Level Of Concentrate Feeding Research Articles

IMPACTS OF CONCENTRATE FEEDING LEVEL WITH OR WITHOUT N-CARBAMYLGLUTAMATE ON PRODUCTIVE PERFORMANCE OF GOATS

This study was conducted to evaluate the effect of feeding three levels of concentrate 2%, 3%, and 4% with or without additives of N-carbamylglutamate (NCG) on the digestibility, feed efficiency, and daily gain of Shami goats. Twenty-four male goats were used aged 8-10 months with an initial weight 32.687 ± 1.52kg divided into six treatments in a 2×3 factorial experiment/ Completely Randomized Design. Individual feeding was used for 70 days preceded by 14 days as an adaptation period. The results of increasing concentrate showed a non-significant increase in nutrients intake with superiority of NCG treatments and a significant increase (P<0.01) of ether extract intake. Non-significant increase in digestibility with increasing feed intake. Significant increases (P<0.01) in total and daily gain of 3% concentrate with or without NCG and non-significant increases for final weight. The better feed efficiency with 3% concentrate then 2% and 4% respectively. In conclusion: A level of feeding 3% had a positive effect on animal performance and the best for fattening.

Relationship between concentrate feeding strategy and grassland phytodiversity on dairy farms

Permanent grassland provides various ecosystem services ranging from livestock feed provision to biodiversity preservation. With increased use of concentrate supplementation in dairy cow rations the importance of permanent grassland as the main feed resource in dairy production systems has decreased, although in Germany a large area of permanent grassland is still utilized by dairy farmers. How phytodiversity can be improved by adaptations at the production-system level other than by organic farming has rarely been examined. We hypothesize that in systems based on lower levels of concentrate feed supplementation farmers adjust their management to the different conditions of grassland sites in interaction with the distinct nutritional needs of the different animal groups in a more differentiated way. Thus, due to higher management diversity, a higher farm-level phytodiversity should be found on those farms. We examined the effect of feeding strategy (low level (LC) vs. typical regional concentrate feeding level (HC)) considering two types of farming systems (organic vs. conventional) in three grassland-dominated regions of Germany on management diversity as well as on overall species number per grassland sampling site (α diversity), per farm (γ diversity) and on the heterogeneity between the sampling sites of each farm (β diversity). The underlying sample comprised 388 vegetation surveys on permanent grassland of 28 farm pairs (HC+LC), whereof 15 were organic and 13 were conventional farm pairs. Phytodiversity indices differed significantly between Concentrate Categories or between Concentrate Categories in interaction with the Farming System. In conventional farming systems grassland phytodiversity at site and farm level (α and γ diversity, respectively) were significantly higher on LC farms than on HC farms and conventional HC farms had less high nature value plant species in their grasslands. On organic farms these parameters were comparable to the conventional LC farms for both Concentrate Categories. In the northern study region phytodiversity indices were overall smaller than in the southern and central study regions. Across regions, management diversity as expressed in the number of grass products on farm level and plant species heterogeneity between sampling sites (β diversity) were higher on LC than on HC farms irrespective of farming systems which was underlined by a significantly positive relationship. On LC farms 4.8 ± 0.9 and on HC farms 4.1 ± 1.3 grass products were produced. Our results indicate that a feeding strategy with low concentrate input is one way to improve grassland phytodiversity, especially in conventional farming systems under central European conditions.

Effect of Level of Concentrate Feeding and Addition of Monensin on Blood Parameters of Awassi Lambs

This study was conducted to investigate the effect of level of concentrate feeding and addition of monensin on blood parameters. Sixteen Awassi lambs were used at 4-6 months of age and mean initial weight of 21.27 kg. Concentrate diet was offered at two levels (2.5 and 3% of body weight, BW) with or without the addition of monensin at a rate of 30 mg/kg DM. Ground wheat straw was offered adlibitum. Results showed that increasing level of concentrate significantly increased (P<0.01) blood concentration of total protein (BTP) from 6.94 to 8.84 g.100 ml-1, urea nitrogen (BUN), and triglyceride (TG) from 15.54 to 18.23 and 22.66 to 25.12 mg.100 ml-1 respectively. The addition of monensin significantly increased (P<0.05) TP concentration from 7.61 to 8.17 g.100 ml-1, whereas, BUN concentration was decreased (P<0.01) from 18.15 to 15.62 mg.100 ml-1. All blood parameters were also affected (P<0.05) by the interaction between the level of concentrate and the addition of monensin. In the study of diurnal changes, blood parameters showed an expected response to the time of withdrawing blood samples from lambs.

