Cereal-based Concentrates Research Articles

Milk production potential of whole crop faba bean silage compared with grass silage and rapeseed meal

The objective of the present study was to compare the effect of whole crop faba bean silage with grass silage as forages for lactating dairy cows. The experiment also allowed comparison of the milk production response of faba bean crude protein (CP) to that derived from a rapeseed meal supplement. Three experimental diets were used: (1) Grass silage supplemented with a cereal-based concentrate (CON), (2) 75% of grass silage replaced on dry matter (DM) basis with whole crop faba bean silage supplemented with a cereal-based concentrate (FB) and (3) Grass silage supplemented with a cereal and rapeseed meal-based concentrate (RSM) so that it was isonitrogenous with FB. The diets were fed as total mixed rations and the target proportion of concentrate in total diet DM was 400 g/kg. The experimental design was a nine times replicated 3 × 3 Latin square and 27 dairy cows were recruited into the experiment. Diet DM intake was significantly greater (P < 0.05) with FB and RSM compared with CON, which was reflected in lower (P < 0.05) milk, energy corrected milk and milk protein outputs of cows on CON than those on FB and RSM. There were no significant differences in milk and protein yields between FB and RSM but energy corrected milk and milk fat yields were greater on RSM (P < 0.05). Milk urea content was lowest in CON and highest on FB while RSM was intermediate (P < 0.05). Whole crop faba bean silage provides a viable option for feed production of dairy farms under Northern European climatic conditions with positive influence on e.g., biodiversity and flexibility in harvesting schedules. In spite of the moderate energy value of faba bean silage, it has a good feed intake potential, and when replacing grass silage in the diet, can be assumed to maintain or even increase milk yield. The higher supply of CP from FB compared to that of grass silage is however not as valuable as that originating from rapeseed meal, and decreasing nitrogen use efficiency seems inevitable irrespective of the source of additional CP content in the diet of dairy cows.

Canonical discriminant analysis of the fatty acid profile of muscle to authenticate beef from grass-fed and other beef production systems: Model development and validation

The potential of diet-induced differences in the fatty acid profile of muscle to discriminate beef from different feeding systems and its potential use as an authentication tool was investigated. Three canonical discriminant models were built and validated using the fatty acid profile of beef from animals fed solely on pasture or cereal-based concentrates for 11 months or on various pasture/grass silage/concentrate combinations, including concentrates enriched with plant oils. Results indicated that models could successfully discriminate between grass-, partially grass- and concentrate-fed beef (accuracy = 99%) and between grass-fed beef and beef from animals supplemented with plant oils (accuracy = 96%). The approach also showed potential for distinguishing between beef from exclusively pasture-fed cattle and beef from cattle fed on pasture preceded by a period on ensiled grass (accuracy = 89%). Models were also applied to beef samples from 9 different countries. Of 97 international samples, including samples stated to be grass-fed, only 5% were incorrectly classified as Irish-grass-fed beef. These results suggested that the models captured traits in the fatty acid profile that are characteristic of Irish grass-fed beef and that this feature could be used for distinguishing Irish grass-fed beef from beef from other regions.

Effect of Citrus By-product on Physicochemical Parameters, Sensory Analysis and Volatile Composition of Different Kinds of Cheese from Raw Goat Milk.

The increased use of concentrates to reduce pasture as a feed source in productive systems like Payoya breed goat farms has made it necessary to decrease feeding costs. The inclusion of agro-industry by-products such as dry orange pulp pellets in goat diets has been suggested as a sustainable alternative to cereal-based concentrates. The aim of this work was to assess the influence of diets including dry orange pulp pellets on the quality of cheeses traditionally made from Payoya breed goat milk. We analysed the physicochemical characteristics, sensory properties and volatile compound profiles of 18 artisanal cheeses made from raw Payoya milk. In this study, goats were fed with different concentrations of dry orange pulp; and cheeses were curdled with animal and vegetable coagulants. Slight differences were detected between some cheeses. However, the use of citrus by-products in the Payoya goat diets did not substantially affect the cheeses’ physicochemical properties, olfactory attributes, or volatile profiles. Therefore, dried citrus pulp can be used as a substitute for cereal concentrates without affecting the distinct properties of these ripened raw goat milk cheeses.

