Live Weight Gain Of Sheep Research Articles

Ecological thresholds of toxic plants for sheep production and ecosystem multifunctionality and their trade-off in an alpine meadow

Toxic plants are a natural component of alpine meadow which co-evolved with Tibetan sheep for thousands of years. One challenge for indigenous herders is to know the ecological thresholds of toxic plants and maintain their vital functions in ways that are compatible with economic income and ecological conservation. To achieve this, field trials with Tibetan sheep grazing in alpine meadow were conducted to examine the ecological thresholds of toxic plants for sheep production and ecosystem functions and their trade-offs. Our results demonstrated that the changing point values of biomass proportion of toxic plants for dry matter intake and liveweight gain of sheep were 17% and 22%, respectively. The changing point value of biomass (richness) proportion of toxic plants for soil carbon accumulation index was 31% (59%), for soil nutrient cycling index was 38% (42%), and for ecosystem multifunctionality index was 28% (50%). The trade-off between liveweight gain of sheep and ecosystem multifunctionality first decreased and then increased along the gradient of biomass proportion of toxic plants (the value of changing point was 37%), and had a significant negative correlation with richness of toxic plants. In addition, structural equation modeling indicated that toxic plants can affect the trade-off between liveweight gain of sheep and ecosystem multifunctionality though increasing acid detergent fiber of plant and decreasing plant species richness, belowground biomass and soil total phosphorus. Consequently, opinions towards toxic plants should shift from the conventional view that they are serious threat to grassland ecosystem health to an inclusive understanding that they are beneficial to livestock and ecosystem functions under certain ecological thresholds.

Effect of Grape Marc Added Diet on Live Weight Gain, Blood Parameters, Nitrogen Excretion, and Behaviour of Sheep.

Simple SummaryThis experiment explored how feeding grape wine production waste product grape marc impacts on sheep production. Forty merino sheep were divided into two groups; one group received a sheep industry standard diet (control), and one group received a treatment diet which had 20% of the control diet replaced by grape marc. The results showed that the grape marc diet led to a higher intake and faecal nitrogen/urinary nitrogen ratio, but no difference in sheep live weight gain, behaviour, and parasitic egg count compared with control diet-fed sheep. Overall, the results showed that feeding grape wine production waste product grape marc as a cheap feed, to replace 20% of the control ration, can maintain sheep productivity, health, and environmental sustainability.A 39-day field experiment was conducted to assess the effect of grape marc (GM) feeding on sheep productivity, health, and environmental sustainability. Forty merino sheep were divided into two dietary groups, each having five replications (n = 4 sheep/replication). Experimental diet consisted of: (i) control: 55% lucerne hay + 40% wheat grain + 5% faba bean; (ii) GM treatment: control diet with 20% replaced by GM on a dry matter (DM) basis. The GM treatment contained 2–10% higher phytochemical contents than the control. The DMI from the GM treatment was 15% higher than the control (p < 0.001). No difference was found in sheep live weight gain, behaviour, and quality between groups (p > 0.05). No difference was found in total faecal production, faecal organic matter, and nitrogen contents (p > 0.05) and parasitic egg count. The GM treatment led to higher nitrogen intake (23.1 vs. 27.2 g/d) and faecal nitrogen excretion (6.3 vs. 8.7 g/d) compared to the control. Urinary creatinine, allantoin, and purine derivatives were lower in the GM treatment than control (p < 0.05). However, both groups had similar purine derivatives/DMI (i.e., indicator of rumen microbial protein synthesis efficiency; p > 0.05). Overall, the results showed that GM can replace 20% of the control ration to maintain sheep productivity, health, and environmental sustainability.

Pika burrow and zokor mound density and their relationship with grazing management and sheep production in alpine meadow

