High-forage Diets Research Articles

Climate Spaces and Cliffs: A Novel Bovine Thermodynamic and Mass Balances Model.

The effects of climate change on animals are typically viewed in terms of survivability and wellbeing. In this study, we broaden that purview to include climate impacts on reproductive capability. There are not only climate spaces for daily function, but climate cliffs that represent reproductive failures in the face of climate warming. This alternative focus suggests that climate warming challenges may be more immediate and profound than initially imagined. This research describes a state-of-the-art mechanistic model, Dairy Niche Mapper (DNM), and independent validation tests. Where test data are absent, the calculated results are consistent with expected responses. Simulations of metabolic chamber conditions reveal the local steady-state impacts of climate and animal variables on milk production capacity, metabolic rate, food consumption and water needs. Simulations of a temperature humidity index (THI) show strengths and limitations of that approach. Broader time- and spatial-scale calculations applied in the western and eastern halves of the northern hemisphere identify current and future monthly latitudinal climate change impacts on milk production potential, feed and water needs in dairy cows of different sizes. Dairy Niche Mapper (DNM) was developed from a broadly tested mechanistic microclimate-animal model, Niche Mapper (NM). DNM provides an improved quantitative understanding of the complex nonlinear interactions of climate variation and dairy bovine properties' effects on current and future milk production, feed and water needs for grazing and confinement dairy operations. DNM outputs include feasible activity times, milk production and water and feed needs of different-sized Holstein cows on high-grain (confinement feeding) versus high-forage (grazing feeding) diets at three arbitrary north latitudes, 12°, 30° and 60°, for North and Central America and for Asia. These three latitudes encompass current northern hemisphere bovine production environments and possible future production locations. The greatest impacts of climate change will be in the low elevations in tropical and subtropical regions. Global regions above 30° and below 60° latitude with reliable rainfall will be least affected by current projected levels of climate change. This work provides the basis for computational animal design for guiding agricultural development via breeding programs, genetic engineering, management options including siting or the manipulation of other relevant environmental and animal variables.

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

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

Supplementing branched-chain volatile fatty acids in dual-flow cultures varying in dietary forage and corn oil concentrations. III: Protein metabolism and incorporation into bacterial protein

Some cellulolytic bacteria cannot transport branched-chain AA (BCAA) and do not express complete synthesis pathways, thus depending on cross-feeding for branched-chain volatile fatty acid (BCVFA) precursors for membrane lipids or for reductive carboxylation to BCAA. Our objective was to assess BCVFA uptake for BCAA synthesis in continuous cultures administered high forage (HF) and low forage (LF) diets without or with corn oil (CO). We hypothesized that BCVFA would be used for BCAA synthesis more in the HF than in LF diets. To help overcome bacterial inhibition by polyunsaturated fatty acids in CO, BCVFA usage for bacterial BCAA synthesis was hypothesized to decrease when CO was added to HF diets. The study was an incomplete block design with 8 dual-flow fermenters used in 4 periods with 8 treatments (n = 4) arranged as a 2 × 2 × 2 factorial. The factors were: HF or LF (67 or 33% forage, 33:67 alfalfa:orchardgrass pellets), without or with supplemental CO (3% of dry matter), and without or with 2.15 mmol/d (5 mg/d 13C) each of isovalerate, isobutyrate, and 2-methylbutyrate for one combined BCVFA treatment. The flow of bacterial BCAA increased by 10.7% by supplementing BCVFA and 9.14% with LF versus HF; similarly, dosing BCVFA versus without BCVFA increased BCAA by 1.98% in total bacterial AA, whereas LF increased BCAA by 1.92% versus HF. Additionally, BCVFA supplementation increased bacterial AA flow by 16.6% when supplemented in HF - CO and 12.4% in LF + CO diets, but not in the HF + CO (-1.5%) or LF - CO (+6.7%) diets (Diet × CO × BCVFA interaction). The recovery of 13C in bacterial AA flow was 31% lower with LF than with HF. Of the total 13C recovered in bacteria, 13.8, 17.3, and 30.2% were recovered in Val, Ile, and Leu, respectively; negligible 13C was recovered in other AA. When fermenters were dosed with BCVFA, nonbacterial and total effluent flows of AA, particularly of alanine and proline, suggest decreased peptidolysis. Increased ruminal outflow of bacterial AA, especially BCAA, but also nonbacterial AA could potentially support postabsorptive responses from BCVFA supplementation to dairy cattle.