Dietary pomegranate by-product improves oxidative stability of lamb meat

This study investigated the effect of including whole pomegranate by-product in lamb diet on meat oxidative stability. Seventeen lambs were assigned to two experimental treatments and fed a cereal-based concentrate (CON) or the same concentrate where 200 g/kg DM of cereals were replaced by whole pomegranate by-product (WPB). Meat from WPB-fed lambs had a greater concentration of vitamin E (α- and γ-tocopherols), polyunsaturated fatty acids (PUFA), highly peroxidizable PUFA and a higher peroxidability index (P < .05). Feeding WPB limited the formation of metmyoglobin (P = .05) and reduced lipid oxidation (TBARS values) after 7 days of storage for raw meat (P = .024) or 4 days for cooked meat (P = .006). Feeding WPB increased meat antioxidant capacity (ORAC assay) in the lipophilic fraction (P = .017), but not in the hydrophilic. These results suggest that vitamin E in the pomegranate by-product contributed to the higher antioxidant capacity of meat from the WPB-fed lambs.

Predicting milk responses to cereal-based supplements in grazing dairy cows

The feeding of cereal-based supplements is common in the Australian dairy industry, as it allows cows to increase intakes of total dry matter (DM) and metabolisable energy (ME), while achieving greater stocking rates, greater pasture utilisation and greater milk production per hectare than occurs when cows are fed pasture-only diets. However, for this practice to be profitable, it is important to know how much extra milk, milk protein and milk fat are produced for each kilogram DM consumed. This is difficult to determine in such a complex biological system. We combined information from 24 concentrate-feeding experiments using meta-analysis techniques, so as to develop improved prediction models of the milk, milk protein and milk fat produced when cereal-based concentrates are fed to grazing, lactating dairy cows. Model terms, consistent with biological processes, linear, quadratic and factorial, were selected according to statistical significance. The models were then tested in two ways, namely, their goodness of fit to the data, and their ability to predict novel production data from a further six, unrelated, experiments. A sensitivity analysis was also undertaken to determine how sensitive these predictions are to changes in key inputs. The predictive model for milk yield was shown to very closely reflect milk yield (kg/cow.day) measured under the experimental conditions in unrelated experiments (r = 0.96), with very little bias (Lin’s bias correction factor = 0.98) and high concordance (Lin’s concordance coefficient = 0.95). Predictions generated by multiplying predicted milk protein concentration by predicted milk yield closely matched observed milk protein yield (kg/cow.day) (r = 0.96, Lin’s bias correction factor = 0.98, Lin’s concordance coefficient = 0.95), and predictions found by multiplying predicted milk fat concentration by predicted milk yield closely matched observed milk fat yield (kg/cow.day) (r = 0.94, Lin’s bias correction factor = 0.99, Lin’s concordance coefficient = 0.93). Factors included in the new models for milk, milk protein and milk fat yield reported here have been identified previously as elements that can influence milk production. The value to the dairy industry from being able to predict profitable amounts of concentrates to feed at various stages throughout lactation is considerable. For farmers and their advisers, being able to apply these models to estimate the immediate marginal milk protein and milk fat responses to supplementary feeds should lead to more robust, efficient and profitable milk production systems.