AbstractPlateau pikas (Ochotona curzoniae) and plateau zokors (Myospalax baileyi) occur naturally in the alpine meadow of the Qinghai–Tibet Plateau (QTP). Their feeding and burrowing activities affect plant composition and soil properties (e.g., soil carbon accumulation and soil nitrogen cycling), but research to study the complex interactions between small mammals, livestock, and habitat is currently lacking. We conducted a sheep grazing trial to determine the effect of grazing management on pika burrow and zokor mound density, and the relationships between sheep production and pika burrow and zokor mound density. The grazing management approaches were warm‐season rotational grazing at 24 and 48 sheep months (SM)/ha, cold‐season rotational grazing at 24 and 48 SM/ha, seasonal continuous grazing at 24 SM/ha, and whole‐year continuous grazing at 48 SM/ha. The results of this study suggested that warm‐season rotational grazing at low stocking rate did not significantly change both pika and zokor densities. Cold‐season rotational grazing at both high and low stocking rates and seasonal continuous grazing at low stocking rate led to an increase in zokor mound density, but not pika burrow density. Whole‐year continuous grazing at high stocking rate increased both pika and zokor densities. The influence of pika and zokor activities on sheep production was complex and differed between grazing management. Sheep liveweight gain peaked at moderate pika burrow and zokor mound density at low stocking rate under both warm‐ and cold‐season rotational grazing. The threshold values of pika density were about 110 and 70 burrows per hectare in warm and cold seasons, respectively. The threshold value of zokor density was about 400 mounds per hectare in the cold season. In contrast, under high stocking rate regardless of management approach, sheep liveweight gain declined significantly as both pika burrow and zokor mound density increased. This paper provides a theoretical understanding and experimental evidence for sustainable grazing management and restoration of degraded grassland by local herders and policymakers.

Grazing management options for restoration of alpine grasslands on the Qinghai‐Tibet Plateau

AbstractIn an attempt to alleviate the problem of grassland degradation on the Qinghai‐Tibet Plateau in China, state and local authorities in 2003, initiated the “Retire Livestock and Restore Pastures” ecological engineering program, requiring the use of enclosure fencing to enable grazing exclusion and rotational grazing. A five‐year controlled grazing experiment was conducted to determine the effects of this program on (1) sheep live weight gain; and (2a) standing herbage biomass; and (2b) species diversity. Effects of temporal within‐year variation in precipitation and temperature on livestock productivity, standing herbage biomass, and species diversity were also investigated. At the end of 5 yr, grazing exclusion showed no significant difference in standing herbage biomass or in species diversity, compared with either continuous grazing or rotational grazing. Rotational grazing at the high stocking rate significantly promoted sheep live weight gain per hectare, but not per sheep; neither standing herbage biomass, nor species diversity, whether under continuous (i.e., traditional) or rotational grazing, showed a significant difference. Under rotational grazing, higher standing herbage biomass and species diversity were required to maintain or increase sheep liveweight, compared with continuous grazing. Temporal distribution of precipitation and temperature had more influence on alpine grassland parameters, than did grazing. Results of this study suggest that herders’ local traditional knowledge and expertise might be useful in modifying Government guidelines to fine tune grazing management with the dynamics of the alpine meadow ecosystem, and that it is important to consider equilibrium and non‐equilibrium theory in formulating a policy which benefits both herders and grassland. Traditional continuous grazing at a carefully chosen light stocking rate appears to be the most appropriate way to manage livestock and grassland in this region.

Biomass yield and feeding value of rye, triticale, and wheat straw produced under a dual-purpose management system.

Dual-purpose management of winter cereals for grazing and grain production provides highly nutritive forage for ruminants in the spring and may positively affect straw feeding value. A 2-yr study investigated the effect of spring defoliation of triticale, wheat, and rye at the tillering and stem elongation stages on total biomass, grain yields, and straw quality. Furthermore, straws of spring-defoliated and undefoliated (control) cereal crops were evaluated for nutritional value and voluntary intake as a means of assessing the efficiency of dual-purpose management systems from the winter feeding context as well. The feeding study consisted of 9 total mixed rations (TMR), each containing 35% triticale, rye, or wheat straw obtained under 3 spring-defoliation regimens. The TMR were individually fed to fifty-four 1-yr-old Anatolian Merino ewes for 28 d. Defoliation of the crops at tillering did not affect the total biomass production or grain yields. However, biomass and grain yields were reduced ( < 0.01) by 55 and 52%, respectively, in crops defoliated at stem elongation. Straw of spring-defoliated cereals had less NDF and ADF concentrations ( < 0.01) but greater CP ( < 0.01), nonfiber carbohydrates ( < 0.01), and ME concentrations ( < 0.01) compared with straw from undefoliated crops. The increase in the nutritive value of straw led to greater nutrient digestion ( < 0.01) and intake of DM and OM of ewes ( < 0.01). However, sheep live weight gain did not differ among treatments ( > 0.77). This study indicated that straw feeding value and digestibility can be increased through spring defoliation.