Evaluation of different ensiling methods for Saccharina latissima preservation: influence on chemical composition and in vitro ruminal fermentation

ABSTRACT Saccharina latissima is a brown seaweed that could be used in ruminant feeding, but its fast deteriorating and seasonal growth nature limit their utilisation in the practice. Ensiling could be used as a preservation method, but information of its effects on the nutritional value of the seaweed is limited. This study evaluated the in vitro ruminal fermentation of different S. latissima silages using ruminal inoculum either from goats fed a mixed diet (60:40 oat hay:concentrate) or from sheep fed a high-forage diet (90:10 alfalfa hay:concentrate) to simulate different small ruminant production systems. S. latissima was ensiled in vacuum bags without additives (Control), with formic acid (4 g/kg seaweed; FA), with lactic acid bacteria (LAB) or with LAB after a pre-wilting treatment to reach a seaweed dry matter (DM) content of 30% (30LAB). Ensiling S. latissima decreased (p < 0.05) the content in DM, neutral detergent fibre and total extractable polyphenols, but nitrogen and fat content were unaffected. For both ruminal inoculums, ensiling decreased (p < 0.05) the asymptotic gas production after 120 h of fermentation (excepting for FA silage with goats’ inoculum), but the total volatile fatty acid (VFA) production was unaffected. The VFA profile shifted towards greater (p < 0.05) acetate and lower (p < 0.05) propionate proportions in all silages compared with the pre-ensiling S. latissima. When goats inoculum was used, greater (p < 0.05) CH4 production compared with pre-ensiling S. latissima was observed in all silages, except Control one, which led to greater (p < 0.05) CH4/total VFA ratio. In contrast, no differences among samples (p > 0.05) in either CH4 production or CH4/total VFA ratio were observed when sheep’ inoculum was used. Fermentation of all samples started earlier with goats’ inoculum than with sheep’ inoculum, which was attributed to the different diet fed to the animals. These results suggest that ensiling S. latissima with either formic acid or lactic acid bacteria could be a viable conservation method to preserve the nutritive value.

O46 (not presented) Effect of different supplementation levels of Cymbopogon citratus on methane emissions from growing beef cattle fed a high-forage diet

O46 (not presented) Effect of different supplementation levels of Cymbopogon citratus on methane emissions from growing beef cattle fed a high-forage diet

16S rRNA Sequencing Reveals the Antibacterial Effect of Omega-3 (Fish Oil) against Fibrolytic Bacteria, Altering Fermentation and Volatile Fatty Acids Profile In Vitro

Polyunsaturated fatty acids (PUFAs) constitute a significant lipid class with essential nutritional and health benefits for both animal and human health; however, their effect and interaction with the gut microbiota ecosystem are still unclear. Therefore, the present study aims to investigate the effect of fish oil (FO) on ruminal fermentation and bacterial abundance under high- and low-forage diets. Thirty-six ruminal fluid samples were allocated into two experiments. The first was on high-forage diet and included three groups: the control (basal diet with 70% forage and 30% concentrate), group 2 (basal diet + 5 mL/L FO), and group 3 (basal diet + 10 mL/L). The second experiment was on low-forage diet: the control (basal diet with 30% forage and 70% concentrate), group 2 (basal diet + 5 mL/L FO), and group 3 (basal diet + 10 mL/L). The results showed that although FO supplementation did not affect the pH level among different diets, it significantly decreased methane under a high-forage diet. In addition, regarding the fatty acids profile, FO supplementation in high-forage diet significantly decreased fatty acids in both; however, under a low-forage diet, FO groups showed significantly higher fatty acid content than the control. However, FO supplementation increased the abundance of Anaerovibirio, Selenomonas, pseudobutyrivibrio, and butyrivibrio through a high-forage diet. In contrast, the abundance of Prevotella, Rikenellaceae RC9 gut group, and Saccharofermentans was depressed with FO supplementation. Whereas under low-forage diet, FO supplementation increased Ruminobacter, Anaerovibirio, Megasphaera, Pseudobutyrivibrio, Streptococcus, Butyrivibrio, unclassified_lachnospiraceae; it also decreased Prevotella and Rikenellaceae RC9 abundance similar to the high-forage diet. Based on the KEGG pathway results, FO supplementation significantly downregulated genes mainly related to folding, sorting and degradation, environmental adaptation, cell motility, transcription, membrane transport, and signal transduction. The results revealed that FO has a depressing effect on ruminal fermentation and some bacterial population; however, this negative effect can be minimized in high-concentrate diets.