Foraging behaviour of gestating sows on pasture and damages to vegetation cover are influenced by restriction of concentrate feed

One of the main challenges of outdoor pig production systems is their potential environmental impact due to direct deposition of pigs’ excreta on the land that can lead to nitrate leaching. However, plants can recycle nutrients, and a sufficient vegetation cover can mitigate adverse environmental impacts of outdoor pigs. The aim of this study was to investigate the impact of concentrate feed restriction on gestating sows foraging behaviour and ensuing damages caused to vegetation cover in a pasture-based system. Ten groups of three sows were randomly assigned to two concentrate feed levels, supplying either 90 % (P90) or 40 % (P40) of metabolizable energy requirements, from week 5 of gestation until farrowing. All groups of sows were housed at a density of 8 sows/ha in a rotational pasture system including a permanent area and three 25 × 50-m legume-grass pasture plots, which could be accessed in rotation for periods of 2–3 weeks. Posture and location of sows were assessed at weeks 8–9, 12–13 and 15 of gestation using data loggers. During the same weeks, video recordings were made when the sows were at pasture, in order to determine their time spent foraging. Vegetation cover of pasture plots was determined at the beginning and end of the grazing periods using a method based on Unmanned Aerial Vehicle-acquired image processing. In the second half of gestation, P40 sows spent 60 % more time active on pasture than P90 sows during the daytime (P < 0.01). The feeding level did not influence the number of daily visits to pasture plots, but P40 sows spent more time on pasture and travelled longer distances per visit than P90 sows. While at pasture, P90 sows spent more time rooting (P < 0.001) and less time grazing (P = 0.002) than P40 sows. In pasture plots with P90 sows, an increasing proportion of bare soil was observed over time, whereas in P40 plots, a greater proportion of high vegetation was replaced by medium vegetation. These results indicate that a higher concentrate restriction promoted grazing behaviour in pregnant sows, leading to greater disappearance of high vegetation but not to greater vegetation cover destruction. In contrast, the lower concentrate restriction increased the proportion of rooting activity, leading to greater damage to vegetation cover. In conclusion, this study has shown that concentrate feeding level of gestating sows on pasture can be reduced without adverse effects on pasture vegetation cover.

Effects of grass and maize silage feed value, offering soybean meal with maize silage, and concentrate feed level in late pregnancy, on ewe and lamb performance

In many countries, daily herbage accumulation on pasture declines towards zero during the winter period; thus, many pregnant ewes are housed and offered conserved forages supplemented with concentrate prior to parturition. The effects of forage type and feed value (FV), offering soybean meal with maize silage during mid and late pregnancy, and concentrate feed level in late pregnancy on the performance of ewes and their progeny (to slaughter) were evaluated. Ewes (n = 151) were assigned to one of nine treatments from mid-pregnancy until lambing. Medium FV and high FV grass silages (metabolisable energy concentrations of 10.7 and 12.0 MJ/kg DM) were offered ad libitum supplemented with either 15 or 25 kg concentrate/ewe during late pregnancy. Low and high DM maize silages (starch concentrations of 80 and 315 g/kg DM) were offered ad libitum either alone or with soybean meal (200 g/d) and supplemented with 15 kg concentrate during late pregnancy. A final treatment consisted of high FV grass silage supplemented with 5 kg soybean/ewe over the final 4 weeks of pregnancy. Ewes and lambs were put to pasture in a rotational-grazing system within 3 days of lambing. There were no interactions (P > 0.05) between grass silage FV and concentrate feed level for ewe or lamb traits. Increasing grass silage FV increased food intake (P < 0.001) during late pregnancy, ewe BW and body condition score (BCS) at lambing (P < 0.001), lamb BW at birth (P < 0.001) and weaning (P < 0.05), and reduced age at slaughter (P = 0.06). Increasing concentrate feed level increased metabolisable energy (P < 0.05) intake during late pregnancy but had no effect (P > 0.05) on ewe or lamb performance. Increasing maize DM at harvest and offering soybean meal with maize silage increased food intake (P < 0.001) and ewe BW and BCS at lambing (P < 0.05 or P < 0.01). Offering soybean meal with maize silage increased lamb BW at birth (P < 0.01) and reduced age at slaughter (P < 0.05). Reducing supplementation of high FV grass silage to 5 kg of soybean meal had no effect (P > 0.05) on animal performance. Replacing grass silage with maize silage did not affect (P > 0.05) BW gain of lambs. It is concluded that increasing the FV of the grass silage offered during pregnancy had the greatest positive impact on ewe and lamb performance.