The relative strengths of phosphate fertiliser application and white clover cultivar introduction for hill pasture improvement

Abstract Combinations of four phosphorus (P) fertiliser rates (0, 8.5, 22.5 or 26.5 kg/ha/year of citrate-soluble P) and three pasture types with different white clover germplasm, 'resident' cv. Huia and cv. Tahora were compared in self-contained, replicated farmlets grazed by sheep over 4 years. Fertiliser increased white clover herbage accumulation (HA) 3- to 4-fold compared with the control treatment, and increased total sward HA by 50%. Introduction of Tahora white clover significantly increased white clover and total sward HA and nitrogen fixation compared with the resident and Huia-sown swards. Sheep liveweight gain was significantly greater in all systems fertilised with P (438 versus 243 kg/ha for the unfertilised control) and in systems sown with Tahora (425 versus 372 kg/ha for resident and Huia). Keywords: phosphorus fertiliser, white clover, cultivars, herbage accumulation, animal production

Early emergence of axons and formation of accessory nerve (XI) in avian embryos

A research work was undertaken to evaluate the feeding effect of tree forages on performance of growing sheep. Twenty growing sheep (in 4 groups) were fed three different tree forage diets. Tree forages Melia azardirachta, Leucaena leucocephala and Artocarpus heterophyllus were supplied in three treatments except one consisted no tree forages which was considered as control. There were significant (p&lt;0.05) differences among the animal groups in terms of total DM and ME intake, although there were no significant differences in the digestibility of DM, OM, CP and ADF. Feeding of tree forages had significant (p&lt;0.05) effect on live weight gain of sheep. Animals fed with tree forage based diets significantly increased weight gain (60.70 and 50.70 g/d for L. leucocephala and A. heterophyllus, respectively) compared to that (45.66 g/d) of control group fed with silage. Feed conversion efficiency (kg feed/kg gain) also showed that animals fed with tree forage of L. leucocephala and M. azardirachta based diets were having significantly (p&lt;0.05) higher efficiency (11.33 and 11.47, respectively) compared to those of A. heterophyllus and control diet (13.77 and 13.33, respectively). The results of nitrogen balance of M. azardirachta and L. leucocephala tree forage had significantly (p&lt;0.05) positive effect on the nitrogen retention in the body of the animals. Intake of all the tree forages was not similar which indicated that all of them were not accepted to the lamb in same level. So, diets with tree forages of L. leucocephala resulted better in terms of weight gain, digestibility and nitrogen balance compared to A. heterophyllu, M. azardirachta and silage (control).Asian J. Med. Biol. Res. December 2015, 1(3): 654-659

Effect of feeding tree forages on productive performances on growing sheep

A research work was undertaken to evaluate the feeding effect of tree forages on performance of growing sheep. Twenty growing sheep (in 4 groups) were fed three different tree forage diets. Tree forages Melia azardirachta, Leucaena leucocephala and Artocarpus heterophyllus were supplied in three treatments except one consisted no tree forages which was considered as control. There were significant (p&lt;0.05) differences among the animal groups in terms of total DM and ME intake, although there were no significant differences in the digestibility of DM, OM, CP and ADF. Feeding of tree forages had significant (p&lt;0.05) effect on live weight gain of sheep. Animals fed with tree forage based diets significantly increased weight gain (60.70 and 50.70 g/d for L. leucocephala and A. heterophyllus, respectively) compared to that (45.66 g/d) of control group fed with silage. Feed conversion efficiency (kg feed/kg gain) also showed that animals fed with tree forage of L. leucocephala and M. azardirachta based diets were having significantly (p&lt;0.05) higher efficiency (11.33 and 11.47, respectively) compared to those of A. heterophyllus and control diet (13.77 and 13.33, respectively). The results of nitrogen balance of M. azardirachta and L. leucocephala tree forage had significantly (p&lt;0.05) positive effect on the nitrogen retention in the body of the animals. Intake of all the tree forages was not similar which indicated that all of them were not accepted to the lamb in same level. So, diets with tree forages of L. leucocephala resulted better in terms of weight gain, digestibility and nitrogen balance compared to A. heterophyllu, M. azardirachta and silage (control).Asian J. Med. Biol. Res. December 2015, 1(3): 648-653

Evaluation of perennial lupin/cocksfoot pasture relative to lucerne pasture under summer dry conditions