Rumen microbiome response to sustained release mineral bolus supplement with low- and high-quality forages

IntroductionLimited forage quantity and quality are challenges faced in livestock production systems in semi-arid rangelands of the western United States, particularly when livestock face stressors such as cold weather or have increased nutritional requirements such as during pregnancy and lactation. To meet livestock nutrient requirements, producers frequently provide supplemental nutrition, however there is limited knowledge regarding the effects of these practices on the rumen microbiome in these environments.MethodsA study was conducted to evaluate changes in the rumen microbiome in response to high- and low- quality forage with sustained release mineral boluses. The study consisted of 16 ruminally-cannulated 2–3-year-old black angus cows fed high quality grass alfalfa hay or low-quality grass hay with a 90 or 180 day sustained release mineral bolus. Rumen samples were collected pre-feeding and 8 hours post feeding and bacterial 16S rRNA gene amplicons were sequenced from the rumen fluid.ResultsAlpha diversity as measured by Shannon’s diversity index decreased significantly over time (p&amp;lt;0.01) and averaged 5.6 pre-feeding and 5.4 post- feeding and was not significantly different between high- and low-quality forages or between mineral bolus types (p&amp;gt;0.05). Principal coordinates analysis (PCoA) of the Bray-Curtis dissimilarity matrix showed distinct grouping by feed quality and time but not by mineral bolus type. Bacteroidetes and Firmicutes were the dominant phyla in all treatments and significant increases (p&amp;lt;0.05) in the relative abundance of the family Lachnospiraceae and the genus Prevotella were observed in high quality forage diets. Rumen VFA and NH3-N concentrations were also strongly associated with the high-quality forage diet. Predictive functional profiling indicated that functions associated with methanogenesis were negatively correlated with feed quality.DiscussionThe results of this study suggest that mineral bolus type is unlikely to affect rumen bacterial community structure or function while forage quality can significantly alter community structure and predicted functions associated with methanogenesis and VFA production.

Evaluation of the red seaweed Mazzaella japonica as a feed additive for beef cattle

Supplementing ruminant diets with macroalgae is gaining interest globally because bromoform-containing seaweeds (e.g., Asparagopsis spp.) have been shown to be highly effective enteric methane (CH4) inhibitors. Some alternative seaweeds decrease in vitro CH4 production, but few have been evaluated in animals. This study examined the effects of including the red seaweed Mazzaella japonica in the diet of beef cattle on dry matter intake (DMI), rumen fermentation, digestibility, nitrogen (N) utilization, and enteric CH4 production. Six ruminally cannulated, mature beef heifers (824 ± 47.1 kg) were used in a double 3 × 3 Latin square with 35-d periods. The basal diet consisted of 52% barley silage, 44% barley straw, and 4% vitamin and mineral supplement [dry matter (DM) basis]. The treatments were (DM basis): 0% (control), 1%, and 2% M. japonica. The DMI increased quadratically (P = 0.025) with the inclusion of M. japonica, such that the DMI of heifers consuming 1% was greater (P &amp;lt; 0.05) than that of control heifers. The apparent total-tract digestibility of DM decreased linearly (P = 0.002) with the inclusion of M. japonica, but there were no treatment differences in the digestibility of organic matter, crude protein (CP), neutral detergent fiber, or starch. The level of M. japonica linearly (P &amp;lt; 0.001) increased the N intake of the heifers. Fecal N excretion linearly increased (P = 0.020) with M. japonica, but there were no differences in total urinary N excretion, N fractions (allantoin, uric acid), total purine derivatives, microbial purine derivatives absorbed, microbial N flow, or retained N. There were no treatment effects on rumen pH or total volatile fatty acids (VFAs); however, adding M. japonica to the diet quadratically (P = 0.023) decreased the proportion of acetate, whereas 1% inclusion decreased the acetate proportion. Methane production (g/day) decreased quadratically (P = 0.037), such that the heifers receiving 2% M. japonica produced 9.2% less CH4 than control animals; however, CH4 yield (g/kg DMI) did not differ among treatments. We conclude that supplementing a forage-based diet with up to 2% M. japonica failed to lower the enteric CH4 yield of beef heifers. M. japonica can be used in diets to help meet the CP requirements of cattle, but inclusion rates may be limited by high inorganic matter proportions. When comprising up to 2% of the diet, M. japonica cannot be recommended as a CH4 inhibitor for beef cattle fed on high-forage diets.

