Effect of long-term application of animal slurries to grass on silage feeding quality for sheep

The effect of slurry type (pig or cow) and use of a bacterial silage inoculant, was assessed on herbage from long-term slurry plots ensiled in pilot-scale (0·7 tonne) silos. Silage was fed to sheep to assess digestibility and metabolisable energy content. The latter was measured by direct calorimetry in a modified cattle respiration chamber. Non-inoculated slurry-treated silages had poorer fermentation quality than inoculant-treated silages (P < 0·001) and silages treated with cow slurry had poorer fermentation quality than those treated with pig slurry (P < 0·001). Digestibility values for different components of the silages showed few differences. Energy digestibility values of pig slurry-treated silages were lower (P < 0·05) than for cow slurry-treated silages. Methane production from all animals in the experiment was comparatively low at 5·97–6·74% of gross energy intake. Metabolisable energy contents of the cow slurry-treated silages were higher than pig slurry-treated silages (P < 0·05) and the ME contents of inoculant treated silages were higher than of non-inoculated silages (P < 0·001). Thus, treatment of slurry-treated silages with bacterial inoculant enhanced fermentation quality and ME contents. The effect of slurry type on fermentation quality and feeding value was ambiguous; cow slurry-treated silages exhibiting poorer fermentation quality but higher ME contents than equivalent pig slurry-treated silages. © 1998 Society of Chemical Industry.     

哈萨克羊不同部位脂肪特性的研究

研究了新疆哈萨克羊不同部位脂肪的组成成分差异。采用气相色谱-质谱法对新疆哈萨克羊的肾周脂、网膜脂以及尾脂的脂肪酸组成及挥发性成分进行了分析。结果表明:在尾脂中共检测出20种脂肪酸,而在肾周脂和网膜脂中均检出17种脂肪酸;其中尾脂的饱和脂肪酸(SFA)含量为49.09%,以棕榈酸(C16∶0)的含量最高;肾周脂中SFA的含量为59.44%;网膜脂中SFA的含量为64.00%;肾周脂和网膜脂中SFA均以硬脂酸(C18∶0)的含量最高。在尾脂中不饱和脂肪酸(UFA)的含量为50.48%,在肾周脂中UFA的含量为38.95%,在网膜脂中UFA的含量为35.15%;不同部位脂肪中UFA均以油酸(C18∶1n-9c)的含量最高。羊脂中的挥发性物质主要由醛类、酯类、醇类和酮类组成。     

The effect of the physical form of the diet and the level of feeding on the digestion of dried grass by sheep

Intact and rumen cannulated sheep were used to study the digestion of an artificially dried grass offered either in a chopped or a ground and pelleted form at energy intakes ranging from 1–3.2 × the energy requirement for meantenance. In each form of the grass the digestibility of all dietary constituents was depressed at high levels of feeding and, excepting ether extract, was lower in the ground and pelleted grass than in the chopped grass. The digestibility of organic matter (DOM) varied with treatment from 70.7–82.7% and for each form of grass was related to the level of feeding (LF) such that DOMC = 83.1–1.01 LF (P < 0.05) and DOMG = 84.6–4.12 LF (P < 0.001). Corresponding relation-ships were observed between the mean retention time of food residues in the alimentary tract (MRT) and the level of feeding (LF) such that MRTC = 111.7–95.1 log LF (P < 0.001) and MRTG = 77.2–60.8 log LF (P < 0.001). Where animals were fed on ground and pelleted grass there were changes in rumen fermentation characterised by a lowered rumen pH and cellulolytic activity and by reduced concentrations of ammonia-N and total short-chain fatty acids in the rumen fluid. The percentage of acetic acid in the fermentation products was decreased and there were associated increases in the percentages of butyric acid and valeric acid. The results indicate that grinding and pelleting the grass was associated with a reduction in the digestibility of organic matter resulting partly from an increased rate of flow of digesta through the alimentary tract and partly from a reduction in cellulolytic activity in the rumen.     

Digestion and absorption of lipids by sheep fed chopped and ground dried grass

Three wether sheep equipped with re-entrant cannulae at the proximal duodenum and terminal ileum were given dried cocksfoot in the chopped or ground form and the samples of duodenal and ileal digesta and faeces obtained for both diets were analysed for individual long-chain fatty acids. The total quantities of fatty acids entering the proximal duodenum (15.2 and 15.4 g/24 h on chopped and ground feed, respectively) were markedly higher than the amounts consumed (8.7 and 7.8 g/24 h, respectively), whilst losses within the small intestine were 13.9 and 14.2 g/24 h, respectively. None of these effects was found to be significantly influenced by the processing of the diet (P > 0.05). The quantity of C₁₈ unsaturated fatty acids in the two feeds comprised 78% of the total fatty acids but the level of these acids was considerably reduced (19%) in duodenal digesta and was not significantly influenced by diet (P > 0.05), whilst the levels of stearic acid (C_18:0) entering the small intestine were markedly increased on both diets.     