The productivity of a perennial lupin/cocksfoot mix was compared to that of lucerne in summer dry conditions at Lincoln University, Canterbury, New Zealand. The pastures were planted in December 2013 and rotationally grazed by ewe lambs in autumn 2014 (Year 1), and by ewe hoggets in spring-summer and ewe lambs in autumn of 2014/2015 (Year 2) and 2015/2016 (Year 3). For lupin/cocksfoot relative to lucerne in Years 1 to 3, sheep liveweight gains were 54% of 107 kg/ha, 68% of 1134 kg/ha and 50% of 1347 kg/ha; herbage dry matter yields were 122% of 3520 kg/ha, 64% of 10 230 kg/ha and 59% of 9680 kg/ha; and in Years 2 and 3, the water use efficiency of sheep liveweight gain was 76% of 2.0 kg/ha/mm and 49% of 2.7 kg/ha/mm, respectively. The lupin content in the pre-grazing herbage in Years 1 to 3 averaged 42, 22 and 12%, whereas the lucerne content averaged 78, 95 and 98%, respectively. This showed that perennial lupin was not persistent at this lowland site. Keywords: Lupinus polyphyllus, Dactylis glomerata, Medicago sativa, dryland, sheep liveweight gain, water use

Reduced grazing pressure delivers production and environmental benefits for the typical steppe of north China.

Degradation by overgrazing is common in many areas of the world and optimising grassland functions depends upon finding suitable grazing tactics. This four-year study on the northern China steppe investigated combinations of rest, moderate or heavy grazing pressure early in the summer growing season, then moderate or heavy grazing in the mid and late season. Results showed that moderate grazing pressure (~550 sheep equivalent (SE) grazing days ha−1 year−1) gave the optimal balance between maintaining a productive and diverse grassland, a profitable livestock system, and greenhouse gas mitigation. Further analyses identified that more conservative stocking (~400 SE grazing days ha−1 year−1) maintained a desirable Leymus chinensis composition and achieved a higher live weight gain of sheep. Early summer rest best maintained a desirable grassland composition, but had few other benefits and reduced incomes. These findings demonstrate that reducing grazing pressure to half the current district stocking rates can deliver improved ecosystem services (lower greenhouse gases and improved grassland composition) while sustaining herder incomes.

Management of soil phosphorus fertility determines the phosphorus budget of a temperate grazing system and is the key to improving phosphorus efficiency

The phosphorus (P) efficiency of fertilised grazing systems on P deficient soils is often very low. P budgets (P input vs P output) were developed to examine P use in a long-term experiment in which grazing systems were managed with contrasting soil test P concentrations: (i) no P-fertiliser (P0; Olsen P=2–5mg/kg), (ii) near-optimum soil P fertility (P1; Olsen P=10–15mg/kg), (iii) supra-optimal P fertility (P2; Olsen P=20–25mg/kg), or (iv) with variable P fertility. Pastures were grazed with either 9 or 18 sheep/ha. P was exported as liveweight gain in sheep removed from the fields. Fertilised fields accumulated 89–93% of their P input over the whole P-budgeting period (1994–2006). However, this included P that was contributing to a “build up” in soil fertility (1994–2000). The efficiency of P fertiliser use was better demonstrated by P budgets during a soil P fertility “maintenance” phase (2001–2006) in which P inputs and soil test P concentrations of the grazing system treatments were relatively stable. When the amounts of P associated with the small changes in soil fertility were accounted for, the accumulation of P was 43–52kg P/ha (83–87% of P inputs) in P1 fields and 87kg P/ha (88% of P inputs) in P2 fields over the six-year period. Differences due to stocking rate were relatively small. Audits of the total P in sheep camp soil and field soil demonstrated that sheep camps were not a major sink for the P that was accumulating in the grazed fields. P was mainly accumulated in soil in the non-camp area of fields when they were fertilised and this was the major reason for low P-balance efficiency. It was concluded that the annual rate of P accumulation in fertilised soil (due mainly to P-sorption reactions) was higher when soil is being maintained at higher extractable-P concentrations. Consequently, strategies that can achieve equivalent pasture production with lower concentrations of extractable-P in the soil should reduce the amount of P fertiliser necessary for high production.