Volatiles in raw and cooked meat from lambs fed olive cake and linseed

This study was conducted to determine the effects of feeding olive cake and linseed to lambs on the volatile organic compounds (VOCs) in raw and cooked meat. Four groups of eight male Appenninica lambs each were fed: conventional cereal-based concentrates (diet C), concentrates containing 20% on a dry matter (DM) basis of rolled linseed (diet L), concentrates containing 35% DM of stoned olive cake (diet OC), or concentrates containing both rolled linseed (10% DM) and stoned olive cake (17% DM; diet OCL). The longissimus dorsi muscle of each lamb was sampled at slaughter and was subjected to VOC profiling through the use of SPME-GC-MS. In the raw meat, the concentration of 3-methylpentanoic acid was higher in treatment C as compared with treatments L, OC and OCL (P<0.01). Moreover the level of nonanoic acid was greater in treatments C and OC than in treatment L (P<0.05). With respect to alcohols, in raw meat the amount of 2-phenoxyethanol in treatment OCL was lower than in treatments C (P<0.01) and OC (P<0.05), while in cooked meat the amount of 1-pentanol was higher in treatment C than in treatment OC (P<0.05). Apart from these compounds, none of the lipid oxidation-derived volatiles was significantly affected by the dietary treatment. Therefore, the results suggest that the replacement of cereal concentrates with linseed and/or olive cake did not cause appreciable changes in the production of volatile organic compounds in lamb meat.

Microbial and chemical composition of liquid-associated bacteria in goats' rumen and fermenters

This study was undertaken to investigate the relationship between chemical composition and microbial profile of rumen liquid-associated bacteria (LAB) in vivo (Murciano-Granadina goats) and in a rumen simulation system (single-flow continuous-culture fermenters). To achieve this aim, analyses of purine bases along with some molecular techniques (quantitative PCR to assess abundance and DGGE to identify biodiversity and bacterial profile) were carried out. A control diet (AHC) based on alfalfa hay (AH) and concentrate (C) in a 1:1 ratio and two experimental diets (AHCBI and AHCBII), in which concentrate was partially replaced with multinutrient blocks, were used. Diets AHCBI and AHCBII included multinutrient blocks differing in the relative amount of two-stage olive cake and the source of protein (sunflower meal vs. fava beans). We aimed to investigate the effect of these blocks on rumen microbiota to evaluate their potential as safe substitutes of cereal-based concentrates. Similar patterns of response to diet were found for chemical composition, microbial abundances and diversity in LAB isolated from goat's rumen and fermenters. Whereas bacterial density (log10 gene copies/g FM: 11.6 and 9.4 for bacteria and methanogens, respectively, in rumen) and diversity indexes (Shannon index: 3.6) were not affected by diet, DGGE analyses showed that bacterial community profile was affected. The cluster analysis suggested differences in bacterial profile between LAB pellets isolated from the rumen of goat and fermenters. A relationship between chemical composition and bacterial community composition in LAB pellets seems to exist. Changes in the former were reflected in the bacterial community profile. Further research is needed to clarify the relationship between chemical and microbial composition of ruminal bacterial pellets with diets of different quality.

The use of stoned olive cake and rolled linseed in the diet of intensively reared lambs: effect on the intramuscular fatty-acid composition