Effect of dairy cow genotype and concentrate feed level on cow performance and enteric methane emissions during grazing

The current study (40 cows in a 2 × 2 factorial arrangement) compared methane (CH4) emissions from two dairy cow genotypes (Holstein-Friesian [HF], and Swedish Red × [Jersey × Holstein-Friesian] [Crossbred]) offered two levels of concentrate supplementation (3.0 or 6.0 kg/cow per day) while grazing. Enteric CH4 emissions were measured using the SF6 technique on three occasions over a 16 week period, while intakes were estimated using performance data. Increasing concentrate level increased milk and energy corrected milk (ECM) yields, had no effect on CH4 emissions (g day-1) and CH4 emissions per kg dry matter (DM) intake, while reducing CH4/ECM yield. Crossbreds produced milk with higher milk fat and protein contents than HF cows, but ECM yield did not differ between genotypes. Daily CH4 production (g day-1), and CH4 production per kg ECM yield was unaffected by genotype. Methane yield (g kg-1 DM intake) was higher with the Crossbred cows, although DM intake was estimated in this study, and this result should be interpreted with some caution. Thus HF and Crossbred cows had similar CH4 emissions.

Nutrient Adequacy Evaluation of Aceh Cattle Fed with Concentrate for Forage Substitution and Performance Improvement

This study aims to evaluate nutrient adequacy based on the nutrient requirement and intake of Aceh cattle fed by concentrate as a substitution for forage to improve their performance and productivity. The study was conducted from May to July 2018 at Livestock Breeding and Forage Center for Excellence (BPTU-HPT) of Indrapuri, Aceh. Twenty heads of selected male and healthy Aceh cattle aged 1.5-2.5 yo with a weight of ±160 kg were divided into four treatment groups based on different forage and commercial concentrate feed levels, i.e. T1 as a control (fed with 25 kg of forage without any additional concentrate feed), T2 (fed with 20 kg of forage plus 1 kg of concentrate feed), T3 (fed with 15 kg of forage plus 2 kg of concentrate feed), and T4 (fed with 10 kg of forage plus 3 kg of concentrate feed). The data observed were ADG, feed consumption, and nutrient intake, requirement, and balance. Data were analyzed using one-way ANOVA and continued by DMRT. The difference in the amount of forage consumption was very significant (P <0.05), directly proportional to the amount of forage provided. Dry matter intake significantly increased with provision of concentrate (P <0.05). Increases in DM, CP, and TDN intakes were 0.75, 0.16, 0.40 kg/d, respectively. A negative balance was found in almost all nutrients and treatment groups, and there was only one positive balance, i.e. protein in T4 group. T3 group had met the DM requirement, but did not meet protein and TDN requirements, and also had the highest ADG (P <0.05) compared to the other groups. This study concludes that the use of concentrate as a substitute for forage improves nutrient intake of male Aceh cattle. Feeding of 2 kg of concentrate and 15 kg of forage can meet nutrient requirements of dry matter and provide the highest ADG.