Dry matter and sheep production of four dryland tall fescue-clover pastures 4-6 years after establishment

Effects of tall fescue cultivar ('Advance' and 'Flecha') and clover species (white and subterranean (sub) clovers) combinations on pasture dry matter (DM) and sheep production were assessed in years four (2011/12), five (2012/13) and six (2013/14) after establishment in dryland, Canterbury. 'Advance' pastures yielded less total herbage than 'Flecha' pastures (13.9 cf. 16.5 t DM/ha) but more fescue (8.6 cf. 5.9 t DM/ha) and 2.1 t DM/ha clover in year four, 13.5 t DM/ha total herbage with more fescue (8.0 cf. 4.1 t DM/ha) and 1.9 t DM/ha clover in year five, and 11.7 t DM/ha total herbage, 5.4 t DM/ha fescue and 0.8 t DM/ha clover in year six. Sub clover pastures yielded more total, fescue and clover herbage (16.9, 8.8 and 3.2 t DM/ha) than white clover pastures (13.5, 5.7 and 1.0 t DM/ha) in year four, more fescue in year five (7.2 cf. 4.9 t DM/ha), and more clover in year six (1.2 cf. 0.3 t DM/ha). Sheep liveweight gain was greater for sub than white clover pastures in year four (939 cf. 431 kg/ha) and five (697 cf. 481 kg/ha) and 689 kg/ha in year six. Therefore, sub clover and 'Advance' were generally more productive than white clover and 'Flecha', but both fescues showed similar persistence after 6 years. Keywords: cultivar, Festuca arundinacea, grass-clover mixtures, liveweight gain, Trifolium subterraneum, Trifolium repens

Effect of concentrate supplementation on herbage intake and live weight gain of sheep grazing a semi-arid grassland steppe of North-Eastern Asia in response to different grazing management systems and intensities

An increasing human population and growing demand for food of animal origin intensified livestock production and lead to overgrazing and desertification in semi-arid grasslands. Strategies for sustainable livestock production that protect steppe vegetation and satisfy farmers׳ economic interests are strongly needed. This study analysed the effects of a moderate concentrate supplementation on organic matter digestibility (dOM), organic matter intake (OMI), metabolisable energy intake (MEI), and live weight (LW) gain of sheep grazing at different intensities to evaluate its potential contribution to profitable livestock production at conservative stocking densities (SD). In 2010, a grazing experiment was conducted in the Xilin River Basin, the Inner Mongolian steppe, China (E116°42′ N43°38′) using 337 female Mongolian fat-tailed sheep (30.2±4.3kg LW). The effect of concentrate supplementation was tested in two different grazing management systems and six classes of herbage allowances (HA). While experimental plots had only been used for grazing in previous years in the continuous system, grazing and hay-making had been alternated annually on plots of the alternating system. The SD ranged from light to heavily grazed with 2.1–10.3 sheep/ha and were adjusted every month to maintain similar HA across the grazing season. Four sheep per plot received 250g/d of a corn–wheat-based concentrate feed (SUP), while four non-supplemented (NSUP) sheep were used as control. Faecal samples were collected on five days each in July, August, and September. The dOM was estimated from faecal crude protein concentration and faeces excretion quantified using the marker titanium dioxide. The animals were weighed monthly to determine daily LW gain. The dOM was higher in SUP than NSUP sheep (0.557 vs. 0.533, RSD: 0.016). As a consequence, daily OMI and LW gain of SUP sheep (74g/kg0.75 LW; 121g) were higher than of NSUP sheep (68g/kg0.75 LW, RSD: 6.4; 86g, RSD: 24.6) despite a decrease in herbage OMI of 0.41g per 1g concentrate feed. Grazing system had no influence on dOM, OMI, or LW gain of sheep. The effects of supplementation were independent of HA class, and OMI, herbage OMI, MEI, and LW gain were higher in the beginning than in the end of the experiment. Moderate concentrate supplementation to grazing sheep strongly increases LW gain of individual animals and might offer a valuable contribution to increase individual productivity, maintaining the output per area at lower SD. A reduced herbage OMI alleviates grazing pressure and can thus maintain long-term grassland productivity.