Grass finishing of Criollo cattle can provide an environmentally preferred and cost effective meat supply chain from United States drylands

CONTEXTThe southwestern United States is experiencing an increasingly warmer and drier climate that is affecting cattle production systems of the region. Adaptation strategies are needed that will not compromise environmental quality or profitability. Options include the use of desert-adapted beef cattle biotypes, such as Rarámuri Criollo cattle, and crossbreds of Criollo with more traditional British breeds. Currently, most calves raised in the Southwest are grain finished, often with irrigated crops produced in the hydrologically-threatened Ogallala Aquifer region. A viable alternative may be grass finishing with the rainfed forage of the arid and semi-arid rangeland of the Southwest or in the temperate grasslands of the Northern Plains. OBJECTIVECompare the environmental impacts and production costs of grain-finishing in Texas and grass-finishing in the Northern plains and the Southwest with traditional Angus cattle vs. Criollo and Criollo x Angus cattle. METHODSNine supply chain strategies were simulated using the Integrated Farm System Model to compare farm-gate life cycle intensities of greenhouse gas emissions (carbon footprint), fossil energy footprint, nitrogen footprint, blue water footprint and production costs using representative (appropriate soils, climate, and management) ranch and feedlot operations. RESULTS AND CONCLUSIONSFor both finishing options (grass, grain), Criollo x Angus cattle had the best environmental (3%–27% lower), and production cost (4–23% lower) outcomes followed by pure Criollo and then Angus cattle. Crossbred production combined the lower feed supplementation requirements of Criollo cows with heavier final carcasses of offspring from Angus genetics. Crossbred cattle with grass finishing in the Southwest or Northern Plains outperformed on most environmental variables as well as production costs, mostly due to reduced external input requirements (primarily feed). A downside for grass-finished crossbreds was greater carbon footprint (27–42% higher) compared to grain finishing due to greater methane emissions from high forage diets and an extended time to finish. On grasslands where soil C sequestration can be supported, that land-based sequestration may offset the greater greenhouse gas emission from enteric methane of grass-finished beef. Grass finishing in the Northern Plains may provide a more reliable meat supply chain than grass finishing in the Southwest due to the lower risk and less severe consequences of drought. SIGNIFICANCEAlternative beef supply chain options using Rarámuri Criollo cattle were found to be sustainable production systems that can be adopted by ranchers in the southwestern United States to adapt to the changing climate.

8 Differential Growth Performance in Conventionally and Artificially Raised Lambs Fed High-Concentrate and High-Forage Post-Weaning Diets

Abstract Artificial rearing of lambs on milk replacer presents management challenges for producers and can impact performance. The objective of this experiment was to evaluate effects of pre-weaning management on adaptation to post-weaning finishing diets. We hypothesized that lambs fed a high-concentrate (HC) diet would exhibit more efficient body weight (BW) gain than lambs fed a high-forage diet (HF) regardless of pre-weaning management. Thirty-two Polypay conventionally raised (CR; n = 10 rams, 6 ewes) or artificially raised (AR; n =10 rams, 6 ewes) lambs (age: 84.0 ± 0.8 d) were blocked by sex and BW and randomly assigned to either a HC (85:15 concentrate: forage) or HF (50:50 concentrate:forage) finishing diet (n = 8 CR and AR lambs diet-1). Individually housed lambs were fed ad libitum and remained on feed through a target finishing weight of 59.0 or 54.4 kg for rams and ewes, respectively. Feed intake and BW gain were measured at 7-day intervals. Data were analyzed by PROC GLM in SAS (v. 9.4, SAS Inst. Inc., Cary, NC). Initial BW for CR lambs (39.0 ±.9 kg) was greater than for AR (32.9 ± 0.5 kg; P &amp;lt; 0.01), but there was no difference between diets (P = 0.72) or pre-weaning by diet interaction (P = 0.54). Time on feed and average daily gain (ADG) did not differ between diets for CR (time on feed: 48.1 ± 2.8 d; ADG: 206.9 ±1.4 g∙d-1; P ≥ 0.22). In contrast, post-weaning diet did impact time on feed for AR lambs, with longer time on feed for HF (68.9 ± 2.5 d) than HC (56.2 ± 2.4 d; P &amp;lt; 0.01). The ADG was also numerically greater for HC (424 ±9.8 g) than HF (370 ± 24.0 g) for AR lambs (P = 0.11). Dry matter intake (DMI) was less for CR lambs fed HC (35.16 ±.65 g kg BW-1∙d-1) than HF (41.32 ± 0.69 g∙kg BW-1∙d-1,P &amp;lt; 0.01) but did not differ between diets for AR lambs (40.58 ±.35 g kg BW-1∙d-1; P = 0.99). The decreased DMI in CR lambs fed HC resulted in greater feed efficiency (0.26 ± 0.02) compared with lambs fed HF (0.21 ± 0.01; P = 0.03). Feed efficiency did not, however, differ by diet for AR lambs (HC: 0.27 ± 0.02; P = 0.64). Results of this study suggest that CR lambs were better able to adapt to a HF finishing diet than AR lambs. Additionally, CR lambs exhibited superior feed utilization when fed HC in comparison to HF, but this response was not found for AR lambs. Overall, these results demonstrate differential adaptation to HC vs. HF finishing diets in response to pre-weaning management.

