Feeding n-3 long-chain polyunsaturated fatty acids (LCPUFA) to gilts or sows has shown different responses to litter growth, pre-weaning mortality and subsequent reproductive performance of the sow. Two hypotheses were tested: (1) that feeding a marine oil-based supplement rich in protected n-3 LCPUFAs to gilts in established gestation would improve the growth performance of their litters; and (2) that continued feeding of the supplement during lactation and after weaning would offset the negative effects of lactational catabolism induced, using an established experimental model involving feed restriction of lactating primiparous sows. A total of 117 primiparous sows were pair-matched at day 60 of gestation by weight, and when possible, litter of origin, and were allocated to be either control sows (CON) fed standard gestation and lactation diets, or treated sows (LCPUFA) fed the standard diets supplemented with 84 g/day of a n-3 LCPUFA rich supplement, from day 60 of first gestation, through a 21-day lactation, and until euthanasia at day 30 of their second gestation. All sows were feed restricted during the last 7 days of lactation to induce catabolism, providing a background challenge against which to determine beneficial effects of n-3 LCPUFA supplementation on subsequent reproduction. In the absence of an effect on litter size or birth weight, n-3 LCPUFA tended to improve piglet BW gain from birth until 34 days after weaning (P = 0.06), while increasing pre-weaning mortality (P = 0.05). It did not affect energy utilization by the sow during lactation, thus not improving the catabolic state of the sows. Supplementation from weaning until day 30 of second gestation did not have an effect on embryonic weight, ovulation rate or early embryonic survival, but did increase corpora lutea (CL) weight (P = 0.001). Eicosapentaenoic acid and docosahexaenoic acid (DHA) levels were increased in sow serum and CL (P < 0.001), whereas only DHA levels increased in embryos (P < 0.01). In conclusion, feeding n-3 LCPUFA to gilts tended to improve litter growth, but did not have an effect on overall subsequent reproductive performance.

On 1 January 2005, the direct support schemes directed at UK livestock farmers as part of the Common Agricultural Policy (CAP) were replaced with a Single Farm Payment, decoupled from production. In practical term, this means that farmers now have freedom of choice over the particular farm enterprises they engage in since their income support is no longer dependent on their type of production. Farmer policy-response will be dependent on their previous dependence on the direct subsidies being replaced, which, as the paper shows, is considerable for UK livestock farmers. The paper suggests a dichotomous shift of farmer objective in the livestock sector in the future, with ‘environmental managers’ and ‘market managers’ focusing on different outputs. The outcome will be a significant down-sizing of the UK livestock sector but with probable net gains to the environment.

To better understand the mechanisms that allow some animals to sustain their productive effort in harsh environmental conditions, rabbit does from two selection lines (LP and V) were housed in normal (NC), nutritional (NF) or heat (HC) challenging environmental conditions from first to third partum. The LP line (n=85) was founded on reproductive longevity criteria by selecting does from commercial farms that had a minimum of 25 partum with more than 7.5 kits born alive per parity. Line V (n=79) was constituted from four specialised maternal lines into a composite synthetic line and then selected by litter size at weaning for 36 generations. Female rabbits in NC and NF environments were housed at normal room temperature (18°C to 24°C) and fed with control [11.6 MJ digestible energy (DE)/kg dry matter (DM)] or low-energy diets (9.1 MJ DE/kg DM). HC does were housed at high room temperatures (25°C to 35°C) and fed the control diet. Female rabbits in the HC and NF environments ingested 11.5% and 6% less DE than NC does, respectively (P<0.05). These differences between environments occurred in both lines, with the differences being higher for LP than for V does (+6%; P<0.05). Milk yield responses followed those of energy intake also being higher for LP does (+21.3 g/day; P<0.05). The environmental conditions did not affect the perirenal fat thickness (PFT), but a genotype by environment interaction was observed. In NC and HC, the PFT was higher for line V (+0.23 and +0.35 mm, respectively; P<0.05) than for LP does, but this was not the case at NF (−0.01 mm). Moreover, the PFT evolution was different between them. In the NC environment, LP does used the accreted PFT in late lactation (−0.29 mm), whereas V does did not (−0.08 mm). Conversely, in the HC environment, LP does showed a flat PFT evolution in late lactation, whereas V does accumulated PFT. In the NF environment, LP and V does had a similar PFT evolution. There was also a litter size reduction for V does of −2.59 kits total born in HC and −1.78 kits total born in NF environments, whereas this was not observed for LP does. The results for LP does indicate a direct use of DE ingested for reproduction with little PFT change, whereas V does actively use the PFT reserves for reproduction.

