Microbial transformations in the rumen ecosystem have a major impact on our ability to meet the challenge of reducing the environmental footprint of ruminant livestock agriculture, as well as enhancing product quality. Current understanding of the rumen microbial ecosystem is limited, and affects our ability to manipulate rumen output. The view of ruminal fermentation as the sum of activities of the dominant rumen microbiota is no longer adequate, with a more holistic approach required. This paper reviews rumen functionality in the context of the microbiota of the rumen ecosystem, addressing ruminal fermentation as the product of an ecosystem while highlighting the consequences of this for ruminant agriculture. Microbial diversity in the rumen ecosystem enhances the resistance of the network of metabolic pathways present, as well as increasing the potential number of new pathways available. The resulting stability of rumen function is further promoted by the existence of rumen microbiota within biofilms. These protected, structured communities offer potential advantages, but very little is currently known about how ruminal microorganisms interact on feed-surfaces and how these communities develop. The temporal and spatial development of biofilms is strongly linked to the availability of dietary nutrients, the dynamics of which must also be given consideration, particularly in fresh-forage-based production systems. Nutrient dynamics, however, impact not only on pathway inputs but also the turnover and output of the whole ecosystem. Knowledge of the optimal balance of metabolic processes and the corresponding microbial taxa required to provide a stable, balanced ecosystem will enable a more holistic understanding of the rumen. Future studies should aim to identify key ecosystem processes and components within the rumen, including microbial taxa, metabolites and plant-based traits amenable to breeding-based modification. As well as gaining valuable insights into the biology of the rumen ecosystem, this will deliver realistic and appropriate novel targets for beneficial manipulation of rumen function.

Analysis of 16S ribosomal RNA (rRNA)-encoding gene sequences from gut microbial ecosystems reveals bewildering genetic diversity. Some metabolic functions, such as glucose utilisation, are fairly widespread throughout the genetic spectrum. Others, however, are not. Despite so many phylotypes being present, single species or perhaps only two or three species often carry out key functions. Among ruminal bacteria, only three species can break down highly structured cellulose, despite the prevalence and importance of cellulose in ruminant diets, and one of those species, Fibrobacter succinogenes, is distantly related to the most abundant ruminal species. Fatty acid biohydrogenation in the rumen, particularly the final step of biohydrogenation of C18 fatty acids, stearate formation, is achieved only by a small sub-group of bacteria related to Butyrivibrio fibrisolvens. Individuals who lack Oxalobacter formigenes fail to metabolise oxalate and suffer kidney stones composed of calcium oxalate. Perhaps the most celebrated example of the difference a single species can make is the ‘mimosine story’ in ruminants. Mimosine is a toxic amino acid found in the leguminous plant, Leucaena leucocephala. Mimosine can cause thyroid problems by being converted to the goitrogen, 3-hydroxy-4(1H)-pyridone, in the rumen. Observations that mimosine-containing plants were toxic to ruminants in some countries but not others led to the discovery of Synergistes jonesii, which metabolises 3-hydroxy-4(1H)-pyridone and protects animals from toxicity. Thus, despite the complexities indicated by molecular microbial ecology and genomics, it should never be forgotten that gut communities contain important metabolic niches inhabited by species with highly specific metabolic capability.

Intensifying concerns about the use of antimicrobials in meat and poultry production has enhanced interest in the application of prebiotics, probiotics and enzymes to enhance growth and prevent disease in food animals. Growth-promoting antibiotics enhance growth of animals by reducing the load of bacteria in the intestine, by reducing colonization by intestinal pathogens or by enhancing the growth and/or metabolism of beneficial bacteria in the intestine. Recently, molecular ecology, utilizing DNA-sequence heterogeneity of the 16S rRNA gene, has revealed a surprising diversity of uncharacterized bacteria inhabiting this ecosystem. We used this approach to determine the effect of growth-promoting antibiotics on the development and composition of the ileal bacterial community. Pairwise comparisons, correspondence analysis and community diversity indices revealed significant differences among the treatments (bacitracin/virginiamycin or monensin) and controls. Antibiotics reduced the diversity of the ileal bacterial community and induced communities rich in Clostridia throughout the life of the broiler chicken. These results indicate that some bacterial species, such as lactobacilli, were suppressed and also suggest that many intestinal Clostridia may be non-pathogenic. Future studies should focus on characterizing the important bacterial species needed to stabilize the intestinal microbiota and identifying those commensals that stimulate and enhance development of intestinal function.

