weight (BW) = 412.5 ± 53.68 kg] were randomly assigned to either a basal diet targeting BW gains of 0.45 kg•heifer-1•d-1(CON; n = 14) or the basal diet plus 113 g•heifer-1•d-1of a vitamin/mineral supplement (VTM; n = 17). Heifers remained on their respective dietary treatments until calving. After calving, all F1 heifer calves were raised in a single management group with their dams until weaning (BW = 209 ± 4.82 kg; VTM, n = 17; CON, n = 12) and fed a common diet throughout postnatal development. At breeding and throughout gestation, F1 heifers (n = 9, VTM; n = 7, CON) were allotted daily feed intakes of 1.5% of BW on a dry-matter basis as a total mixed ration and used to evaluate cellular energy metabolism throughout pregnancy. Liver and Longissimus dorsi muscle biopsies were collected on d 179 and d 247 +/- 3 of gestation and mitochondrial function was assessed via high resolution respirometry (Oroboros Instruments, Innsbruck, Austria). The following respiratory states were evaluated: LEAK respiration (L), OXPHOS capacity (P), NADH-linked OXPHOS (PI), and electron transfer capacity (E). Data were analyzed using the MIXED procedure of SAS with repeated measures where appropriate. No treatment × trimester interaction (P ≥ 0.13) was observed for any of the respiratory states in liver and muscle. Hepatic oxygen consumption was not influenced by maternal gestational VTM supplementation (P ≥ 0.68), or stage of gestation (P ≥ 0.27). In muscle, L respiration was the only state affected by maternal dietary treatments, being greater (P = 0.05) in CON than VTM heifers. Additionally, L respiration was greater (P = 0.02) during the third trimester compared with the second trimester. This observation in CON heifers is important because increased L respiration (proton leak) results in decreased ATP production. Protons that escape the intermembrane space, are dissipated as heat rather than be used for ATP synthesis; thus, oxygen consumption increases to compensate for the reduction of protons entering ATP turnover. Results show increased muscle mitochondria inefficiency in offspring with dams lacking supplementation during pregnancy. The increased incidence of proton leak results in potentially less efficient cattle as protons escape the electron transport chain rather than be transformed for energy utilization need of the animal, thus VTM supplementation throughout pregnancy impacts fetal development with potential effects in live offspring 18 to 22 mo post-parturition.