Feed Intake and Performance of Sheep Grazing Semiarid Grassland in Response to Different Grazing Systems

Effects of grazing management systems (GS) on biomass production and nutritional quality of rangeland vegetation in semiarid regions are extensively studied; however, limited information is available regarding their effects on diet digestibility and feed intake of grazing livestock. We therefore analyzed digestibility of ingested organic matter (dOM), organic matter intake (OMI), and live weight gain (LWG) of sheep in a grazing experiment established in the Inner Mongolian steppe of China, where two GS were tested for six different grazing intensities (GI) from very light to heavy grazing. For the continuous grazing system, sheep grazed the same plots each year, and for the alternating system, grazing and hay making were alternated annually between two adjacent plots. In July, August, and September 2009 and 2010, feed intake and live weight of sheep were determined. The GS did not affect dOM (P = 0.101), OMI (P = 0.381), and LWG of sheep (P = 0.701). Across both GS LWG decreased from 98 g · d-1 for GI1 to 62 g · d-1 for GI6 (P &spilt; 0.001; R2 = 0.42). There were no interactions between GS and GI for all measured parameters (P ≥ 0.061), indicating that alternating grazing did not compensate for negative effects of heavy grazing even after 4 yr of grassland use. In summary, our study showed that irrespective of GI, alternating grassland use does not improve dOM, OMI, and hence, LWG of sheep. However, it might enhance revenues and ecological sustainability in the long term when compared to the common practice of continuous grazing at very high stocking rates.

Impact of grazing intensity on herbage quality, feed intake and live weight gain of sheep grazing on the steppe of Inner Mongolia

SUMMARYThe grassland steppe of Inner Mongolia is traditionally used for sheep grazing. However, overgrazing reduced vegetation cover in winter, thereby increasing soil erosion and consequently, degradation of the steppe vegetation. Grazing intensity (GI) is still the most important factor in pasture management. Hence, the aim of the current study was to evaluate the effect of GI on grassland and sheep performance. A grazing experiment was conducted from July until September in 2005, 2006 and 2007 in which six different GI ranging from very light (GI 1), light (GI 2), light-moderate (GI 3), moderate (GI 4) and heavy (GI 5) to very heavy (GI 6) were tested. Each GI treatment comprised two adjacent plots that were alternately used for grazing or hay-making each year. Variables measured included herbage mass (HM) and chemical composition, digestibility of ingested organic matter (dOM), organic matter intake (OMI) and live weight gain (LWG) of sheep. The HM decreased significantly with increasing GI from 1·01 t (GI 1) to 0·45 t dry matter (DM)/ha (GI 6). There were only minor effects of GI on chemical composition and digestibility of standing herbage. Moreover, dOM, OMI and hence, digestible OMI did not differ between GI. Across all study years, LWG of sheep was not influenced by GI so that LWG per hectare increased with increasing GI, reaching a maximum of 730 g/d at GI 6 compared with 181 g/d at GI 1. However, a strong decrease in LWG per sheep with increasing stocking rate was found in 2005 when annual rainfall was less than half of the long-term average, resulting in a similar LWG per hectare across the range of tested stocking rates. The results therefore show that intensive grazing does not reduce growth of individual animals in most years, but increases LWG per unit of land area and thus, income of farmers. The alternating use of pastures for grazing or hay-making might have mitigated the negative effects of heavy grazing on herbage and animal performance. Nevertheless, high GI may negatively affect grassland productivity in the long term and the lack of HM on offer on heavy grazed pastures in dry years will require supplement feeding at the end of the vegetation period or the untimely sale of animals.

Feeding value of sweet sorghum bagasse and leaf residues after juice extraction for bio-ethanol production fed to sheep as complete rations in diverse physical forms

The fodder value of sweet sorghum bagasse with leaf residues (SSBLR) remaining after juice extraction for bio-ethanol production as major diet ingredient was assessed in male growing sheep measuring intake, digestibility and growth rates. The SSBLR contributed about 450g/kg in total mixed rations and was offered as mash (8mm), pellets (16mm) and feed block (SSBLR chopped). Chaffed SSBLR supplemented with the remaining concentrate components of the total mixed ration-offered for 2h before the chaffed SSBLR-served as a control. Six sheep were randomly allocated to each treatment, balancing the group weight. Intake of all SSBLR based rations was generally very high exceeding 42g/kg of sheep live weight in the control and feed block ration and intake was further increased to 52 and 56g/kg in the mash and pellets rations, respectively. Observed live weight gain in sheep fed mash and pellets were 133g/d and 130g/d, respectively, compared to 90g/d and 81g/d observed in the feed block and control group, respectively. Organic matter digestibility was 0.59 and 0.58 in the mash and pellet group compared to 0.62 and 0.61 in the feed block and control group, respectively. All comparisons in mash and pellet versus feed block and control group were different (P<0.05). SSBLR can be utilized as major ration component thereby mitigating fodder shortages likely to arise from using sweet sorghum stalks for juice extraction for bio-ethanol production. Use of SSBLR as ration component for will also add to the economic viability of sweet sorghum ethanol value chains. In decentralized systems where juice is extracted from sweet sorghum stalks in the villages and options of processing SSBLR are limited, SSBLR can be used in chopped form with similar efficiency than as component of processed feed block. In centralized system, generating large quantities of SSBLR, processing feed into mash and pellets would be advantageous for supporting higher livestock productivity and lower feed transport costs.