Light intensity, spectrum and pattern may affect laying hen behaviors and production performance. However, requirements of these lighting parameters from the hens’ standpoint are not fully understood. This study was conducted to investigate hens’ needs for light intensity and circadian rhythm using a light tunnel with five identical compartments each at a different fluorescent light intensity of <1, 5, 15, 30 or 100 lux. The hens were able to move freely among the respective compartments. A group of four W-36 laying hens (23 to 30 weeks of age) were tested each time, and six groups or replicates were conducted. Behaviors of the hens were continuously recorded, yielding data on daily time spent, daily feed intake, daily feeding time, and eggs laid under each light intensity and daily inter-compartment movement. The results show that the hens generally spent more time in lower light intensities. Specifically, the hens spent 6.4 h (45.4%) at 5 lux, 3.0 h (22.1%) at 15 lux, 3.1 h (22.2%) at 30 lux and 1.5 h (10.3%) at 100 lux under light condition; and an accumulation of 10.0 h in darkness (<1 lux) per day. The 10-h dark period was distributed intermittently throughout the day, averaging 25.0±0.4 min per hour. This hourly light-dark rhythm differs from the typical commercial practice of providing continuous dark period for certain part of the day (e.g. 8 h at night). Distributions of daily feed intake (87.3 g/hen) among the different light conditions mirrored the trend of time spent in the respective light intensity, that is, highest at 5 lux (28.4 g/hen, 32.5% daily total) and lowest at 100 lux (5.8 g/hen, 6.7%). Hen-day egg production rate was 96.0%. Most of the eggs were laid in <1 lux (61.9% of total) which was significantly higher than under other light intensities (P<0.05). Findings from this study offer insights into preference of fluorescent light intensity by the laying hens. Further studies to assess or verify welfare and performance responses of the hens to the preferred lighting conditions and rhythm over extended periods are recommended.

The objectives of this study were to analyze whether dry matter intake (DMI), water intake (WI) and BW were influenced by estrus. A second objective was to determine whether correlations exist among these traits in non-estrous days. Data collection included 34 Holstein-Friesian cows from the research farm ‘Haus Riswick’ of the Agricultural Chamber North Rhine-Westphalia, Germany. On an individual basis, daily DMI and daily WI were measured automatically by a scale in the feeding trough and a WI monitoring system, respectively. BW was determined by a walk-through scale fitted with two gates – one in front and one behind the scale floor. Data were analyzed around cow’s estrus with day 0 (the day of artificial insemination leading to conception). Means during the reference period, defined as days −3 to −1 and 1 to 3, were compared with the means during estrus (day 0). DMI, WI and BW were affected by estrus. Of all cows, 85.3% and 66.7% had reduced DMI and WI, respectively, on day 0 compared with the reference period. Lower BW was detected in 69.2% of all cows relative to the reference period. During the reference period, average DMI, WI and BW were 23.0, 86.6 and 654.8 kg. A minimum DMI of 20.4 kg and a minimum BW of 644.2 kg were detected on the day of estrus, whereas the minimum WI occurred on the day before estrus. After estrus, DMI, WI and BW returned to baseline values. Intake of concentrated feed did not seem to be influenced by estrus. Positive correlations existed between daily DMI and daily WI (r=0.63) as well as between cows’ daily BW and daily WI (r=0.23). The results warrant further investigations to determine whether monitoring of DMI, WI and BW may assist in predicting estrus.

Data were obtained on 3028 lambs born during five successive years from 1961 to 1966 at Ras El-Hekma Desert Research Station in the Western Coastal Egyptian Desert. Breed groups involved in the study were Hungarian Merino, Syrian Awassi, native Barki sheep, and nine of their crosses. The characters studied were birth weight, weaning and yearling weights, pre- and post-weaning average daily gain and yearling greasy fleece weight. The effects of breed group, year of birth, sex, age of dam and type of birth on these characters were investigated.