The aim of the present study was to evaluate the effect of the inclusion of stoned olive cake and rolled linseed in a concentrate-based diet for lambs on the fatty-acid composition of polar and non-polar intramuscular lipids of the longissimus dorsi muscle. To achieve this objective, 32 Appenninica lambs were randomly distributed into four groups of eight lambs each and were fed conventional cereal-based concentrates (diet C); concentrates containing 20% on a dry matter (DM) basis of rolled linseed (diet L); concentrates containing 35% DM of stoned olive cake (diet OC); and concentrates containing both rolled linseed (10% DM) and stoned olive cake (17% DM; diet OCL). The concentrates were administered together with grass hay at a 20:80 forage:concentrate ratio. Growing performances and carcass traits were evaluated. The fatty-acid composition was analysed in the total intramuscular lipids, as well as in the polar and neutral lipids. The average feed intake and the growth performance of lambs were not affected by the dietary treatments, as a consequence of similar nutritional characteristics of the diets. The inclusion of rolled linseed in the L and OCL diets increased the content of C18:3 n-3 in intramuscular total lipids, which was threefold higher in meat from the L lambs and more than twofold higher in meat from the OCL lambs compared with the C and OC treatments. The n-6:n-3 ratio significantly decreased in the meat from lambs in the L and OCL groups, reaching values below 3. The L treatment resulted in the highest level of trans-18:1 fatty acids in the muscle. Regardless of the dietary treatment, the t10-18:1 was the major isomer, representing 55%, 45%, 49% and 45% of total trans-18:1 for C, L, OC and OCL treatments, respectively. Neutral lipids from the OC-fed lambs contained the highest amount of c9-18:1 (more than 36% of total fatty acids); however, the content of c9-18:1 did not differ between the OC and C lambs, suggesting an intensive biohydrogenation of dietary c9-18:1 in the case of OC treatment. The highest content of c9,t11-18:2 was detected in the intramuscular fat from the L-fed lambs, followed by the OCL treatment. A similar trend was observed in the neutral lipid fraction and, to a lower extent, in the polar lipids.

Effects of dam breed and dietary source of n-3 polyunsaturated fatty acids on the growth and carcass characteristics of lambs sourced from hill sheep flocks

The objectives of this study were to investigate the effect of dietary lipid source on the growth and carcass characteristics of lambs sourced from a range of crossbred hill ewes. Over a 2-year period, 466 lambs representing the progeny of Scottish Blackface (BF × BF), Swaledale (SW) × BF, North Country Cheviot (CH) × BF, Lleyn (LL) × BF and Texel (T) × BF ewes were sourced from six commercial hill flocks and finished on one of four diets: grass pellets (GP), cereal-based concentrate (CC), CC enriched with oilseed rape (CR) and CC enriched with fish oil (CF). Dry matter intake (DMI) was highest (P < 0.001) in lambs offered GP; however, carcass weight gain (CWG) and feed conversion efficiency were higher (P < 0.001) in lambs fed concentrate-based diets. For lambs offered concentrate-based diets, DMI and live weight gain were lower (P < 0.001) for CF than CC or CR. Lambs with T × BF dams achieved a higher (P < 0.05) daily CWG and CWG/kg DMI than BF × BF, SW × BF or LL × BF dams. When lambs were slaughtered at fat score 3, CH × BF, LL × BF and T × BF dams increased carcass weight by 0.8 to 1.4 kg (P < 0.001) and conformation score (CS) by 0.2 to 0.4 units (P < 0.001) compared with BF × BF or SW × BF dams. However, breed effects on carcass conformation were reduced by 50% when lambs were slaughtered at a constant carcass weight. Diets CC and CR increased carcass weight by 0.8 to 1.6 kg (P < 0.001) and CS by 0.1 to 0.3 units (P < 0.001) compared with GP and CF. Both, dam breed and dietary effects on carcass conformation were associated with an increase (P < 0.001) in shoulder width of the lambs. Lambs fed CF and slaughtered at a constant carcass weight had more subcutaneous fat over the Longissumusdorsi (P < 0.05), Iliocostalisthoracis (P < 0.001) and Obliquus internusabdominis (P < 0.001) compared with those fed CC. However, these effects were removed when lambs were slaughtered at a constant fat score. At both endpoints, lambs from T × BF dams contained less (P < 0.05) perinephric and retroperitoneal fat than SW × BF or LL × BF dams fed GP or CC, respectively. The results from this study show that using crossbred ewes sired by CH, LL or T sires will increase carcass weight and improve carcass conformation of lambs sourced from hill flocks. Inclusion of oilseed rape in lamb finishing diets had only minor effects on performance compared with a standard CC but feeding fish oil or GP impacted negatively on lamb growth and carcass quality.