Effect of grass or concentrate feeding systems on lamb carcass and meat quality

Thirty-two male Ile de France lambs were divided into four equal groups at age 37 days. Two groups were allowed to graze a natural pasture in France each at a different growth rate (grass high and grass low groups). The other two groups were raised in stalls and fed concentrates to achieve the same growth rates (stall high and stall low groups, respectively) as from the grass groups. The animals were slaughtered when they attained 35 kg and their carcass and meat quality were evaluated. Animals from the two high growth rate groups were slaughtered at an average age of 129 days while those from the low growth rate groups were slaughtered at 163 days. Carcasses from stall-fed lambs were heavier than those from grass-fed lambs as the digestive tract percentage was higher in the grass lambs. Carcasses from stall lambs had better muscular conformation score (P <0.05) and were fattier than those from grass-fed animals. Subcutaneous fat was more yellow and harder in grass-fed lambs (P <0.05). Meat from grass-fed lambs was darker (P <0.05) in colour (lower L*) than meat from stall animals up to 24 h of display. Meat from stall fed animals was more tender and juicier than meat from grass-fed animals (P <0.01), as judged by a trained panel of assessors. Typical lamb flavour was higher in stall-fed lambs (P <0.01). Meat from grass-fed animals had more pronounced liver flavour (P <0.05) and less fatty flavour (P <0.01) than stall-fed lambs. Overall the difference in meat quality between the two different growth rates was minimal.     

Fat partition and distribution in the carcasses of cattle, sheep and pigs: A review

Results from recent Meat and Livestock Commission studies on fat partition and distribution are reviewed, together with those from other published work. Attention is drawn to the commercial importance of these characteristics and to the fact that little is known about their variability, in particular the extent to which fat partition is influenced by environmental factors. Information available from breed trials indicates that there is substantial genetic variation for all three species in the partitioning of fat between depots, although there is less variation in the way in which a given weight of subcutaneous fat or intermuscular fat is distributed through the carcass.     

The effect of supplemental methionine and inorganic sulphate on the ruminal digestion of grass silage in sheep

The effects of an intra-ruminal infusion of a mixture of methionine (7.0 g day^?1) and sodium sulphate (6.7 g day^?1) on the digestion of grass silage were examined in four sheep fitted with cannulas in the rumen and proximal duodenum. There were no significant (P>0.05) effects of the infusion on the ruminal digestion of OM, cellulose or N, or on the concentrations of total or individual VFA in the rumen fluid though the numbers of protozoa in the rumen were reduced (P<0.05). The amounts of total methionine or of bacterial nitrogen reaching the duodenum were not significantly (P>0.05) altered by the infusion and rates of bacterial synthesis were 21 and 23 g N kg^?1 OM (s.e.d. 3.7, P>0.05) apparently digested in the rumen for the control and infusion treatments respectively. The infusion resulted in a significant (P<0.01) increase of 21% in the amount of total long-chain fatty acids at the duodenum. This reflected an increased flow of all fatty acids of chain-length 14:0 and above though more than 80% the response was accounted for by the increased flow of 18:0 and 16:0 acids. It is concluded that the infused supplement stimulated the synthesis of microbial lipid in the rumen.     

Short communication: Effects of feeding level on energy concentration in grass silage-based diets offered to dairy cattle

Twelve grass silages were offered to sheep as a sole diet at maintenance and to lactating dairy cows ad libitum as mixed silage and concentrates diets (n = 13 diets). Fecal and urinary energy outputs were measured for silages and mixed diets. Digestible energy (DE) and metabolizable energy (ME) concentrations for mixed diets with sheep at maintenance were estimated based on the silage dry matter (DM) proportion obtained in the cattle trials, the silage energy utilization values (methane energy-predicted) determined using sheep, and tabulated concentrate values. A comparison of dietary mean data (n = 13) indicated that concentrations of ME (P < 0.01) and DE (P < 0.001) in mixed diets were significantly lower for cows at production feeding level than for sheep at maintenance. The reductions were proportionately 0.015 and 0.020 with each unit increase in feeding level above maintenance, respectively. These ME and DE data were also used to evaluate the feeding level correction factors previously proposed by Van Es (1975) (ME, 0.018) and Yan et al. (2002) (ME, 0.016; DE, 0.025) using the mean square prediction error technique. The ME correction factor proposed by Yan et al. (2002) had a greater prediction accuracy than that proposed by Van Es (1975) for the prediction of ME concentration in mixed diets offered to dairy cattle at production feeding level.     