The Effect of Grazing System and Level of Concentrate Protein Feeding on Milk Production and N Use Efficiency of Dairy Cows on Peat Meadows

The aim of the study was to assess the effect of two contrasting grazing systems, strip-grazing and kurzrasen, at a high stocking rate on herbage intake and milk production and quality on a peat meadow. Additionally, we assessed the effect of the level of crude protein (CP) fed in concentrate on milk production and N use efficiency. Even at the relatively high stocking rates, cows still achieved substantial fresh grass intake (on average &gt;6 kg dry matter cow−1 day−1) from both systems. Despite the lower level of gross grass production under kurzrasen management, the difference in milk production between kurzrasen and strip-grazing was small and non-significant. Feeding concentrate with a lower CP level, had no negative impact on milk yield, provided that the CP content of the total ration remained above ~150 g kg−1 DM and milk urea content was above ~18 mg 100 g−1 milk. Reducing the CP content in the concentrate significantly increased the N use efficiency, and both were strongly related to the milk urea content. Therefore, optimising the use of milk urea as a management tool on dairy farms, also during the grazing season, could reduce N losses to the environment, while maintaining productivity.

Effect of dietary concentrate to forage ratio on growth performance, rumen fermentation and bacterial diversity of Tibetan sheep under barn feeding on the Qinghai-Tibetan plateau.

This study aimed to research the effects of different dietary concentrate to forage (C:F) ratio on growth performance, rumen fermentation and bacteria diversity of barn feeding Tibetan sheep. The experiment contains fiver treatments (HS1, HS2 HS3, HS4 and HS5; n = 8, respectively) based on dietary C:F ratios 0:100, 15:85, 30:70, 45:55, and 60:40, respectively. The ruminal bacterial community structure was investigated through high-throughput sequencing of 16S rRNA genes in V4 hypervariable region. The results showed that increasing dietary concentrate feed level from 0% to 60% exerted a positive effect on DMI, BW gain, gain rate and feed conversation ratio (FCR) in Tibetan sheep. The increases dietary concentrate feed level elevatedNH3-N, propionate and valerate concentrations, whereas, reduced molar ratio of acetate to propionate (A/P ratio) (P < 0.05). For rumen bacterial diversity, increases in dietary concentrate content contributed to lower alpha diversity indexes including Shannon wiener, Chao1 and observed species, meanwhile, significantly increased the abundances of the phylum Bacteroidetes and the genus Prevotella_1 (P < 0.05). In conclusion, increases dietary concentrate content improved the growth performance and Tibetan sheep fed diets of 45% concentrate obtained a better performance; the inclusion of concentrate in feed changed rumen fermentation from acetate fermentation to propionate fermentation, and improved the energy utilization efficiency of Tibetan sheep; the increased in concentrate content significantly reduced rumen bacteria diversity and changed the abundance of some core bacteria.

Effect of concentrate level on enteric methane emissions, production performance, and rumen fermentation of Jersey cows grazing kikuyu-dominant pasture during summer

The effect of concentrate feeding level on enteric CH4 emissions from cows grazing medium quality summer pasture is yet to be investigated. Sixty multiparous Jersey cows (9 rumen-cannulated) were used in a randomized complete block design study (with the cannulated cows in a 3 × 3 Latin square design) to investigate the effect of concentrate feeding level (0, 4, and 8 kg/cow per day; as-fed basis) on enteric CH4 emissions, production performance, and rumen fermentation of dairy cows grazing summer pasture (17 cows plus 3 cannulated cows per treatment). Enteric CH4 emissions were measured from 11 cows per treatment group during one 7-d measurement period using the sulfur hexafluoride tracer gas technique. Pasture dry matter intake (DMI) was determined parallel with the CH4 measurement period using TiO2 as an external marker, and milk yield, milk composition, cow condition, and pasture pre- and postgrazing measurements were also recorded. Daily total DMI (11.2 to 15.6 kg/cow), milk yield (9.1 to 18.2 kg/cow), energy-corrected milk (ECM; 11.2 to 21.6 kg/cow), and milk lactose content (44.1 to 46.7 g/kg) increased linearly, whereas pasture DMI (11.2 to 8.4 kg/cow) decreased linearly with increasing concentrate feeding level. Daily CH4 production (323 to 378 g/d) increased linearly due to the increase in total DMI, whereas CH4 yield (29.1 to 25.1 g/kg of DMI) and CH4 intensity (35.5 to 21.1 g/kg of milk yield; and 28.8 to 17.6 g/kg of ECM) decreased linearly with increasing concentrate feeding level. Diurnal ruminal pH (6.45 to 6.32) and in sacco DM and neutral detergent fiber disappearance decreased linearly. Acetic and propionic acid were unaffected by treatment, whereas butyric acid (5.21 to 6.14 mM) increased linearly and quadratically with increasing concentrate feeding level. It was concluded that a high concentrate feeding level not only increases animal efficiency but is moreover a viable CH4 mitigation option for dairy cows grazing kikuyu-dominant pasture in late summer when pasture is inherently fibrous.