The results obtained showed that Barki lambs excelled Merino lambs in all the traits related to body growth. Merino lambs, on the other hand, excelled Barkis in fleece weight. Barki lambs also excelled Awassi lambs in all traits except birth and weaning weights. In all characters except pre-weaning gain, the first cross of Merino and Barki (½M½B) was markedly superior to all the other crosses and pure breeds. The two third-crosses, ⅜ M ⅝ B and ⅝ M ⅜ B, were similar to each other in their productive traits and were slightly inferior to the first cross. The two back-crosses, ¼M¾B and ¾M¼B, were markedly different from each other, the former being better than the latter. The three-eighths Merino group is suggested for developing a new strain of sheep for the semi-arid regions. The effects of the environmental factors on the six characters studied were all highly significant except for the effect of sex on fleece weight and the effects of age of dam and type of birth on growth from weaning to yearling ages. The most important factor affecting the different traits was year of birth. Type of birth and age of dam were important sources of variation only for the characters studied till weaning age, but became of little importance thereafter. The effect of sex was pronounced only on yearling weight.

The development of analytical methods to verify the production system of meat products requires the identification of biomarkers that can trace the product’s origin, and secondly the factors that govern the deposition of these markers in animal tissue need to be defined. In this study, 2,3-octanedione, skatole and terpenes were selected as biomarkers, and their deposition was investigated in bull calves reared under three different strategies. All of the animals were reared indoors until approximately 150 days of age. They were suckled twice a day by their mothers, and both calves and cows had free access to cocksfoot hay. Then the first two groups of animals were kept indoors, suckled by their mothers twice a day and received either cocksfoot hay (HL) or freshly cut-green herbage (GL) and a limited quantity of concentrate. The third group of calves (PH) was kept on pasture with their mothers and offered concentrate ad libitum. The pasture supporting the PH animals was highly diversified, containing several terpene-rich plant species, whereas the herbage for the GL animals contained no species known to be aromatic. Perirenal and subcutaneous adipose tissues were analysed for volatile compounds. The perirenal fat was found to be more responsive to the treatment and a more reliable substrate than the subcutaneous adipose tissue. Higher levels of 2,3-octanedione (P < 0.05) were found in PH and GL than in HL fat (6.56, 6.51 and 5.77 area arbitrary units, respectively, in perirenal fat), confirming the ability of this molecule to trace green herbage feeding. Skatole was detected in the perirenal and subcutaneous fat of all the animals. Animals receiving high concentrate level (PH group) presented lower (P < 0.05) skatole values (5.83 area arbitrary units in perirenal fat) than animals receiving low concentrate level (HL and GL groups, 6.23 and 6.71 area arbitrary units, respectively, in perirenal fat). Terpenoids, and especially sesquiterpenes, were found at higher levels and diversities in the PH than in the GL and HL animals. Two monoterpenoids allowed group discrimination considering perirenal or subcutaneous fat without distinction, whereas 11 and 5 sesquiterpenoids from perirenal and subcutaneous fat, respectively, allowed it.

An experiment was carried out to study the effect of adding α-galactosidase to the diet on the performance and digestive parameters of growing-finishing pigs. Fifty-four gilts, average body weight (BW) of 43 (s.e. 0·4) kg, were allocated to 18 pens and used in a production experiment divided in two consecutive periods of 28 days each (growing and finishing). In each period gilts were given a diet based on cereals, soya-bean meal and peas, supplemented (Enzyme) or unsupplemented (Control) with 200 units per kg of α-galactosidase. All diets included 2 g Cr2O3 per kg as a digestibility marker. Food intake and body weight were recorded every 2 weeks and faecal samples by pen were collected at the end of each period. Average daily gain (ADG), food: gain ratio and faecal digestibility of dry matter (DM), crude protein (CP) and neutral-detergent fibre (NDF) were calculated. At the end of the production experiment nine gilts from each treatment were selected and given the finishing diet for a further 10 days before being slaughtered. Samples of digesta from the ileum and caecum were collected and ileal digestibility of monosaccharides determined. Short chain volatile fatty acids (SCVFA ) and purine bases (PB) in caecal digesta were analysed. The use of α-galactosidase improved the ADG (P < 0·01) and the food: gain ratio (P < 0·01) simultaneous to increases in the faecal digestibility of DM (P < 0·05), CP (P < 0·05) and NDF (P = 0·07) in the finishing period. Alpha-galactosidase supplementation also improved the ileal digestibility of some monosaccharides (galactose, rhamnose, mannose and fucose) of the dietary fibre fraction (P < 0·05); and reduced total caecal concentration of SCVFA (P = 0·15), proportion of branched-chain VFA (P < 0·001), and concentration of total PB (P < 0·001). It is concluded that adding α-galactosidase to a cereal-soya-bean meal-pea diet improves ADG, food: gain ratio and digestibility in fattening pigs, and reduces the amount of fermentable substrate flowing to the large intestine.