Effects of the addition of non-fibre carbohydrates with different rumen degradation rates in dairy cow high-forage diets using the Rumen Simulation Technique.

Nutrient synchronisation of protein and carbohydrates is a promising practice to improve ruminal nutrient utilisation. However, dietary sources supplying these nutrients can vary in ruminal nutrient availability due to differing degradation rates, therefore potentially affecting utilisation of nitrogen (N). The effects of the addition of non-fibre carbohydrates (NFCs) with different rumen degradation rates in high-forage diets on ruminal fermentation, efficiency and microbial flow were investigated in vitro using the Rumen Simulation Technique (RUSITEC). Four diets were tested: control with 100% ryegrass silage (GRS) and substitution of 20% on a DM basis of ryegrass silage with corn grain (CORN), processed corn (OZ) or sucrose (SUC). The four diets were assigned to 16 vessels in two sets of RUSITEC apparatuses in a randomised block design over a 17 d experimental trial; 10 d consisted of adaptation and 7 d for sample collection. Rumen fluid was collected from four rumen-cannulated dry Holstein-Friesian dairy cows and was treated without mixing. Then, rumen fluid from each cow was used to inoculate four vessels, and diet treatments were randomly allocated to each one. This was repeated for all cows resulting in 16 vessels. The inclusion of SUC in ryegrass silage diets improved DM and organic matter digestibility. The only diet to significantly lower ammonia-N concentration compared with GRS was SUC. The outflows of non-ammonia-N, microbial-N, and efficiency of microbial protein synthesis were not affected by diet type. However, the efficiency of nitrogen utilisation was improved by SUC compared with GRS. This indicates that the inclusion of an energy source with a high rumen degradation rate in high-forage diets improves rumen fermentation, digestibility, and N utilisation. Specifically, this effect was observed for the more readily available energy source, SUC, compared with the more slowly degradable NFC sources, CORN and OZ.

Differential Diet and pH Effects on Ruminal Microbiota, Fermentation Pattern and Fatty Acid Hydrogenation in RUSITEC Continuous Cultures

The aim of this study was to distinguish effects due to diet composition from those triggered by ruminal pH on fermentation patterns and microbial profiles in a continuous culture system (RUSITEC). The study followed a 2 × 2 factorial design, with two diets varying in the proportions of forage and concentrate and two pH levels in the culture medium. RUSITEC fermenters were used to simulate rumen fermentation and feed digestibility, fermentation end-products, microbial protein synthesis, microbial community, and long-chain fatty acid profiles in the digesta were determined. Multivariate analyses were applied to summarize the overall results. High concentrate (34% cereal grain, 32% hay) diets were more digestible (p &lt; 0.05) than high forage (10% cereal grain, 78% hay) diets, resulting in a greater (p &lt; 0.05) formation of most fermentation end-products and microbial protein in the rumen. However, there were no significant (p &gt; 0.05) differences between diets in methane production. Ciliate protozoa, anaerobic fungi, some fibrolytic bacteria, hydrogenation of oleic acid, and relative proportion of conjugated linoleic acid were increased (p &lt; 0.05) with high forage diets. A decline in rumen pH from 6.8 to 6.4 decreased (p &lt; 0.05) feed digestibility, protein degradability, and the daily outputs of some fermentation end-products (gas, VFA, acetate, ammonia) but had no effect (p &gt; 0.05) on the synthesis of microbial protein, and on the output of methane, propionate, butyrate or lactate. Minor changes in microbial community profile or the fatty acid relative proportions were observed within this pH range. The overall multivariate analysis revealed a clear discrimination between high-concentrate and high-forage diets, with subtler and less-defined pH effects on ruminal fermentation and microbial communities.

Blood and milk metabolites of Holstein dairy cattle for the development of objective indicators of a subacute ruminal acidosis.

The purpose of this study was to perform a comparative analysis of metabolite levels in serum and milk obtained from cows fed on different concentrate to forage feed ratios. Eight lactating Holstein cows were divided into two groups: a high forage ratio diet (HF; 80% Italian ryegrass and 20% concentrate of daily intake of dry matter) group and a high concentrate diet (HC; 20% Italian ryegrass and 80% concentrate) group. Blood was collected from the jugular vein, and milk was sampled using a milking machine. Metabolite levels in serum and milk were estimated using proton nuclear magnetic resonance and subjected to qualitative and quantitative analyses performed using Chenomx 8.4. For statistical analysis, Student's t-test and multivariate analysis were performed using Metaboanalyst 4.0. In the principal component analysis, a clear distinction between the two groups regarding milk metabolites while serum metabolites were shown in similar. In serum, 95 metabolites were identified, and 13 metabolites (include leucine, lactulose, glucose, betaine, etc.) showed significant differences between the two groups. In milk, 122 metabolites were identified, and 20 metabolites (include urea, carnitine, acetate, butyrate, arabinitol, etc.) showed significant differences. Our results show that different concentrate to forage feed ratios impact the metabolite levels in the serum and milk of lactating Holstein cows. A higher number of metabolites in milk, including those associated with milk fat synthesis and the presence of Escherichia coli in the rumen, differed between the two groups compared to that in the serum. The results of this study provide a useful insight into the metabolites associated with different concentrate to forge feed ratios in cows and may aid in the search for potential biomarkers for subacute ruminal acidosis.