Effect of concentrate feeding level on methane emissions, production performance and rumen fermentation of Jersey cows grazing ryegrass pasture during spring

Dietary supplementation has been well documented as an effective enteric methane (CH4) mitigation strategy. However, limited studies have demonstrated the effect of concentrate level on enteric CH4 emissions from grazing dairy cows, and to our knowledge none of these studies included a pasture-only diet or reported on rumen fermentation measures. Sixty multiparous (4.0 ± 1.51 SD) Jersey cows, of which six were rumen-cannulated, were used in a randomised complete block design, and the cannulated cows were used in a separate replicated 3 × 3 Latin square design, to investigate the effect of concentrate supplementation (0, 4, and 8 kg/cow per day; as fed) on enteric CH4 emissions, milk production, dry matter intake (DMI), and rumen fermentation of dairy cows grazing perennial ryegrass pasture during spring, following a 14-d adaptation period. The sulphur hexafluoride tracer gas technique was used to measure enteric CH4 emissions from 10 cows of each treatment group over a single 9-d measurement period. Parallel with the CH4 measurement period, pasture DMI was determined using TiO2 and indigestible neutral detergent fibre as external and internal markers, respectively, while milk yield, milk composition, cow condition, and pasture pre- and post-grazing measurements were also recorded. Total DMI (13.4 to 18.0 kg/d), milk yield (12.9 to 19.2 kg/d), energy corrected milk (14.6 to 20.7 kg/d), milk lactose content (46.2 to 48.1 g/kg) and gross energy intake (239 to 316 MJ/d) increased, while milk fat content (50.0 to 44.2 g/kg) decreased with increasing concentrate feeding level. Volatile fatty acid concentrations and ruminal pH were mostly unaffected by treatment, while dry matter disappearance decreased and NH3-N concentration increased with increasing concentrate feeding level. Methane production (258 to 302 g/d) and CH4 yield (20.6 to 16.9 g/kg of DMI) were similar for all cows, while pasture DMI (13.4 to 10.8 kg/d) and CH4 intensity (20.4 to 15.9 g of CH4/kg of milk yield) decreased linearly with increasing concentrate feeding level. Results indicate that concentrate supplementation on high quality pasture-only diets have the potential to effectively reduce CH4 emissions per unit of milk yield from grazing cows during spring.

Effect of Concentrate Feed Level on Weight Change, Intestinal Microbiota, and Blood Profiles of Jeju Cross-Bred Horses

Effect of Concentrate Feed Level on Weight Change, Intestinal Microbiota, and Blood Profiles of Jeju Cross-Bred Horses

1411 The effect of by-product inclusion and concentrate feeding level on milk production and composition, pasture dry matter intake, body weight and body condition score of mid-late lactation spring calving grazing dairy cows

1411 The effect of by-product inclusion and concentrate feeding level on milk production and composition, pasture dry matter intake, body weight and body condition score of mid-late lactation spring calving grazing dairy cows

Effects of Concentrate Feeding Level after Sexual Maturity on the Growth and Breeding Performances, Blood Composition, and Ultrasonic Carcass Traits in Hanwoo Cows