Diffusivities of volatiles in concentrated solutions

Concentration profiles obtained by slicing a cylindrical gel were used to measure diffusion of volatiles in viscous aqueous dextrose solutions. The column length, slice thickness and diffusion time were optimized to maximize the repeatability of measurements, the results being very sensitive to small changes in variables. Coefficients of variation between 5 and 10% were obtained. In the presence of different concentrations of dextrose, the diffusivity of acetone decreased markedly as dextrose concentration increased. However, when the acetone concentration was varied within the range 0·6 to 13·7%, at a constant 50% (w/w) dextrose concentration, its diffusivity did not change significantly. The sliced gel system gave values of diffusivity in close agreement with those obtained by other techniques.     

白兰地中非酒精挥发物总量的测定

本文采用气相色谱法对白兰地中的酯类、醛类、糠醛、高级醇等进行测定,并采用化学法测定白兰地的挥发酸,从而得出体现白兰地重要质量指标的非酒精挥发物总量.采用Varian CP WAX57CB毛细管柱(50m×0.25mm,0.2μm),内标法定量测定白兰地挥发性成分中的酯类、醛类、糠醛、高级醇.该法简单、迅速,只需30min即可测得白兰地的20种挥发性成分.与国家白兰地标准GB11856-1997中规定的方法相比,更简单、快速.并且在测定挥发酸时较国标法有所改进.     

Evaluation of different energy feeding systems with production data from lactating dairy cows offered grass silage-based diets

A set of data from 838 lactating dairy cows, drawn from 12 long-term feeding studies (at least 8 wk/period), was used to evaluate the energy feeding systems for dairy cows currently adopted in Australia, France, The Netherlands, the United Kingdom, and the United States. The animals were offered mixed diets of concentrates, forage [grass silages (n = 33) and corn silages (n = 5)] ad libitum. Data used in the present evaluation were either measured [dry matter (DM) intake, milk production and live weight], measured/estimated [dietary metabolizable energy (ME) concentration] or estimated [milk energy output and live weight change (LWC)]. The mean-square prediction error (MSPE) was used for the evaluation. Total ME intake, milk yields, and LWC varied from 91 to 338 MJ/d, 7.7 to 48.9, and -1.23 to 1.73 kg/d, respectively. Australian and French systems predicted total energy requirement and milk yield relatively well, while British, Dutch and American systems underpredicted total energy requirement by proportionately 0.06, 0.04, and 0.03, respectively; and overpredicted milk yield by 0.09, 0.06, and 0.04. The Agricultural and Food Research Council (AFRC) each produced a relatively larger error of the bias (predicted - actual data) over the total MSPE for ME requirement and milk yield and a relatively smaller error of random than other systems. However, an addition of proportionately 0.05 to the total predicted ME requirement of AFRC, as suggested in this system and currently used in the UK, indicated the prediction accuracy of ME requirement and milk yield is similar to Australian and French systems. Nevertheless, all the systems had a poor prediction of LWC. For each system, the total prediction error (total MSPE) was mainly derived from the line (slope; 0.49 to 0.64 of total MSPE), while less derived from the random (0.20 to 0.48 of total MSPE), indicating a large variation between the predicted and actual LWC existed among individual cows. The residual plots of the residual differences in LWC against predicted LWC revealed that the prediction error was greater with increasing LWC. It is concluded that Australian and French systems have a better prediction of total energy requirement and milk yield than other systems, and LWC is an inappropriate indicator of energy balance in lactating dairy cows.     

The effect of feeding system in the expression of genes related with fat metabolism in semitendinous muscle in sheep

The effect of feeding system on the expression of LPL, ACACA, FASN, FABP4, DGAT1, SCD, CPT1B, PRKAA2, LEP, SREBP1, PPARG, PPARA and CEBPB genes in semitendinous muscle was studied. Forty-four single born male lambs of the Rasa Aragonesa breed, allocated to four different dietary treatments, were used: grazing alfalfa, grazing alfalfa with supplement for lambs, indoor lambs with grazing ewes and drylot. Significant differences were found in the expression of genes LPL, ACACA, FASN, FABP4, CPT1B and SCD. Genes related to adipogenesis (LPL, ACACA, FASN, FABP4, and SCD) are up-regulated in the intensive groups. In grazing groups CPT1B gene expression, related to β-oxidation process, is up-regulated. The relative expression of CPT1B was 1.54 fold higher in ALF+S, and 0.43 and 0.37 fold lower in IND- GRE and IND, respectively. The results support the hypothesis that changes in fatty acid profile due to feeding system implicate changes in the mRNA expression level of genes related with fat metabolism. Feeding strategy is an important tool to manipulate intramuscular fatty acid profile in meat through altering gene expression of enzymes related with fat metabolism.     