A database built from 95 experiments with 303 treatments was used to quantify the ruminal biohydrogenation (BH) of fatty acids (FA), efficiency of microbial protein synthesis (EMPS), duodenal flow and intestinal absorption of total FA and of FA with 12 to 18 C units, in response to variations in dietary FA content, source or technological treatment of fat supplement. Flows of FA were expressed relative to dry matter intake (DMI) to compile data from bovine and ovine species. BH tended to increase curvilinearly with FA intake, whereas dietary FA did not affect EMPS. A linear relationship between FA intake and duodenal flow of total FA was obtained, with a coefficient of 0.75 ± 0.06 g duodenal FA/kg DMI for each g FA intake/kg DMI. Between experiments, positive balances of total FA (intake – duodenum) were related to low EMPS. Relationships between duodenal flows of FA with 12 to 18 C units and their respective intakes were linear, with a coefficient that increased with the number of C units. Duodenal flow of bacterial FA was linearly related to FA intake (coefficient 0.33 ± 0.13), whereas contribution of bacterial lipid to duodenal flow decreased as FA intake increased. For each FA with 12 to 16 C units, prediction of FA absorption from its respective duodenal flow was linear. For total FA and FA with 18 C units, apparent absorption levelled off at high duodenal flows. All these relationships were discussed according to current knowledge on microbial metabolism in the rumen and on the intestinal digestibility of FA in the intestine.

In ruminants, dietary lipids are extensively hydrogenated by rumen micro-organisms, and the extent of this biohydrogenation is a major determinant of long-chain fatty acid profiles of animal products (milk, meat). This paper reports on the duodenal flows of C18 fatty acids and their absorption in the small intestine, using a meta-analysis of a database of 77 experiments (294 treatments). We established equations for the prediction of duodenal flows of various 18-carbon (C18) fatty acids as a function of the intakes of their precursors and other dietary factors (source and/or technological treatment of dietary lipids). We also quantified the influence of several factors modifying rumen metabolism (pH, forage : concentrate ratio, level of intake, fish oil supplementation). We established equations for the apparent absorption of these fatty acids in the small intestine as a function of their duodenal flows. For all C18 unsaturated fatty acids, apparent absorption was a linear function of duodenal flow. For 18:0, apparent absorption levelled off for high duodenal flows. From this database, with fatty acid flows expressed in g/kg dry matter intake, we could not find any significant differences between animal categories (lactating cows, other cattle or sheep) in terms of rumen metabolism or intestinal absorption of C18 fatty acids.

Four ruminally fistulated Holstein heifers (BW = 264 ± 12 kg) were used in a 4 × 4 Latin square design experiment to determine the effect of increasing levels of sodium bicarbonate (BICARB; 0%, 1.25%, 2.50% and 5%, on concentrate dry matter (DM) basis) on DM intake (DMI), water consumption and ruminal fermentation. Sampling was carried out in the last week of each four 21-day experimental periods. Heifers were offered concentrate (13.4 ± 0.04% crude protein (CP), 13.3 ± 0.44% NDF, 51.7 ± 0.97% starch) and barley straw once daily at 0830 h ad libitum. There was a linear decrease in concentrate DMI and a linear increase in straw DMI with increasing buffer level in the diet, resulting in a tendency towards a linear decrease in total DMI. Intake of concentrate was 6.89, 7.66, 6.72 and 5.72 ± 0.83 kg/day, whereas straw intakes were 0.73, 0.84, 0.94 and 1.06 ± 0.14 kg/day, for the 0%, 1.25%, 2.5% and 5% BICARB, respectively. Water consumption was not affected by treatments when expressed as l/day or percentage of BW, but increased linearly when expressed as l/kg of DMI. The percentage of total daily water drunk in the morning (from 0830 to 1230 h) increased linearly with the level of buffer. Mean ruminal pH and total area under the pH curve were not affected with increasing buffer level. The lowest daily pH (5.65 ± 0.09) was not affected by treatments. A quadratic tendency (P ⩽ 0.10) was observed in the number of hours and the area under the pH curve in which ruminal pH was below 5.8, with high values only at the 0% BICARB. Additionally, increasing bicarbonate level caused a linear increase in the ruminal pH at 2 and 4 h after feeding. Daily average NH3 N (2.4 ± 0.9 mg N/100 ml) and total volatile fatty acids (VFA) (143 ± 12 mM) concentrations were not affected by treatments. Daily average molar proportion of propionate decreased linearly, and acetate proportion and the acetate-to-propionate ratio were increased with increasing buffer level in the diet. Molar percentage of butyrate, isobutyrate and isovalerate, and branched-chain VFA concentration increased linearly as the level of bicarbonate increased in the diet. Results indicate that high levels of BICARB to finishing heifers fed high-concentrate diets may result in a decreased DMI without significant effects on mean ruminal pH, which may affect animal performance. All individual VFA proportions, except valerate, were changed by the addition of bicarbonate.