Effects of Concentrate Feeding Level after Sexual Maturity on the Growth and Breeding Performances, Blood Composition, and Ultrasonic Carcass Traits in Hanwoo Cows

Effects of dietary active dried yeast (Saccharomyces cerevisiae) supply at two levels of concentrate on energy and nitrogen utilisation and methane emissions of lactating dairy cows

Twenty early lactation dairy cows were used to evaluate the effects of the dietary addition of an active dried yeast product at two levels of concentrate on productive performance, nutrient digestibility, methane (CH4) emissions and energy and nitrogen utilisation. This study was a replicated 4 × 4 Latin square design with a two (concentrate level) × two (yeast supplement) factorial treatment arrangement, with four periods (6 week/period) and a 3-week interval between each period. Cows were offered grass silage-based diets consisting of two levels of concentrate (300 and 600 g/kg), with or without supplement of 0.5 g/day of an active dry yeast (Saccharomyces cerevisiae strain) with a specification of 2 × 1010 cfu/g. Feed dry matter intake, milk yield, milk composition, bodyweight and body condition score were similar between yeast treatments at both concentrate levels. Nutrient digestibility was not affected by yeast supplementation. Energy intake and faecal, urinary, CH4 and milk energy outputs were also not affected by yeast supplementation. Yeast supplementation had no effects on energy partitioning but tended to increase heat production and decreased energy retention. Yeast supplementation at two levels of concentrate had no effect on total CH4 emissions, but tended to increase CH4 per unit of feed intake and CH4 energy output per unit of gross energy intake. There were no effects of yeast supplementation on CH4 per unit of milk yield. Yeast supplementation had no effect on any variable of nitrogen intake, output or utilisation. Overall, the dietary addition of an active dried yeast product at two concentrate feeding levels had no effects on feed intake, milk production, milk composition, nutrient digestibility, or nitrogen utilisation efficiency and only tended to increase heat production, CH4 per unit of feed intake and CH4 energy output per unit of gross energy intake in lactating dairy cows.

Effects of diet on leather quality and longissimus muscle composition of three Ethiopian indigenous goat types

A 3 × 2 factorial experiment was carried out to evaluate the effect of breed or genotype and levels of concentrate on muscle composition and skin and leather quality characteristics. The three indigenous goat genotypes used were Bati, Hararghe highland (HH), and short-eared Somali (SS), (12/genotype) with an average initial weight of 15.2 ± 0.245 kg. The goats were all males ~1 year of age. After grouping based on their initial weight, they were randomly assigned to two levels of concentrate feeding (six goats per genotype per treatment) and fed for 90 days. The two concentrate feeding levels were C1 and C2, where goats were fed at 1% and 1.5% of their bodyweights, respectively. At the end of the study, all goats were slaughtered and samples were taken from the longissimus muscle for chemical composition analysis. The skins were weighed, preserved and processed into leather for physico-chemical analysis. The longissimus muscle of SS goats had higher (P &lt; 0.05) fat content (7.01%) than Bati (6.05%) and HH (6.02%) goats. Feeding concentrate at 1.5% bodyweight increased carcass weights (P &lt; 0.01), and increased the protein and fat contents of the longissimus muscle by ~5.4% and 3.5%, respectively. Similarly, goats under C2 feeding group had heavier skin than those under C1. However, Bati and HH goats produced 250 g more heavier leather than SS goats. Leathers made from skins of HH goats were thicker (1.56 mm) than those from Bati (1.32 mm) and SS goats (1.23 mm). Leathers from SS goats tended to have lower (P = 0.07) tear strength and higher (P = 0.05) fat content than those from Bati and HH goats. Goats fed C2 produced leathers with higher (P &lt; 0.05) tear strength (51.6 N/mm) and fat content (6.2%) than those fed C1. In conclusion, the study revealed that the meat obtained from the three goat types had low to medium fat content that can meet the needs of diversified consumers. Moreover, they produced quality leather comparable to the quality standard set for good quality leather despite leathers from SS goats tending to have lower tear strength and higher fat content.