The effects of xylanase and antibiotic addition to the diet, and the use of HCl-insoluble ash as a marker, on ileal and faecal apparent digestibilities of nutrients were studied with 12 growing pigs fitted with post-valvular T-caecum cannulae (PVTC). The results showed that the apparent ileal digestibility of non-starch polysaccharide (NSP) was high, (over 0·30). Xylanase, or antibiotics (Avoparcin) or xylanase plus antibiotics supplementation of the wheat middling-based diets did not significantly (P > 0·05) increase the ileal and faecal apparent digestibilities of NSP, neutral-detergent fibre (NDF), dry matter, crude protein, energy or amino acids. There were no significant (P > 0·05) differences between the HCl-insoluble ash and Cr2O3 recoveries at the ileal or at the faecal levels: proportionately, 0·864 and 0·911 for the ileal and faecal recoveries of HCl-insoluble ash, and 0·857 and 0. 915 for the ileal and faecal recoveries of Cr2O3, respectively.

Four sheep (live weight 39 to 42 kg) fitted with rumen cannulas were offered ammonia-treated barley straw alone (control) or supplemented with unmolassed sugar-beet pulp or rolled barley at 0·20 or 0·40 of the total diet on a fresh weight basis (SBP20, SBP40, B20 and B40, respectively) using a 4 × 5 randomized block design. Total diet intakes were 710, 873, 1054, 843 and 1021 g dry matter per day for control, SBP20, SBP40, B20 and B40 respectively. The intake of straw was depressed significantly with SBP40 and B40 (P < 0·05). Rumen pH and ammonia concentration decreased, and total volatile fatty acid concentrations increased (P < 0·05) with increasing level of supplementation for both supplements. Rumen liquid outflow rate was affected little by the supplementation although this measurement for B40 was significantly higher than that for the other treatments. Microbial protein supply, estimated from urinary excretion of purine derivatives, increased significantly with the increasing amounts of supplements (4·5, 6·7, 8·5, 7·1 and 9·0 (s.e.d. 0·73) g N per day for control, SBP20, SBP40, B20 and B40 respectively) (P < 0·05). The calculated efficiency of microbial protein production was 12·8, 14·2, 14·3, 15·7 and 14·5 (s.e.d. 1·45) g N per kg digestible organic matter intake (DOMI) for the five treatments. Although this value was lowest with the control, differences between treatments were not significant (P > 0·05). It seems that microbial protein yield per unit DOMI for a diet based on ammonia-treated straw could not be improved substantially by supplementation with sugar-beet pulp or barley.

The effects of age and breed on carcass and muscle characteristics of cull cows slaughtered at the same fattening state between 4 and 9 years of age were analysed in four French breeds: Aubrac (AU), Charolais (CH), Limousin (LI), and Salers (SA). Muscle characteristics were determined in three muscles: longissimus thoracis (LT), semitendinosus (ST) and triceps brachii (TB). They included: (1) the % frequency, cross-sectional area and % area of the different fibre types classified according to their contraction rate and metabolic properties (slow twitch oxidative (SO), fast twitch oxidative glycolytic (FOG) and fast twitch glycolytic (FG)), (2) the isocitrate dehydrogenase (ICDH) and lactate dehydrogenase (LDH) activities, representative of oxidative and glycolytic metabolism respectively, and (3) the total and insoluble collagen contents. Whatever the age of the animals at slaughter, the same carcass composition, fibre characteristics (% frequency, area, % area) and metabolic enzyme activities were obtained whatever the muscles considered. In contrast, important differences between breeds were observed in carcass composition (muscle, fat, bone) and enzyme activities. CH cows presented the highest final live weight and LI carcasses were characterized by higher muscle weight, lower fat and bone weights and more glycolytic muscles. Among the muscle characteristics, collagen was the most influenced by age and breed in a breed and muscle dependent manner respectively. AU and LI cows exhibited lower total and insoluble collagen contents than CH and SA cows, particularly at 6 to 7 years of age and for the LT and ST muscles. Thus collagen could explain an important part of the variability in meat quality from cull cows. In conclusion, results of this study provide consistent data on muscle characteristics of cull cows, few studies were available until then.