Verification of fresh grass feeding,pasture grazing and organic farming by FTIR spectroscopy analysis of bovine milk

In the present study, a total of 116 tank milk samples were collected from 30 farms located in The Netherlands and analysed by Fourier-transform infrared (FTIR) spectroscopy. Samples were collected in April, May and June 2011 and in February 2012. The samples differed in the time spent by the cows on pasture, presence/absence of fresh grass in the daily ration and the farming system (organic/biodynamic or conventional). Classification models based on partial least square discriminant analysis (PLS-DA) of FTIR spectra were developed for the prediction of fresh grass feeding, pasture grazing and organic farming. The PLS-DA model discriminated between milk from cows that had fresh grass in the daily ration and milk from cows that had not fresh grass with sensitivity and specificity values of 88% and 83% in external validation and all the samples from cows that had no fresh grass collected in spring were correctly classified. The PLS-DA model developed for the authentication of pasture grazing showed comparable accuracy when the whole sample set is considered but was less accurate on the spring samples (75% of samples from cows indoors in spring correctly classified). Discrimination of organic and conventional milk was also accomplished with acceptable accuracy with % correct classification of 80% and 94% respectively in external validation. The results suggest that milk FTIR spectra contain valuable information on cows' diet that can be used for authentication purposes.     

Effect of including barley or molassed sugar beet feed in grass silage diets on their digestion by cattle and sheep

The objective of the experiment was to compare the digestion of barley, a starch-based feedingstuff, with molassed sugar beet feed (SBF), a high-fibre, sugar-containing feedingstuff, when fed to cattle and sheep receiving silage. There were between-species differences in rumen measurements. Sheep had higher mean daily rumen ammonia-N concentrations; the molar proportions (mmol mol^?1 total rumen volatile fatty acids) of propionic acid were higher and those of n-butyric acid lower in sheep than in cattle. The feeding of barley was associated with increased rumen populations of protozoa and increased rumen ammonia-N concentrations compared with the feeding of SBF. There were no significant differences between the diets fed in whole tract or rumen digestion of organic matter or nitrogen. However, feeding SBF tended to increase the quantities of non-ammonia-N and microbial N entering the small intestine daily: feeding barley did not improve N flow to the small intestine.     

Effect of dosing regime on intake estimation using the n‐alkane technique in sheep fed pelleted grass meal

An experiment was carried out to evaluate the n‐alkane technique for estimating the voluntary intake of pelleted grass meal by sheep. Two groups of 12 Scottish Blackface sheep were dosed once daily or twice daily with paper pellets containing 130 mg of C₃₂ alkane. Mean daily intakes over a 5 day period were estimated from n‐alkane concentrations in faeces and compared with actual intakes measured by weighing of food. Two faecal sampling frequencies were compared (once or twice daily) at each dosing frequency. Diurnal patterns of intake were determined by weighing food residues every 3 h for 4 days. Diurnal patterns of faecal n‐alkane concentration were determined from rectal grab samples collected every 3 h for 2 days. There was no effect of dosing frequency on actual intake. Estimated intake was higher for twice‐daily than once‐daily dosed animals when twice‐daily faecal sampling was employed (P < 0.05), although differences between mean actual and estimated intakes were not significant. The accuracy of estimation of individual intakes was better for sheep dosed once daily, at both faecal sampling frequencies, than for sheep dosed twice daily. This may have been due to diurnal variation in food intake and digesta outflow from the rumen, demonstrating the importance of matching n‐alkane dosing and sampling regimes to the digesta kinetics of the diet fed. © 2000 Society of Chemical Industry     

The effect of addition of mixtures of amino acids on the intake of grass silage by sheep and cattle

A mixture of 15 amino acids was either added to the basal silage diet (sheep and cattle) or infused intraruminally (cattle) to determine the role of amino acids in the control of silage intake. Neither dietary addition nor intraruminal infusion of the amino acid mixture in sheep or cattle had a significant effect on intake compared to the control (P > 0·05). However, in cattle, dietary addition of the amino acid mixture increased intake compared with intraruminal infusion of the amino acid mixture (P < 0·01). It was concluded that the amino acid content of the basal silage is not involved in the control of silage intake by sheep or cattle. © 1998 SCI