The effect of two contrasting concentrate allocation strategies on the performance of grazing dairy cows

AbstractThe objective of this study was to examine the performance of grazing Holstein–Friesian dairy cows when equal quantities of concentrates were offered using either a flat‐rate or a feed‐to‐yield allocation strategy. The study involved fifty‐six cows (twenty primiparous and thirty‐six multiparous) and continued for 122 d, with concentrate feed levels adjusted on five occasions during the study (every four weeks approximately). Total concentrate intake over the duration of the study was 463 and 525 kg cow−1 (3·8 and 4·3 kg cow−1 d−1) for multiparous and primiparous animals respectively. Concentrate allocation strategy had no effect on average daily milk yield, milk fat or protein content, milk‐fat‐plus‐protein yield or end‐of‐study live weight and body condition score (P &gt; 0·05). In conclusion, concentrate allocation strategy had minimal impact on the overall performance of these mid/late lactation cows when concentrate feed levels were modest and grass availability was high.

Effects of concentrate supplementation on enteric methane emissions and milk production of grazing dairy cows

Although concentrate supplements in ruminant diets have been recognised as an effective enteric methane mitigation strategy, very few studies have examined the effects of concentrate supplementation on enteric methane emissions under grazing conditions. Twenty four multiparous Holstein Friesian cows were used in a crossover design study to investigate the effects of two concentrate feeding levels across two periods on enteric methane emissions and milk production of grazing dairy cows. Each period had a duration of four weeks (three weeks for diet adaptation and one week for measurements) and no interval in between them. Dietary treatments consisted of two concentrate feeding levels per cow (1 vs. 5kg; as-fed basis) offered daily in equal meals during milking. Enteric methane emissions from cows grazing perennial ryegrass pasture were measured during the final week of each period using the sulphur hexafluoride tracer technique. Milk yield and liveweight were determined daily during each methane measurement period, whereas milk composition and body condition score (BCS) were determined weekly. Daily herbage intake by individual cows during methane measurement weeks was estimated using an energy requirement model and animal records and diet composition. In period 1, cows receiving 5kg concentrate supplement were estimated to reduce herbage intake by 1.8kg DM/d compared to cows receiving 1kg of concentrate, whereas in period 2 cows receiving the 5kg concentrate supplementation were estimated to reduce herbage intake by 4.4kg DM/d, compared to cows receiving 1kg of concentrate. In both periods, milk yield increased with increasing concentrate level, with an average milk response to concentrate supplementation of 0.68kg milk DM/kg concentrate DM over the two periods. Concentrate feeding level had no effect on milk fat, protein or total solids contents. In period 2, lactose content increased in cows offered 5kg/d concentrate. Increasing concentrate feeding level increased liveweight and BCS in period 1, but not in period 2. Feeding 5kg of concentrate supplement increased enteric methane emission by 34g/d in period 1 (323 vs. 357g/d) and 41g/d in period 2 (349 vs. 390g/d) compared to 1kg of concentrate supplement. However, enteric methane emission per unit of estimated feed intake (dry matter or gross energy) or milk output (gross or energy corrected) was not affected by level of concentrate supplementation. It was concluded that under generous grazing conditions (high allowance of good quality herbage) a moderate increase in concentrate supplementation resulted in a simultaneous increase in milk yield and enteric methane emission, so that enteric methane emission per unit of milk yield was unaffected. Thus, a moderate level of concentrate supplementation of dairy cows grazing pastures of high digestibility would not be an effective enteric methane mitigation strategy.

Effects of shearing, forage type and feed value, concentrate feed level, and protein concentration on the performance of housed finishing lambs.