Feeding Management Strategies to Mitigate Methane and Improve Production Efficiency in Feedlot Cattle

Mitigation of greenhouse gases and decreasing nutrient excretion have become increasingly important goals for the beef cattle industry. Because feed intake is a major driver of enteric CH4 production and nutrient excretion, feeding management systems could be important mitigation tools. Programmed feeding uses net energy equations to determine the feed required to yield a specific rate of gain, whereas restricted feeding typically involves decreasing intake relative to the expected or observed ad libitum intake. In the context of growing/finishing systems typical of those in the United States and Western Canada, experimental results with programmed and restricted feeding have often shown decreased overall feed intake and increased gain efficiency relative to ad libitum feeding, but too much restriction can negatively affect harvest weight and associated carcass quality. Slick feed bunk management is a time-based restriction that limits day-to-day variation in feed deliveries, but the effects on intake and performance are not well defined. Simulations to estimate enteric CH4 emission and nitrogen excretion indicated that programmed feeding of a high-grain diet could appreciably decrease CH4 emissions and nitrogen excretion compared with traditional growing programs based on high-forage diets. For feedlot finishing, programming gain for a portion of the feeding period will decrease CH4 emission and N excretion only if cattle perform better than expected during the programmed phase or if compensatory growth occurs when cattle are transitioned to ad libitum feeding. Optimal approaches to implement programmed or restricted feeding that will yield increased efficiency should be the subject of future research in this area.

Effects of soybean oil plus additional forage and anabolic implant in finishing steers: feedlot performance, carcass composition, and meat quality

One hundred twenty crossbred steers were allotted to six weight blocks. Within each block, steers were allotted to one of four pens in a randomized complete block design (5 head per pen, 24 total pens). Treatments were low forage control diets (LFC) or high forage diets supplemented with soybean oil (HFO), without or with anabolic implant in 2 × 2 factorial arrangement. As compared with LFC, HFO reduced dry matter intake and average daily gain, without affecting the gain:feed ratio. Feeding HFO also decreased dressing yield and backfat thickness, with no impact on the longissimus dorsi area and Warner-Bratzler shear force. Meat from steers fed HFO contained greater relative proportion of cis-9, cis-12 18:2, cis-9, trans-11 18:2, and cis-9, cis-12, cis-15 18:3 as compared with LFC. Implanted steers had greater dry matter intake, average daily gain, and gain:feed ratio. Implants improved dressing yield, tended to increase the longissimus dorsi area, decreased backfat thickness, and increased meat Warner-Bratzler shear force. Meat from implanted steers contained greater relative concentration of cis-9, cis-12 18:2 and cis-9, cis-12, cis-15 18:3, without affecting cis-9, trans-11 18:2, as compared with non-implanted animals. No interaction of diet by implant was observed for these variables.

Effects of diet and castration on fatty acid composition and volatile compounds in the meat of Korean native black goats.

This study determined the effects of dietary treatments and castration on meat quality, fatty acids (FAs) profiles, and volatile compounds in Korean native black goats (KNBG, Capra hircus coreanae), including the relationship between the population of rumen microbiomes and meat FA profiles. Twenty-four KNBG (48.6±1.4 kg) were randomly allocated to one of four treatments arranged into a 2×2 factorial structure. The factors were dietary forage to concentrate ratio (high forage [HF, 80:20] and low forage [LF, 20:80]), and a castration treatment (castration [CA] vs non-castration [NCA]). Among meat quality traits, the CA group exhibited a higher percentage of crude fat and water holding capacity (p<0.05). The profiles of the saturated fatty acid (SFA) in meat sample derived from CA KNBG showed a significantly lower percentage compared to NCA individuals, due to the lower proportion of C14:0 and C18:0. Feeding a high-forage diet to KNBG increased the formation of C18:1n7, C18:3n3, C20:1n9, C22:4n6 in meat, and polyunsaturated fatty acid (PUFA) profiles (p<0.05). Consequently, the n6:n3 ratio declined (p<0.05). There was an interaction between dietary treatment and castration for formation of C20:5n3 (p<0.05), while C18:1n9, C22:6n3, monounsaturated fatty acid (MUFA) and the MUFA:SFA ratio were influenced by both diet and castration (p<0.05). Nine volatile compounds were identified and were strongly influenced by both dietary treatments, castration (p<0.05), and their interaction. In addition, principal component analysis (PCA) revealed distinctly different odor patterns in the NCA goats fed LF diets. Spearman correlation analysis showed a high correlation between rumen bacteria and meat PUFAs. These results suggest the essential effects of the rumen microbial population for the synthesis of meat FAs and volatile compounds in KNBG meat, where dietary intake and castration also contribute substantially.