Four Holstein heifers (264 ± 12 kg initial BW) were used in a 4 × 4 Latin square design with 21-day experimental periods to determine the effect of increasing levels of sodium bicarbonate (BICARB) (0%, 1.25%, 2.5% and 5%, of concentrate dry matter (DM) basis) on chewing and feed intake behavior when fed high-concentrate diets. Concentrate (13.41% CP, 13.35% NDF) and barley straw were fed once a day at 0830 h ad libitum. Feed bunks placed on scales and video recording were used to measure 24-h feed intake and chewing behavior, respectively. The patterns of feeding behavior (feed intake, meal size and length) and chewing behavior (eating, ruminating and total chewing) were studied by dividing the day into 12 intervals of 2-h each, beginning at feeding (interval 1 through 12). Number of meals per day and eating rate decreased linearly with increasing buffer level, but meal length increased linearly. No treatment effects were observed in sum of daily meal lengths or average meal size. The treatment × interval interaction was significant on meal size, length and feed intake. The size and length of those meals occurring during the 4 h post-feeding increased linearly. However, meal size tended to decrease in the evening between 8 and 12 h, whereas feed intake decreased linearly from 6 to 10 h and from 12 to 14 h post-feeding. Buffer concentration did not affect the percentage of time spent ruminating, eating or drinking per day but the buffer level × interval interaction was significant. Time spent eating expressed as min per kg of DM or organic matter (OM) intake increased linearly with buffer levels. Proportion of time spent eating increased linearly during the intervals between 0 and 4 h post-feeding. Time spent ruminating decreased linearly during the 2 h post-feeding, and also in the evening from 12 to 14 h, and at night from 18 to 22 h post-feeding, but the effect was quadratic between 8 and 10 h when intermediate buffer levels showed the greatest ruminating time. Time spent drinking decreased linearly from 6 to 8 h but increased during the 2 h following feeding and from 10 to 12 h post-feeding. Daily eating rate and meal frequency decreased linearly as the buffer level increased, but average meal size and daily chewing times were not affected. However, significant time of the day × buffer level interactions were observed for feed intake, meal size and length and chewing behavior.

Four male pigs (Duroc × Landrace × Yorkshire; average initial (mean ± SEM) BW = 22.5 ± 1.1 kg), fitted with permanent catheters in the portal vein, ileal vein and carotid artery, were used in a 4 × 4 Latin square experimental design to measure the effect of dietary starch sources on the net portal appearance of glucose and amino acids. Dietary starch sources were resistant starch (RS), maize, sticky rice and brown rice. Diets were provided at 0730, 1530 and 2330 h during a 6-day adjustment period and 1-day collection period. On day 7 of each period, blood samples were collected from the portal vein and carotid artery at 0730 h (prior to feeding) and hourly up to 8 h after meal. Blood samples were used to determine glucose, amino acid, packed cell volume and partial pressure of oxygen (pO2). When calculated per 100 g feed intake, cumulative portal glucose appearance was lower (P < 0.05) for resistant starch than for maize, sticky rice or brown rice up to 8 h after the meal. Cumulative portal glucose appearance was higher (P < 0.05) for sticky rice and brown rice than for other diets until 4 h after the meal, but maize had higher cumulative glucose appearance after 4 h. Net cumulative portal concentrations of most amino acids for resistant starch were also reduced (P < 0.05) than for the other starch sources. Cumulative portal appearance of amino acid represented 48.39%, 63.76%, 61.80% and 59.18% of dietary intake for resistant starch, maize, sticky rice and brown rice, respectively. Collectively, our results indicate that dietary starch sources substantially affect the appearance of amino acids and glucose in the portal circulation.