Energy balance, milk production and reproduction in grazing crossbred cows in the tropics with and without cereal supplementation

This study was designed to evaluate the role of supplementation with a cereal-based concentrate on energy balance, milk production and reproduction of suckling crossbred cows, grazing star grass in the tropics. Forty-eight Holstein × Zebu cows were used in a 2 × 2 factorial design from calving to 98 days post-partum. Treatment factors were diet (Control vs. Supplemented) and season of calving (dry vs. rainy). The supplement consisted of sorghum (69%), soya bean meal (14%), wheat bran (15%) and minerals (2%), contained 878 g/kg dry matter (DM), 168 g/kg DM crude protein (CP) and 11.8 MJ/kg DM metabolisable energy (ME), and was offered at 0.9% of live weight. There was no interaction between diet and season. Supplementation increased ( P < 0.001) intakes of DM, ME and CP, and increased milk yield by 30% ( P < 0.001). Supplementation eliminated negative energy balance (NEB) on day 21 post-calving (3.3 vs. − 22.9 MJ/day) and on day 84 post-calving (1.1 vs. − 12.1 MJ/day). The proportion of cows that showed oestrus was higher ( P = 0.025) for Supplemented cows (74%), compared with Control cows (39%) and the proportion of cows that ovulated tended to be greater ( P = 0.073) for Supplemented (58%) than for Control (30%) cows. Supplemented cows had a greater ( P = 0.003) population of large ovarian follicles (0.6 vs. 0.3), shorter ( P = 0.025) calving to first oestrus interval (62.8 ± 6.9 days vs. 68.2 ± 3.8 days) and tended to have ( P = 0.079) a higher pregnancy rate at 90 days (47% vs. 22%). It is concluded that grazing crossbred cows in the tropics may experience a period of NEB post-partum, which can be reduced using cereal-based concentrates, whilst improving milk production and reproductive performance.

A comparison of the aroma volatiles and fatty acid compositions of grilled beef muscle from Aberdeen Angus and Holstein-Friesian steers fed diets based on silage or concentrates

This paper compares the volatile compound and fatty acid compositions of grilled beef from Aberdeen Angus and Holstein-Friesian steers slaughtered at 14 months, each breed fed from 6 months on either cereal-based concentrates or grass silage. Linoleic acid levels were higher in the muscle of concentrates-fed animals, which in the cooked meat resulted in increased levels of several compounds formed from linoleic acid decomposition. Levels of α-linolenic acid, and hence some volatile compounds derived from this fatty acid, were higher in the meat from the silage-fed steers. 1-Octen-3-ol, hexanal, 2-pentylfuran, trimethylamine, cis- and trans-2-octene and 4,5-dimethyl-2-pentyl-3-oxazoline were over 3 times higher in the steaks from the concentrates-fed steers, while grass-derived 1-phytene was present at much higher levels in the beef from the silage-fed steers. Only slight effects of breed were observed.

Effect of time of feeding carbohydrate supplements and pasture on production of dairy cows