The Effects of Long-term Molybdenum Exposure in Drinking Water on Molybdenum Metabolism and Production Performance of Beef Cattle Consuming a High Forage Diet

Fifty-four multiparous beef cows with calves were used to evaluate the effects of Mo source (feed or water) on reproduction, mineral status, and performance over two cow-calf production cycles (553 days). Cows were stratified by age, body weight, liver Cu, and Mo status and were then randomly assigned to one of six treatment groups. Treatments were (1) negative control (NC; basal diet with no supplemental Mo or Cu), (2) positive control (NC + Cu; 3 mg of supplemental Cu/kg DM), (3) NC + 500 µg Mo/L from Na2MoO4·2H2O supplied in drinking water, (4) NC + 1000 µg Mo/L of Na2MoO4·2H2O supplied in drinking water, (5) NC + Mo 1000-water + 3 mg of supplemental Cu/kg DM, and (6) NC + 3.0 mg of supplemental Mo/kg diet DM from Na2MoO4·2H2O. Animals were allowed ad libitum access to both harvested grass hay (DM basis: 6.6% crude protein; 0.15% S, 6.7 mg Cu/kg, 2.4 mg Mo/kg) and water throughout the experiment. Calves were weaned at approximately 6 months of age each year. Dietary Cu concentration below 10.0 mg Cu/kg DM total diet reduced liver and plasma Cu concentrations to values indicative of a marginal Cu deficiency in beef cows. However, no production parameters measured in this experiment were affected by treatment. Results suggest that Mo supplemented in water or feed at the concentrations used in this experiment had minimal impact on Cu status and overall performance.

3-Nitrooxypropanol supplementation of a forage diet decreased enteric methane emissions from beef cattle without affecting feed intake and apparent total-tract digestibility.

Supplementation of ruminant diets with the methane (CH4) inhibitor 3-nitrooxypropanol (3-NOP; DSM Nutritional Products, Switzerland) is a promising greenhouse gas mitigation strategy. However, most studies have used high grain or mixed forage-concentrate diets. The objective of this study was to evaluate the effects of supplementing a high-forage diet (90% forage DM basis) with 3-NOP on dry matter (DM) intake, rumen fermentation and microbial community, salivary secretion, enteric gas emissions, and apparent total-tract nutrient digestibility. Eight ruminally cannulated beef heifers (average initial body weight (BW) ± SD, 515 ± 40.5 kg) were randomly allocated to two treatments in a crossover design with 49-d periods. Dietary treatments were: 1) control (no 3-NOP supplementation); and 2) 3-NOP (control + 150 mg 3-NOP/kg DM). After a 16-d diet adaption, DM intake was recorded daily. Rumen contents were collected on days 17 and 28 for volatile fatty acid (VFA) analysis, whereas ruminal pH was continuously monitored from days 20 to 28. Eating and resting saliva production were measured on days 20 and 31, respectively. Diet digestibility was measured on days 38-42 by the total collection of feces, while enteric gas emissions were measured in chambers on days 46-49. Data were analyzed using the mixed procedure of SAS. Dry matter intake and apparent total-tract digestibility of nutrients (DM, neutral and acid detergent fiber, starch, and crude protein) were similar between treatments (P ≥ 0.15). No effect was observed on eating and resting saliva production. Relative abundance of the predominant bacterial taxa and rumen methanogen community was not affected by 3-NOP supplementation but rather by rumen digesta phase and sampling hour (P ≤ 0.01). Total VFA concentration was lower (P = 0.004) following 3-NOP supplementation. Furthermore, the reduction in acetate and increase in propionate molar proportions for 3-NOP lowered (P < 0.001) the acetate to propionate ratio by 18.9% as compared with control (4.1). Mean pH was 0.21 units lower (P < 0.001) for control than 3-NOP (6.43). Furthermore, CH4 emission (g/d) and yield (g/kg DMI) were 22.4 and 22.0% smaller (P < 0.001), respectively, for 3-NOP relative to control. Overall, the results indicate that enteric CH4 emissions were decreased by more than 20% with 3-NOP supplementation of a forage diet without affecting DM intake, predominant rumen microbial community, and apparent total-tract nutrients digestibility.