This study examined the effect of a bovine colostrum whey supplementation on growth performance, feed intake, faecal Escherichiacoli population and systemic immune response of piglets at weaning. A total of 96 piglets weaned at 26 ± 2 days of age were assigned for 4 weeks to one of the two treatments: (1) the control (commercial diet with bovine milk whey powder) and (2) the colostrum (commercial diet with freeze-dried bovine colostrum whey) treatments. The two supplements were incorporated in the diet at a level of 20 g/kg during the first 2 weeks after weaning and lowered to a level of 10 g/kg for the next 2 weeks. BW and feed intake were measured weekly. Faecal E. coli counts were determined weekly on specific culture media. Blood samples were collected weekly and submitted to a cell counter analyser for their main components (red and white blood cells, platelets) and flow cytometry was used to determine the lymphocyte population (B, T, Th and Tc). Finally, total seric immunoglobulin (IgM, IgG and IgA) concentrations were determined by the ELISA method. During the first week of the trial, the piglets from the colostrum treatment had improved average daily gain (170 g/day v. 81 g/day, P < 0.001), average daily feed intake (346 g/day v. 256 g/day, P = 0.03) and feed efficiency (BW gain/feed intake) (0.48 v. 0.31, P = 0.04). The pigs fed the colostrum treatment had also a 25% increase in circulating IgA (P = 0.03) compared with the control treatment the first week. It is concluded that a distribution of bovine colostrum whey (20 g/kg diet) during the first week post-weaning induces a systemic IgA response and has a beneficial action on growth performances and feed efficiency.

Compensatory growth, a frequent phenomenon observed in ruminants due to seasonal variation in food availability, affects protein metabolism including protein oxidation. These oxidation processes may have an impact on animal health as well as on meat protein degradation during post mortem aging (ie meat maturation). Sixteen male lambs were randomly divided into four groups. One group was fed ad libitum (C) and one group was food-restricted to 60% of the intake of the C group (R). The last two groups were restricted similarly to the R group and refed either ad libitum (RAL) or similarly to the C group (pair-feeding) (RPF). Muscles samples were taken immediately after slaughter. The present study showed that the restriction/refeeding pattern had no effect on protein oxidation in the muscles studied (longissimus dorsi (LD), semitendinosus (ST) and supraspinatus (SP)). However, total antioxidant capacity decreased after food restriction (−51%, −43%, P < 0.01 for ST and LD muscles, respectively) and re-increased only after ad libitum refeeding. This alteration in the total antioxidant status can partially be explained by the similar pattern of change observed in the glutathione concentration of the muscles (−25%, P < 0.05 for ST muscle and NS for the other muscles). However, none of the concentrations of other water-soluble antioxidants studied (carnosine, anserine, glutathione peroxidase and superoxide dismutase) were altered during compensatory growth. This study showed that an inappropriate feeding level following a nutritional stress induced alterations in the total antioxidant status (particularly that of glutathione), which may have consequences on animal health. Other consequences of a decrease of the animal antioxidant status in vivo could be an alteration of the protein oxidation processes during meat maturation.

The aim of this experiment was to study the kinetics of anti-eCG (equine chorionic gonadotrophin) antibodies in relation to eCG dose (8 or 25 IU) and number of injections (n = 11) in comparison with a control group (no injection), and to relate antibody production to sexual receptivity and productivity of rabbit does. In all, 124 lactating primiparous rabbit does were inseminated every 35 days for a year. Just before eCG injection (48 h before insemination), blood samples were collected from all the does to assay anti-eCG antibodies. The anti-eCG antibody binding rate, regardless of the injected dose, shows that none of the does developed detectable anti-eCG antibodies before the 7th injection. The level of detectable anti-eCG antibodies began to show an increase at the 7th injection and was significant only for the 25 IU dose at the 11th injection. At the end of the experiment, 15% and 39% of does treated with 8 and 25 IU, respectively, developed immunity to eCG (binding rate >6%: higher binding rate of the control group). Consequently, the immune response depends on the eCG dose and on the number of injections. Moreover, productivity of does estimated from the number of weaned rabbits produced per insemination is not influenced by the level of eCG antibodies (7.0 and 6.9 for binding rate <6% and binding rate ⩾6%, respectively). Only 19 inseminations (n = 6 and n = 13 for 8 and 25 IU, respectively) were made on hyperimmune does. Consequently, the immune response to eCG seems to be marginal for rabbit does. Moreover, under the described experimental conditions, reproductive performances of hyperimmune does were not affected.