The effects of high and medium feed value grass silage or maize silage (MS), each offered with a range of concentrate feed levels, and ad libitum concentrate on the performance of finishing lambs, which were either shorn or unshorn, were evaluated. Three silages were used: 1 medium feed value (MFV) and 1 high feed value (HFV) grass silage (DM digestibility [DMD] of 71.3% and 74.5%, respectively) and 1 MS (DM and starch concentrations of 30.9% and 35.3% DM, respectively). The 3 silages were offered ad libitum with daily allowances of 0.4, 0.8, or 1.2 kg concentrate per lamb. Two additional treatments were: 1) MS supplemented with 0.4 kg of a low CP (LP) concentrate and 2) concentrate offered ad libitum with 0.5 kg/d of HFV grass silage. These 11 dietary treatments were offered to 264 crossbred Suffolk lambs (initial BW = 39.0 kg), half of which were unshorn and half of which were shorn, for a 54-d finishing period, resulting in 22 treatments. Shearing increased forage DMI (P < 0.001) but did not alter (P > 0.05) carcass weight, carcass gain, or ADG, and there was no interaction with dietary treatment. Reducing CP concentration of the concentrate offered with MS did not alter (P > 0.05) feed intake or lamb performance. Increasing concentrate feed level increased feed DMI and lamb performance (P < 0.001). The linear response in ADG to increased concentrate supplementation was greater (P = 0.012) for MFV than HFV grass silage, and a corresponding difference in carcass gain approached significance (P = 0.075). The linear response was greater for grass silage than for MS for ADG (P < 0.01) and carcass gain (P = 0.019). The response in lamb performance from increased concentrate supplementation was linear for HFV grass silage and MS but quadratic (P < 0.05) for the MFV grass silage, reflecting the large response for this silage when concentrate supplement was increased from 0.4 to 0.8 kg. Relative to the MFV grass silage supplemented with 0.8 kg concentrate, the potential concentrate-sparing effects of the HFV grass silage and MS were 0.16 and 0.32 kg concentrate per lamb daily, respectively. It is concluded that shearing lambs that are housed during finishing reduces the efficiency of the conversion of ME to carcass gain. Maize silage can replace HFV grass silage in the diet of finishing lambs. The total dietary protein concentration for finishing lambs can be reduced to 9% DM without adversely affecting carcass gain.

Effect of concentrate feed level on methane emissions from grazing dairy cows

Although the effect of nutrition on enteric methane (CH4) emissions from confined dairy cattle has been extensively examined, less information is available on factors influencing CH4 emissions from grazing dairy cattle. In the present experiment, 40 Holstein-Friesian dairy cows (12 primiparous and 28 multiparous) were used to examine the effect of concentrate feed level (2.0, 4.0, 6.0, and 8.0kg/cow per day; fresh basis) on enteric CH4 emissions from cows grazing perennial ryegrass-based swards (10 cows per treatment). Methane emissions were measured on 4 occasions during the grazing period (one 4-d measurement period and three 5-d measurement periods) using the sulfur hexafluoride technique. Milk yield, liveweight, and milk composition for each cow was recorded daily during each CH4 measurement period, whereas daily herbage dry matter intake (DMI) was estimated for each cow from performance data, using the back-calculation approach. Total DMI, milk yield, and energy-corrected milk (ECM) yield increased with increasing concentrate feed level. Within each of the 4 measurement periods, daily CH4 production (g/d) was unaffected by concentrate level, whereas CH4/DMI decreased with increasing concentrate feed level in period 4, and CH4/ECM yield decreased with increasing concentrate feed level in periods 2 and 4. When emissions data were combined across all 4 measurement periods, concentrate feed level (2.0, 4.0, 6.0, and 8.0kg/d; fresh basis) had no effect on daily CH4 emissions (287, 273, 272, and 277g/d, respectively), whereas CH4/DMI (20.0, 19.3, 17.7, and 18.1g/kg, respectively) and CH4-E/gross energy intake (0.059, 0.057, 0.053, and 0.054, respectively) decreased with increasing concentrate feed levels. A range of prediction equations for CH4 emissions were developed using liveweight, DMI, ECM yield, and energy intake, with the strongest relationship found between ECM yield and CH4/ECM yield (coefficient of determination=0.50). These results demonstrate that offering concentrates to grazing dairy cows increased milk production per cow and decreased CH4 emissions per unit of milk produced.