Predicting fecal composition, intake, and nutrient digestibility in beef cattle consuming high forage diets using near infrared spectroscopy.

The objective of this study was to develop near infrared spectroscopy (NIRS) calibrations to predict fecal nutrient composition, intake, and diet digestibility from beef cattle fed high forage diets. Heifers were fed 12 different forage-based diets (>95% forage dry matter basis) in 3 total collection digestibility studies, resulting in individual fecal samples and related spectra (n = 135), corresponding nutrient intake, and apparent total tract digestibility (aTTD) data. Fecal samples were also collected from steers grazing two annual and two perennial forage mixtures over two growing seasons. Samples (n = 13/paddock) were composited by paddock resulting in 30 samples from year 1, and 24 from year 2. The grazing fecal spectra (n = 54) were added to the existing fecal composition spectral library. Dried and ground fecal samples were scanned using a FOSS DS2500 scanning monochromator (FOSS, Eden Prairie, MN). Spectra were mathematically treated for detrend and scatter correction and modified partial least squares (MPLS) regression was performed. The coefficient of determination for cross validation (R2cv) and standard error of cross validation (SECV) were used to evaluate the quality of calibrations. Prediction equations were developed for fecal composition [organic matter (OM), nitrogen (N), amylase-treated ash-corrected neutral detergent fiber (aNDFom), acid detergent fiber (ADF), acid detergent lignin (ADL), undigestible NDF after 240 h of in vitro incubation (uNDF), calcium (Ca), and phosphorus (P)], digestibility [DM, OM, aNDFom, N], and intake [DM, OM, aNDFom, N, uNDF]. The calibrations for fecal OM, N, aNDFom, ADF, ADL, uNDF, Ca, P resulted in R2cv between 0.86 and 0.97 and SECV of 1.88, 0.07, 1.70, 1.10, 0.61, 2.00, 0.18, and 0.06, respectively. Equations predicting intake of DM, OM, N, aNDFom, ADL, and uNDF resulted in R2cv values between 0.59 and 0.91, SECV values of 1.12, 1.10, 0.02, 0.69, 0.06, 0.24 kg·d-1, respectively, and SECV values between 0.00 and 0.16 when expressed as % body weight (BW). Digestibility calibrations for DM, OM, aNDFom, and N resulted in R2cv ranging from 0.65 to 0.74 and SECV values from 2.20 to 2.82. We confirm the potential of NIRS to predict fecal chemical composition, digestibility, and intake of cattle fed high forage diets. Future steps include validation of the intake calibration equations for grazing cattle using forage internal marker and modelling energetics of grazing growth performance.

GPS-derived foraging behaviour of red deer and liveweight gain of red deer and wapiti crossbred sire lines on contrasting winter forage types

Context It is common practice to manage red deer on highly digestible easily harvested forage during winter on New Zealand deer farms, particularly in areas that experience low or no pasture growth during this period. However, not all individuals within these production systems perform equally. Aims To investigate foraging behaviour of young red deer and liveweight gain of young red deer and wapiti crossbred sire lines when offered two contrasting winter forage diets. Methods One hundred and sixty-three rising 1-year-old female red deer and red deer wapiti crossbreds representing five red deer and two wapiti sires, were split into two management groups balanced by sire and liveweight and managed on either an easily harvested highly digestible diet (forage kale) or a harder-to-harvest more poorly digestible diet (pasture) for a 6-week period during winter. Foraging behaviour was monitored on 95 red deer yearlings by using GPS collars over a 2-week period. Liveweights were recorded at the start and end of the 6-week period. Key results Progeny managed on the kale treatment exhibited an extended activity period during the dawn period and a suppressed activity period during the middle of the day. Progeny managed on the pasture treatment exhibited frequent shorter activity periods from dawn to dusk. Time spent foraging and the number of foraging bouts greater than 5 min in duration were different among progeny of different sires. These differences in behaviour did not affect liveweight gain. Liveweight gain over the 6-week trial period was significantly higher for progeny from one wapiti sire than for all red deer sire progeny while being managed on the kale diet (P &lt; 0.001), but there were no differences among progeny on the pasture diet. Conclusion Foraging behaviour varied considerably between sire lines and appeared to vary between forage type, but there were no correlations between behaviour and liveweight gain in this trial. Implications Forage type offered to young red deer may alter their foraging behaviour. Offering an easier to harvest high digestible forage diet may increase liveweight gain of progeny that have a higher genetic potential to grow during the winter period.