The productivity and rumen status of Friesian cows grazing short rotation Italian ryegrass ( Lolium multiflorum) pastures was examined in relation to the time of grazing and of feeding cereal-based concentrates. In experiment 1, 42 cows grazed as seven separate groups of six cows on ryegrass pasture over a 2-day period, and were fed 2 kg crushed barley grain/cow at morning and evening milking on the first day. On the second day, no concentrates were fed at morning milking and a different group of cows was removed at random from grazing and a rumen sample collected by stomach tube at 0, 1, 2, 3, 4, 5, 7 and 9 h after commencement of grazing at 07:00 h. Sampling concluded before afternoon milking at 17:00 h. Rumen ammonia (NH 3) concentration peaked and pH fell to its lowest value between 7 and 9 h after cows commenced grazing. In experiment 2, 42 cows were stratified into three groups of 14 cows on the basis of milk and component yield, age, liveweight and calving date and randomly allocated within blocks to one of three treatments. Over a 10-day adjustment period and a 21-day experimental period, cows were given their daily pasture allocation of 13.5 kg DM/cow (above 5 cm stubble height) either after morning milking, and fed crushed barley grain at morning and evening milking in the ratio of 3:1 kg/cow (Synch) or 1:3 kg (Asynch) or given their daily allocation of pasture after afternoon milking with barley fed at a ratio of 3:1 kg/cow (PM) in the morning and evening milking. Based on the results of experiment 1, the feeding schedule for the Synch group was predicted to more closely synchronise the availability of N from pasture and readily fermentable carbohydrates (RFC) from concentrates, in the rumen, compared to the Asynch cows. The comparison between Synch and PM groups was to determine the relative importance of ‘synchrony’ compared to feeding pasture (afternoon) high in water soluble carbohydrates (WSC) content. The WSC content of ryegrass pasture sampled after morning milking (when the Asynch and Synch groups received their new pasture allocation) was 70 and 74 g/kg DM, respectively, compared to 124 g/kg DM for samples taken after afternoon milking (when the PM group received a new pasture allocation). Pasture dry matter intake (DMI) and in vivo digestibility of individual cows was determined by use of alkanes as inert markers, whilst group DMI was determined from pre- and post- grazing pasture mass estimated by rising plate meter. Rumen samples were taken by stomach tube at 0, 3, 7 and 11 h after grazing commenced in the morning on the last day of the experiment. On this same day the % of cows grazing was recorded at 10-min intervals. Nitrogen intake (733 g N/cow/day) was 280% above requirements and this resulted in rumen NH 3 concentrations being three times higher than the concentration at which microbial protein synthesis (MPS) would be expected to become limited. Milk (25.1, 24.3 and 26.8 l/cow/day; ( P=0.05)) and protein (809, 794 and 850 g/cow/day; P<0.05) yield for the Asynch, Synch and PM groups, respectively, differed significantly. Pasture DMI was not significantly different ( P>0.05) but DM digestibility was ( P<0.001) at 84% for the mean of the Asynch and Synch cows compared to 88% for the PM cows, respectively. The results of the present study indicate a substantial benefit of feeding cows pasture with a high WSC content. This can be achieved by giving the cows their daily allocation of pasture after afternoon milking in the knowledge that WSC accumulates during the day and that over 70% of the intake of pasture by cows will be consumed in the first 3–4.5 h of grazing a fresh pasture allocation. Under the conditions of this study there was no production benefit from attempting to synchronise the availability of N and RFC in the rumen by timing of WSC supplementation. This presumably indicates that MPS was not limiting the daily milk yield of 25–26 l/cow when these cows consumed high N ryegrass pastures.

Effect of dietary fish oil on biohydrogenation of fatty acids and milk fatty acid content in cows