Growth of sheep as affected by grazing system and grazing intensity in the steppe of Inner Mongolia, China

The Inner Mongolian grassland steppe is the most important grazing land in China in terms of cow milk, mutton, and cashmere production. However, intensive livestock grazing has severely degraded the steppe grassland. A sophisticated grazing management is therefore essential for an economically viable use of the grassland without amplifying its desertification. The objective of this study was to evaluate the effects of different grazing management systems and grazing intensities (GI) on liveweight gain (LWG) of sheep grazing the Inner Mongolian steppe in order to derive recommendations for a sustainable grassland use which considers both, farmers' interests of a profitable livestock production as well as environmental goals. A 5-year grazing experiment was conducted in June–September of 2005–2009 in which six different GI's (≥12, 6–12, 4.5–6, 3–4.5, 1.5–3, and ≤1.5kg herbage dry mass kg−1 liveweight) and two different grazing systems were installed. The two systems included an alternating grazing system where grazing and hay-making alternated annually between two plots, and a continuous grazing system where the same plots were used either for hay-making or for grazing each year. Grazing system had no or only minor effects on sheep's LWG. However, LWG per sheep linearly decreased with increasing stocking rate, resulting in diminishing responses in LWG per ha. LWG per sheep and per ha were lowest in a dry year and decreased with advancing vegetation period. In view of our earlier published data on the effect of GI on the steppe vegetation, we conclude that grazing at GI's which allows for an end-of-season biomass that is sufficient to prevent grassland degradation does not lead to large deprivations in liveweight yield. Complementary management strategies such as supplement feeding of grazing animals may compensate for this deprivations as well as for inter- and intra-annual variations in herbage growth and quality. They can thus further contribute to a sustainable use of Inner Mongolian steppe.

Evaluation of feeding value of Eupatorium adenophorum in combination with mulberry leaves

The feeding value of sun dried Ea ( Eupatorium adenophorum, Ea ) leaves in combination with mulberry ( Morus alba, Ma) was studied by in vitro gas production (IVGP) technique and in vivo feeding experiment with sheep. The IVGP involved both kinetic assay and ruminal fermentation attributes (gas production, CH4, volatile fatty acids (VFA), purines and digestibility parameters). IVGP data from the combined substrates having Ea at 5.0, 7.5, 10.0, 15.0, 20.0, 30.0, 40.0, 50.0 and 100.0% levels with Ma ruminally incubated for 72 h were studied by using single pool Logistic model. The in vitro result was validated in vivo involving eighteen sheep (18 mo, average BW 22.5 ± 1.1 kg) which were randomly distributed in three equal groups. Group 1 served as control and fed with a complete diet having concentrate mixture and wheat straw at 50:50 ratio. In groups 2 and 3, the concentrate was replaced at 50% level with Ma and Ma + Ea (60:40 ratio), respectively. A digestion trial was conducted after 3 months of experimental feeding for assessing feed and nutrient intake and digestibility. The potential gas production (B) revealed an increasing trend up to 40% (from 41.5 to 48.5 ml) accompanied by a decreasing lag (L, from 2.15 to 0.69 h), increase in rate maxima (μ m, from 2.18 to 3.02) and a decrease in halfway time to the maximum gas volume (t 1/2, from 11.73 to 8.72 h) and all these values reversed at higher inclusion levels. CH 4 production showed a declining trend with the increase in Ea in the substrate (20% reduction with 100% Ea). VFA production (mM/g DM) decreased from 3.69 to 2.47 with a consequent decrease in acetate: propionate ratio from 4.39 to 3.14 at Ea 40%. True DM digestibility decreased at Ea higher than 40%. Partitioning factor (PF) and efficiency of microbial protein synthesis also showed an increasing trend up to 40% Ea. The feeding experiment in sheep showed non-significant difference in DM and nutrient intake between the groups, but there was a marked depression (P < 0.001) in digestibility of nutrients when concentrate was replaced with Ma, which declined further with the inclusion of Ea. However, the animals showed positive live weight gain (average daily gain 20 g/d) and the difference from other dietary groups was non-significant. On the basis of positive in vitro ruminal fermentation data (lower total gas, CH 4, VFA, improved acetate: propionate ratio, higher digestibility, microbial protein synthesis, PF) for Ma 60+ Ea40 and in vivo data on the forage mixture with Ea having high CP (223 g/kg DM), moderate intake and OM digestibility (0.599) sustaining minimum live weight gain in sheep, the encroaching eupatorium biomass can partly substitute costly protein concentrates and may have potential to be incorporated in the complete diet. However, long term feeding experiment is warranted to rule out its toxic effect.