The objective was to determine the relationship of muscular and skeletal scores taken on the live animal and carcass conformation and fat scores with carcass composition and value. Bulls (n = 48) and heifers (n = 37) of 0.75 to 1.0 late-maturing breed genotypes slaughtered at 16 and 20 months of age, respectively, were used. At 8 months of age (weaning) and immediately pre-slaughter, visual muscular scores were recorded for each animal and additionally skeletal scores were recorded pre-slaughter. Carcass weight, kidney and channel fat weight, carcass conformation and fat scores, fat depth over the longissimus dorsi muscle at the 12th (bulls) or 10th (heifers) rib and carcass length were recorded post-slaughter. Each carcass was subsequently dissected into meat, fat and bone using a commercial dissection procedure. Muscular scores taken pre-slaughter showed positive correlations with killing-out rate (r ≈ 0.65), carcass meat proportion (r ≈ 0.60), value (r ≈ 0.55) and conformation score (r ≈ 0.70), and negative correlations with carcass bone (r ≈ −0.60) and fat (r ≈ −0.4) proportions. Corresponding correlations with muscular scores at weaning were lower. Correlations of skeletal scores taken pre-slaughter, carcass length and carcass weight with killing-out rate and the various carcass traits were mainly not significant. Carcass fat depth and kidney and channel fat weight were negatively correlated with carcass meat proportion and value, and positively correlated with fat proportion. Correlations of carcass conformation score were positive (r = 0.50 to 0.68) with killing-out rate, carcass meat proportion and carcass value and negative with bone (r ≈ −0.56) and fat (r ≈ −0.40) proportions. Corresponding correlations with carcass fat score were mainly negative except for carcass fat proportion (r ≈ 0.79). A one-unit (scale 1 to 15) increase in carcass conformation score increased carcass meat proportion by 8.9 and 8.1 g/kg, decreased fat proportion by 4.0 and 2.9 g/kg and decreased bone proportion by 4.9 and 5.2 g/kg in bulls and heifers, respectively. Corresponding values per unit increase in carcass fat score were −11.9 and −9.7 g/kg, 12.4 and 9.9 g/kg, and −0.5 and −0.2 g/kg. Carcass conformation and fat scores explained 0.70 and 0.55 of the total variation in meat yield for bulls and heifers, respectively. It is concluded that live animal muscular scores, and carcass conformation and fat scores, are useful indicators of carcass meat proportion and value.

Fifteen nulliparous and nine multiparous Serrana goats were used, through two successive oestrous cycles, in order to characterize their ovulation time with regard to the number of ovulations after induced and natural oestrus during the breeding season. The onset of oestrus was detected by the amount of vasectomized bucks after oestrus synchronization with prostaglandin, given 10 days apart, and in the following two expected natural oestrus. The preovulatory LH peak was determined from blood samples collected 0, 4, 8, 12, 16, 20 and 24 h after onset of oestrus. A transrectal ovarian ultrasound scanning was performed 20, 24, 28, 32, 36, 40, 44 and 60 h after onset of oestrus, for the detection of ovulations by means of the disappearance of large follicles (>4 to 5 mm). Single ovulations were observed in 76% of oestrous periods in nulliparous goats and in 18% of nulliparous goats. The onset of oestrus to LH peak interval was lower in nulliparous (12.1 ± 0.9 h, n = 38) than in multiparous (15.6 ± 1.0 h, n = 22, P < 0.05) goats with no oestrus interaction effects (P > 0.05). The LH peak to first ovulation interval was higher after natural (18.9 ± 0.7 h, n = 36) than after induced (15.8 ± 1.2 h, n = 24, P < 0.05) oestrus. The onset of oestrus to total ovulation interval was influenced by parity (P < 0.01) and oestrus type (P < 0.05) with a length of 30.1 ± 1.1 h (n = 15) and 33.4 ± 1.5 h (n = 9) for induced oestrus of nulliparous and multiparous goats, respectively, and 32.5 ± 1.0 h (n = 23) and 36.5 ± 1.1 h (n = 13) for natural oestrus of nulliparous and multiparous goats, respectively. The onset of oestrus to first ovulation interval was not influenced by parity, but an interval of 8.0 ± 1.6 h was observed between the first and second ovulations in polyovulatory oestrus. Consequently, nulliparous goats that are predominantly monovular ovulate earlier than multiparous goats that are predominantly polyovulatory. In conclusion, significant differences occurred in the number and time of ovulations between nulliparous and multiparous goats. More research is necessary for a deeper understanding of the mechanisms regulating monovularory and polyovulatory oestrous cycles regarding the parity of goats.