Growing pigs fitted with post-valve T-caecum cannulas were used in a change-over design experiment (5 ✕ 5) to determine the ileal and total tract apparent digestibility and hindgut disappearance of dietary components and energy in a cassava root and soya-bean meal-based diet with an inclusion rate at 0·15 of the dry matter (DM) of either cassava leaf meal, ensiled cassava leaves, groundnut foliage, or leucaena leaves.

The ileal and total tract apparent digestibilities of organic matter (OM), crude protein, nitrogen-free extractives and energy of the diets were significantly reduced with inclusion of the foliages (P < 0·05). The digestibility of neutral-detergent fibre (NDF) and crude fibre was improved when groundnut foliage was included in the diet (P < 0·05).

The dietary content of NDF was a better predictor of the total tract digestibility of OM (R2 = 0·87) and energy (R2 = 0·90) than the content of crude fibre (R2 = 0·68 for OM digestibility and R2 = 0·72 for energy digestibility).

The disappearance of OM and energy in the hindgut of the foliage diets was 0·36 (s.d. 0·02) and 0·31 (s.d. 0·02), respectively, which was significantly lower (P < 0·05) than on the control diet (0·48 and 0·46, respectively).

Ileal as well as total tract digestibilities of OM in groundnut foliage were higher than for the other leaf products (ileal, 0·55 and 0·42; and total tract, 0·64 and 0·55, respectively). For foliage products of cassava and leucaena an average digestible energy value of 11·4 MJ/kg DM was calculated, whereas for groundnut foliage the corresponding value was 10·9 MJ/kg DM.

It was concluded that, inclusion of foliages in pig diets will reduce the dietary energy content, due to a high fibre content. However, under tropical conditions foliage at low levels of inclusion may be useful in low fibre diets for growing pigs to improve the dietary protein supply.

Groups of 12 spring-calving cows and their calves were allocated to each of three continuous grazing treatments: cows and calves grazed a 4- to 5-cm sward (LI), cows grazed a 4- to 5-cm sward and their calves grazed an 8- to 10-cm sward (Lh) and cows and calves grazed an 8- to 10-cm sward (Hh). In each case cows and calves grazed separately. Sward height had a large effect on both cow and calf performance and intake. The short swards reduced cow herbage intake proportionately by 0·2 compared with that of the taller sward. Cow live-weight gains were −0·60, −0·59 and 0·42 (s.e.d. 0·103) kg/day on treatments LI, Lh and Hh respectively while calf live-weight gains were 0·80, 0·95 and 1·14 (s.e.d. 0·040) kg/day. Calf milk intakes were 7·05, 5·78 and 9·34 (s.e.d. 0·508) kg/day respectively while daily herbage intakes were 17·2, 22·0 and 19·8 (s.e.d. 1·35) g organic matter per kg live weight for treatments LI, Lh and Hh. There was a negative association between calf herbage and milk organic matter intakes in the treatments where the calves had access to a more generous sward height (treatments Lh and Hh), the regression coefficient being −0·89 (s.e. 0·381), indicating the calves' ability to increase herbage intake in response to a reduction in milk intake. On the LI treatment there was no significant relationship between milk and herbage intakes. The ability of grazing suckled calves to compensate for a reduction in milk intake is thus dependent on sward conditions, and may also depend on herbage digestibility. The increase in herbage intake cannot however compensate fully for a restriction in milk supply.