Impact of grazing intensity on herbage intake, composition, and digestibility and on live weight gain of sheep on the Inner Mongolian steppe

High grazing pressure during the last decades caused severe ecological problems in the steppe of Inner Mongolia, China. The objective of the present study was to determine the effects of grazing intensity of sheep on herbage mass (HM) and intake, chemical composition and digestibility of herbage, and on live weight gain (LWG). A grazing experiment with six different grazing intensities (1.5, 3.0, 4.5, 6.0, 7.5, and 9.0 sheep/ha) was conducted in the growing season of 2005 in the Xilin River Basin. HM decreased from 1.5 t DM/ha at the lowest grazing intensity to 0.6 t DM/ha at the highest grazing intensity. NDF content of the herbage was high (> 700 g/kg DM) and relatively constant, whereas acid detergent lignin (ADL) content increased with grazing intensity and with proceeding grazing season. Digestibility of organic matter ingested (DOM) tended to decrease with grazing intensity as well as intake of organic matter (OMI) and of digestible organic matter (DOMI) per sheep ( P = 0.090 and P = 0.065, respectively), whereas LWG per sheep decreased with increasing grazing intensity ( P = 0.018). DOM and OMI were negatively related to ADL content. However, herbage intake and LWG per ha increased with grazing intensity ( P < 0.001) and reached their maximum at 9 and 7.5 sheep per ha, respectively. This observation confirms the current farmers' practise of high grazing pressure ignoring long term grassland productivity and ecological problems. Therefore, the studies are continued to provide further information on long term effects. This study could show pronounced effects of grazing intensity on animal and grassland productivity and the suitability of the methods applied to measure intake and digestibility of herbage in a large scale grazing experiment with sheep.

Increasing dietary sodium chloride increases wool growth but decreases in vivo organic matter digestibility in sheep across a range of diets

For 8 weeks, 64 Merino wethers, 18 months of age, were individually penned and offered 1 of 16 treatment feeds (n = 4). The 16 feeds were formulated to contain levels of added sodium chloride (0, 7, 14, 21%) and levels of organic matter digestibility (55, 62, 69, 76%), in a 4 × 4 factorial design. The treatment feeds were offered ad libitum for 7 weeks and at maintenance for the final week. Clean wool growth, corrected for digestible organic matter intake, increased by 16, 18 and 27% as added sodium chloride was increased (7, 14, and 21%). The increase in wool growth was similar for diets at all levels of formulated organic matter digestibility. Feed digestibility in sheep decreased when added dietary sodium chloride was 14% or higher. The decrease in organic matter digestibility was ~5 percentage units at the highest level (21%) of dietary sodium chloride. Liveweight gain in sheep was reduced from 143 to 134, 65 and 1 g/day with 7, 14 and 21% added dietary sodium chloride, respectively. Therefore, improvement in wool growth efficiency appears to occur at the expense of liveweight gain, and was probably related to a shift in digestion of feed from the stomach to the small intestine. Higher corrected clean wool growth associated with lower levels of purine derivatives (an indicator of microbial protein synthesis) supported the conclusion that increased dietary salt resulted in an increase in dietary protein being digested in the small intestine. A shift in feed utilisation towards increased wool growth as dietary salt increases may be a management tool of particular interest to specialist wool producers. In areas of saline land where salt-accumulating shrubs are often the most productive vegetation, an increase in wool production efficiency, even if liveweight is only maintained, may improve the profitability of incorporating these shrubs into a feeding strategy.