Wood-chip pads represent a low-cost alternative to housing for cattle during the winter. Considering the negative welfare implications associated with housing indoors on concrete, they may also offer welfare benefits to replacement dairy heifers. However, these animals may not be able to withstand winter weather conditions on a grass silage diet. The aim of this experiment was to evaluate behaviour, limb injuries, dirtiness scores, performance and climatic energy demand (CED) of yearling dairy heifers on two levels of nutrition kept outdoors on a wood-chip pad or indoors in cubicles during the winter. Ninety-six 10-month-old heifers were blocked and assigned in groups of eight, to one of the following four treatments in a 2 × 2 factorial design: (a) indoors, silage only; (b) indoors, silage plus concentrate; (c) outdoors, silage only; and (d) outdoors, silage plus concentrate. There were three replicate groups per treatment. All animals were inspected for skin lesions and were weighed and body condition scored (BCS) at the beginning and end of the trial. Instantaneous scan sampling and continuous all-occurrence behaviour sampling were used to collect behaviour data during two 24-h periods. Animals were also dirtiness scored and group feed intakes were recorded during the trial. Significantly more comfort, social and play behaviours were recorded outdoors (P < 0.05) while trips, slips and falls were only recorded indoors (P < 0.001). Groups outdoors had significantly lower limb lesion scores at the end of the experiment (P < 0.05) and fewer groups outdoors were affected by all categories of limb lesions. However, they were consistently dirtier than animals indoors (P < 0.001). Low-nutrition animals had lower feed intakes, smaller BCS changes and lower average daily weight gains than high-nutrition animals (P < 0.01). Heifers outdoors had significantly lower average daily weight gains and BCS changes (P < 0.05) explained by lower feed intakes (P < 0.01). However, outdoor heifers on both the high- and low-nutrition diets and indoor animals on the low-nutrition diet had lower UFL (feed unit for maintenance and lactation (Irish Republic)) intakes (−0.36, −0.35 and −0.22, respectively) than that required to meet the daily live-weight gains they achieved. Heifers indoors on the high-nutrition diet gained 0.98 kg per day but consumed 0.17 UFL more than what would be recommended to achieve a daily weight gain of 1.0 kg. The CED for outdoor heifers was higher than that of indoor heifers (6.18 v. 5.47 MJ/day per m2 body surface area; P < 0.001, s.e.d. 0.044). However, CED did not exceed heat production in any treatment. Although animal performance was reduced outdoors, the wood-chip pad was associated with welfare benefits compared with cubicle housing.

A study was conducted to evaluate the effect of pre-weaning concentrate feeding in early-weaned (EW, day 90) or traditionally weaned (TW, day 150) autumn-born beef calves on growth, feed intake and feed efficiency, and carcass and meat quality. Twenty-eight male calves were either EW or TW, and offered a starter concentrate (S) or no additional feed (NS) during the pre-weaning period. Therefore, four management strategies were tested: EWS, EWNS, TWS and TWNS. Growth patterns were affected by management strategy. From day 90 to 150, TWNS calves presented a substantially lower average daily gain (ADG) than their counterparts, which had similar performance. During the finishing phase (from day 150 to slaughter at 450 kg live weight), EWS calves had the lowest ADG. Daily feed intake or efficiency in the finishing phase was unaffected by previous management. Serum IGF-I concentrations at day 90 and slaughter did not differ with management strategy, but early weaning and pre-weaning concentrate feeding increased IGF-I concentrations at day 150. Circulating leptin concentrations were unaffected by age at weaning and pre-weaning concentrate feeding, except for leptin concentrations at slaughter, which were higher in S calves than in NS calves. Total concentrate intake from birth to slaughter and the concomitant feed costs were higher for EWS and EWNS calves than for TWNS and TWS ones. However, cow feed costs were lower for cows whose calves had been early weaned. Concerning carcass quality, early weaning improved dressing percentage and increased fatness score, and particularly TWNS calves presented a poorer conformation. Meat quality was not affected by management strategy. Considering the economic performance, TWS, EWNS and EWS strategies yielded a similar economic margin, whereas TWNS would be the least advisable strategy when calves are fattened in the farm until slaughter.