The hypothesis of the research was the assumption, that manganese nanoparticles can affect the body in the same way as macromolecules. Their smaller size and greater biological reactivity will potentially allow the Mn addition to the diet to be reduced and, consequently, less excretion of this element into the environment. The aim of the study was to determine whether the use of Mn nanoparticles would make it possible to reduce the level of this micronutrient added to turkey diets without adversely affecting redox reactions in cells and epigenetic changes. The experiment was conducted on six groups with 10 replications, in a two-factor design with three dosages of manganese: 100, 50 and 10 mg/kg, and two sources: manganese oxide (MnO) and manganese nanoparticles (NP-Mn2O3). Markers of oxidative stress determined in the blood, that is, the concentration of lipid hydroperoxides, malondialdehyde, protein carbonyl derivatives, 3-nitrotyrosine, 8-hydroxydeoxyguanosine, total glutathione, superoxide dismutase, glutathione peroxidase, catalase, ceruloplasmin, total antioxidant status, albumin and vitamin C content. The level of epigenetic changes in the blood was determined by analysing global DNA methylation. In the experiment, in which the diet of turkeys was supplemented with two forms of Mn (MnO or NP-Mn2O3) at three dosages: 100, 50 and 10 mg/kg, the 10 mg/kg dose, especially in the form of NP-Mn2O3, induced lipid oxidation reactions to the greatest extent. Irrespective of the dosage of Mn in the turkey diet, Mn in the form of NP-Mn2O3 was found to reduce protein nitration more than Mn in the form of MnO. Reducing the Mn dosage in the diet from 100 to 50 mg/kg and then to 10 mg/kg is unfavourable because proportionally increases protein and DNA oxidation in cells, decreases the activity of antioxidant enzymes, and increases the level of glutathione. Reducing the dosage from 100 to 10 mg/kg increases global DNA methylation. The reduction of the Mn level, regardless of the form used, is disadvantageous, because it weakens the defense of the antioxidant system, which consequently can induce oxidative processes in the cells. Although Mn in the form of NP-Mn2O3 reduce protein nitration better than in MnO form, the use of manganese nanoparticles in turkey feeding (even in lower doses) requires further study.

Four groups of 10 gilts were reared from an early age under four social conditions. The mating rate (the number of successful copulations as a proportion of oestruses) at the pubertal oestrus of gilts reared in isolation from boars was significantly lower than that of gilts reared near mature boars (P> 0·01). In addition, gilts isolated from boars during rearing had a significantly longer interval from the first mounting attempt by the boar until the display of the standing response (P<0·05) and a significantly higher proportion of these gilts were restless during copulation and terminated the copulation in comparison with gilts reared near mature boars (P<0·01). All gilts were ovariectomized after puberty or at 35 weeks of age and, following a standard oestrogen treatment, they were induced into a series of behavioural oestruses. There were no significant differences between the treatments in the mating rate at these oestruses. It is concluded that the social environment during rearing will influence the mating rate of the gilt at the pubertal oestrus.