AbstractMechanisms underlying milk fat conjugated linoleic acid (CLA) responses to supplements of fish oil were investigated using five lactating cows each fitted with a rumen cannula in a simple experiment consisting of two consecutive 14-day experimental periods. During the first period cows were offered 18 kg dry matter (DM) per day of a basal (B) diet formulated from grass silage and a cereal based-concentrate (0·6 : 0·4; forage : concentrate ratio, on a DM basis) followed by the same diet supplemented with 250 g fish oil per day (FO) in the second period. The flow of non-esterified fatty acids leaving the rumen was measured using the omasal sampling technique in combination with a triple indigestible marker method based on Li-Co-EDTA, Yb-acetate and Cr-mordanted straw. Fish oil decreased DM intake and milk yield, but had no effect on milk constituent content. Milk fat trans-11 C18:1, total trans-C18 : 1, cis-9 trans-11 CLA, total CLA, C18 : 2(n-6) and total C18 : 2content were increased in response to fish oil from 1·80, 4·51, 0·39, 0·56, 0·90 and 1·41 to 9·39, 14·39, 1·66, 1·85, 1·25 and 4·00 g/100 g total fatty acids, respectively. Increases in the cis-9, trans-11 isomer accounted for proportionately 0·89 of the CLA response to fish oil. Furthermore, fish oil decreased the flow of C18 : 0(283 and 47 g/day for B and FO, respectively) and increased that of trans-C18 : 1fatty acids entering the omasal canal (38 and 182 g/day). Omasal flows of trans-C18 : 1acids with double bonds in positions from delta-4 to -15 inclusive were enhanced, but the effects were isomer dependent and primarily associated with an increase in trans-11 C18 : 1 leaving the rumen (17·1 and 121·1 g/day for B and FO, respectively). Fish oil had no effect on total (4·36 and 3·50 g/day) or cis-9, trans-11 CLA (2·86 and 2·08 g/day) entering the omasal canal. Flows of cis-9, trans-11 CLA were lower than the secretion of this isomer in milk. Comparison with the transfer of the trans-9, trans-11 isomer synthesized in the rumen suggested that proportionately 0·66 and 0·97 of cis-9, trans-11 CLA was derived from endogenous conversion of trans-11 C18 : 1in the mammary gland for B and FO, respectively. It is concluded that fish oil enhances milk fat cis-9, trans-11 CLA content in response to increased supply of trans-11 C18:1that arises from an inhibition of trans-C18 : 1reduction in the rumen.

Effects of pasture grazing or storage feeding and concentrate input between 5·5 and 11 months of age on the performance and carcass composition of bulls and on subsequent growth and carcass composition at 620 kg live weight

AbstractA 3-year experiment has been carried out to compare systems of bull beef production involving pasture grazing and continuous storage feeding and to examine the effects of sward surface height and concentrate input from 5·5 to 11 months of age on grazing behaviour, growth rate and body composition at the end of the treatment period and on subsequent growth rate and carcass composition at commercial slaughter weight. Animals were either set-stocked at pasture to maintain sward surface heights of 6·5 and 10·0 cm or were given grass silage (725 g digestible organic matter per kg dry matter (DM)) supplemented with 0·8, 1·6, 2·4, 3·2 and 4·0 kg cereal-based concentrates (188 g crude protein per kg DM) per head daily. Half of the animals grazed at each sward height were given 1 -6 kg concentrates per head daily while the remainder received no supplement. A total of 255 continental beef breed × Friesian calves which were initially 198 kg live weight were used. From 11 months of age until slaughter at a mean live weight of 620 kg all animals were given grass silage supplemented with 3 kg cereal-based concentrate DM per head daily.Reducing sward surface height from 10·0 to 6·5 cm increased the proportion of time spent grazing (P &lt; 0·001), reduced the proportion of time involved in other activities and reduced live-weight gain (P &lt; 0·001) from 1·21 to 0·84 kg/day. Offering concentrates at pasture reduced (P &lt; 0·001) the proportion of time spent grazing (the effect being greater with the animals grazing the shorter swards) but did not affect the performance of the animals grazing the taller swards and produced only a modest increase in the live-weight gain (70 g/kg concentrates) of those grazing the shorter swards. At the end of the treatment period, the carcasses of the animals which had been given silage contained proportionally 0·39 more lipid than those of animals which had been at pasture and had the same growth rate. Differences in live weight at 11 months of age due to differences in feeding from 5·5 to 11 months were largely retained until the end of a 7-month period of realimentation while differences in carcass composition at II months were eliminated by slaughter at a constant live weight of 622 kg.