The objective of this study was to test whether the use of tannin-rich shrub legume forage is advantageous for methane mitigation and metabolic protein supply at unchanged energy supply when supplemented in combination with tannin-free legumes to sheep. In a 6 × 6 Latin-square design, foliage of two tannin-rich shrub legume species (Calliandra calothyrsus and Flemingia macrophylla) were used to replace either 1/3 or 2/3, respectively, of a herbaceous high-quality legume (Vigna unguiculata) in a diet composed of the tropical grass Brachiaria brizantha and Vigna in a ratio of 0.55 : 0.45. A Brachiaria-only diet served as the negative control. Each experimental period lasted for 28 days, with week 3 serving for balance measurement and data collection inclusive of a 2-day stay of the sheep in open-circuit respiration chambers for measurement of gaseous exchange. While Vigna supplementation improved protein and energy utilisation, the response to the partial replacement with tannin-rich legumes was less clear. The apparent total tract digestibilities of organic matter, NDF and ADF were reduced when the tannin-rich plants partially replaced Vigna, and the dose–response relationships were mainly linear. The tannin-rich plants caused the expected redistribution of more faecal N in relation to urinary N. While Flemingia addition still led to a net body N retention, even when fed at the higher proportion, adding higher amounts of Calliandra resulted in body protein mobilisation in the growing lambs. With respect to energy, supplementation of Vigna alone improved utilisation, while this effect was absent when a tannin-rich plant was added. The inclusion of the tannin-rich plants reduced methane emission per day and per unit of feed and energy intake by up to 24% relative to the Vigna-only-supplemented diet, but this seems to have been mostly the result of a reduced organic matter and fibre digestion. In conclusion, Calliandra seems less apt as protein supplement for ruminants while Flemingia could partially replace a high-quality legume in tropical livestock systems. However, methane mitigation would be small due to associated reductions in N and energy retention.

Dietary linseed supply efficiently elevates the linolenic acid concentration of pork. The main problem of increasing the n-3 fatty acid tissue levels arises from a higher susceptibility to lipid oxidation. Increasing the saturation level of tissue lipids by the dietary inclusion of conjugated linoleic acids (CLA) or tallow might prevent oxidation. Thus, the aim of the study was to evaluate the impact of dietary CLA or tallow supplementation combined with extruded linseed on the growth performance, carcass characteristics and fatty acid profile of muscles (longissimus, semimembranosus, biceps femoris) and subcutaneous fat (SF). The enzyme activity of the de novo lipogenesis and stearoyl-CoA desaturase in the SF was also assessed. From 18 to 104 kg BW, 32 Swiss Large White barrows were fed a diet supplemented with either: (1) 2% linseed (L2); (2) 3% linseed (L3); (3) 2% linseed + 1% CLA (L2-C) or (4) 2% linseed + 1% tallow (L2-T). The linolenic and eicosatrienoic acid concentrations were higher (P < 0.01) and the ∑n-6/∑n-3 ratio was lower (P < 0.01) in all tissues of L3 than L2 and L2-T barrows. Only in the SF the docosapentaenoic acid concentration was increased (P < 0.01) in L3 barrows. Compared with the other three diets, feeding the L2-C diets increased (P < 0.01) the amount of myristic, palmitic, stearic and palmitoleic acid at the expense of the oleic and eicosenoic acid content in the intramuscular and SF lipids. Except for the lower (P < 0.05) eicosadienoic acid concentration in the muscles, feeding the L2-C treatment resulted in similar polyunsaturated fatty acid concentrations and ∑n-6/∑n-3 ratio than feeding L2 or L2-T diets. Both the c9,t11- and t10,c12-CLA isomers found in the CLA-supplemented diet were also detected in the tissues, but the c9,t11-isomer was more abundant than the t10,c12-isomer. De novo lipogenesis was not (P > 0.05) affected by the dietary fats, whereas Δ9-desaturase activity was depressed (P < 0.05) by CLA inclusion (L2-C). Only when oxidation was challenged by cooking and subsequent storage for 4 days at 4°C values of thiobarbituric acid-reactive substances were lower (P < 0.05) in longissimus muscle chops of L2-C compared with L2, L3 and L2-T barrows. The present findings revealed that CLA, but not tallow, combined with extruded linseed enhanced the oxidative stability of pork probably by lowering the degree of unsaturation of the lipids without affecting the improved ∑n-6/∑n-3 ratio.