Dietary factors associated with milk somatic cell counts in dairy cows in Brittany, France

A survey (Enquête Ecopathologique Bretagne) was conducted in France for 4 years (1986–1990) in 48 commercial dairy herds (25–80 cows per herd) located in Brittany. Three groups of herd-years were made up to study peripartum dietary factors associated with milk somatic cell counts in the early lactation period (ECC). The first group included 20 herd-years with high ECC (over 400 000 cells ml −1). The second group included herdyears with medium ECC ( n = 20, median ECC 222 000) and the last group herd-years with low ECC ( n = 20, median ECC 95 000). Herd data (components of the diet, milk yield and reproduction parameters, clinical diseases, biochemical and hematological indicators, body and dirtiness scores) were analyzed using discrimination by barycentric analysis. Two separate analysis were conducted according to study period (LG period, last 60 days of gestation; EL period, first 60 days of lactation). The high ECC group had the following characteristics: (1) higher plasma gamma glutamyl transferase levels in the LG period; (2) higher quantities of cereal-based concentrates in the diet in the EL period; (3) shorter durations of feeding with Italian rye grass silage in the EL period. The relevance of the risk factors for high ECC are discussed with reference to dietary linolenic acid/linoleic acid ratio (through the synthesis of leukotrienes as chemotactic agents for the polymorphonuclear leukocytes), dietary energy supplies and liver fluke infestation in the herds. We speculate that nutritional factors could modulate the leukocyte activity in the milk and that supplementations with certain polyunsaturated fatty acids would be able to prevent the development of inflammation in the udder.

A comparison of pasture grazing and storage feeding, and the effects of sward surface height and concentrate supplementation from 5 to 10 months of age on the lifetime performance and carcass composition of bulls

AbstractA 3-year experiment was carried out to compare systems of bull beef production involving continuous housing or pasture grazing from 5 to 10 months of age and to examine the effects of herbage allowance and concentrate supplementation on lifetime performance and carcass quality. Animals were either set-stocked at pasture to maintain nominal sward heights of 7, 9 and 11 cm or were offered grass silage (700 g digestible organic matter per kg dry matter (DM)) supplemented with 1·5 and 3·0 kg barley-based concentrates (183 g crude protein per kg DM) per head daily. Half of the animals grazed at each sward height were given 1·5 kg concentrates per head daily while the remainder received no supplement. A total of 160 continental X Friesian and 48 Friesian calves which were initially 197 kg live weight were used. From 10 months of age until slaughter at about 17 months all animals were given grass silage ad libitum and supplemented with 3·0 (year 1) or 3·75 (years 2 and 3) kg cereal-based concentrates per head daily.Animals which grazed the 9- and 11-cm swards produced carcasses of similar weight to those given silage and 3·0 kg concentrates per day, while those grazing the 6·7-cm swards produced carcasses of similar weight to those given silage supplemented with 1·5 kg concentrates. Reducing sward surface height from 11·0 to 9·3 cm did not affect performance but further reductions to 7·9 (year 1) and 6·7 (years 2 and 3) cm reduced live-weight gain by 0·13 and 0·32 kg/day respectively. Concentrate supplementation did not affect the performance of animals grazing swards which were 7·9 cm or taller but increased live-weight gain by 93 and 193 g/kg concentrates for those grazing the 6·7 cm swards and those receiving silage respectively. Differences in live weight at 10 months of age due to the feeding treatments imposed from 5 to 10 months of age were largely retained until slaughter at 17 months as there was little compensatory growth during the residual period. The treatments did not affect carcass composition when the data were adjusted to a constant carcass weight, or meat quality which was satisfactory for all treatments.

A note on the use of kale as a replacement for cereal-based concentrates for milk production

SUMMARYTwenty-four lactating cows were used in a 6-week randomized block experiment to assess the effect of replacing 2·4 kg of cereal-based concentrate dry matter by either 2·6 or 3·2 kg of kale dry matter for cows with ad libitum access to grass silage. Milk yield, milk composition and live-weight change were not affected by the inclusion of kale. Silage dry-matter intake was significantly lower on the kale treatments than with concentrate, being 8·51, 7·89 and 7·95 kg per day for the concentrate, low-kale and high-kale supplements respectively. Energy digestibilities were 68·1, 74·4 and 76·4% and nitrogen digestibilities 67·1, 74·9 and 78·8% for the three treatments respectively.