In two experiments involving ovariectomized Scottish Blackface ewes and steroid replacement therapy, the effects of level of food intake and of body condition on hypothalamic and pituitary sensitivity to progesterone and oestradiol feedback were investigated. In experiment 1, groups of 16 ewes in similar levels of body condition were given dried grass pellets ad libitum (mean dry-matter (DM) intake of 2481 (s.e. 71) g per head per day; group H) or 1105 g DM per head per day (group M). In experiment 2, groups of 16 ewes were fed so that they achieved body condition scores of 2·70 (s.e. 0040; group HBC) or 1·67 (s.e. 0·036; group LBC) prior to the start of the experiment. All ewes were then fed to maintain their respective levels of body condition. In both experiments, all ewes were ovariectomized and intravaginal progesterone pessaries and subcutaneous oestradiol implants were inserted; these were designed to induce circulating concentrations of these steroids within the normal range for intact ewes. Approximately 1 week later, blood samples were collected at 15-min intervals for 10 h, and at 10-min intervals for 8 h before and after pessary withdrawal respectively. All samples were assayed for LH and selected samples were assayed for FSH and progesterone. Gonadotropin profiles were also recorded during 2-h periods following injection (i.v.) of 0·25 μg and 5 μg GnRH. When circulating progesterone concentrations were elevated, due to the presence of a progesterone pessary, there was no effect of level of food intake on mean LH or FSH concentrations or mean LH pulse frequency but H ewes had a higher mean LH pulse amplitude than M ewes (P < 005). When the progesterone pessaries were absent, H ewes had a higher mean LH concentration (P < 001), mean LH pulse frequency (P < 001) and LH pulse amplitude (P < 0·01) than M ewes but mean FSH concentrations were similar in the two groups. Irrespective of the presence or absence of elevated progesterone concentrations, the pituitary responses to GnRH injection were either not significantly different or were lower in H compared with M ewes. In experiment 2, HBC ewes had a higher mean LH concentration (P < 001), LH pulse frequency (P < 0·001), pulse amplitude (P < 0·001) and FSH concentration (P < 001) than LBC ewes, irrespective of circulating progesterone concentrations. The mean heights and ‘areas’ of the LH peak induced by injection of 0·25 μg GnRH were larger in HBC than LBC ewes (P < 005) irrespective of circulating progesterone concentrations. When mean concentrations before injection were taken into account, the corresponding increases in FSH concentration were similar for the two groups. Following injection of 5 u.g GnRH, the differences in peak size were generally not significant. It is concluded that during the follicular phase of the cycle, a low level of intake is associated with increased hypothalamic sensitivity, but not pituitary sensitivity to oestradiol feedback. Body condition affects both hypothalamic and pituitary activity but the relative importance of direct and indirect effects of body condition on the sensitivity of these organs to steroid feedback, remains to be elucidated.

The study involved 120 crossbred ewes (sixty 1.5 years old animals and sixty 2.5 years old animals; initial liveweight 67.6 kg, condition score 3.7), that were mated in October. They were assigned to six treatments (two shearing treatments (shorn and unshorn) × two silage feed values (low and medium) and two extended grazed herbage allowances (1.0 and 1.8 kg dry matter (DM)/day)) designed to evaluate the effects of shearing at housing, grass silage feed value and extended-grazed herbage allowance on their performance and the performance of their progeny. Swards, which had silage harvested on 6 September, received fertiliser N (34 kg/ha) for extended (deferred) grazing between 19 December and lambing in mid-March. The herbage was allocated at DM allowances of 1.0 or 1.8 kg/ewe daily until 1 February. For the final 6 weeks of pregnancy, daily herbage DM allowances were 1.5, 1.6, 2.0, 2.0 and 2.0 kg for weeks 6, 5, 4, 3 and 2 to parturition, respectively. Two grass silages (low and medium feed value) were offered from housing on 19 December to lambing in mid-March. At housing, half the ewes were shorn whilst the remainder remained unshorn. Each ewe received 23.4 kg concentrate prior to lambing. For the extended-grazed herbage and the low and medium feed-value silages, DM concentrations were 132, 225 and 265 g/kg, and metabolisable energy (ME) concentrations were 10.0, 10.0 and 10.7 MJ/kg DM, respectively. Treatment did not alter (P > 0.05) litter size or number reared. Grass silage feed value did not significantly alter silage DM intake, or ewe and subsequent lamb performance. Increasing herbage allowance in mid-pregnancy decreased herbage utilisation (P < 0.05) and increased herbage intake (P < 0.05). Shearing increased silage intake (P < 0.05), lamb birth weight (P < 0.01) and tended to increase lamb weaning weight (P = 0.07). Relative to the housed shorn ewes, extended grazing did not alter (P > 0.05) ewe or subsequent lamb performance. It is concluded that shearing ewes at housing increased lamb birth weight due to increased silage intake probably associated with cold stress immediately post shearing and reduced heat stress in late pregnancy. Based on differences in lamb weight at weaning 0.8 kg of grass silage DM intake had the same feed value as a daily extended herbage DM allowance of 1.8 kg per ewe throughout the study. Neither silage feed value nor herbage allowance in mid-pregnancy affected lamb birth weight or subsequent growth rate.

The objective of this study was to estimate heritabilities for and genetic correlations among different pathogen-specific mastitis traits. The traits were unspecific mastitis, which is all mastitis treatments regardless of the causative pathogen as well as mastitis caused by Streptococcus dysgalactiae, Escherichia coli, coagulase-negative staphylococci (CNS), Staphylococcus aureus and Streptococcus uberis. Also groups of pathogens were investigated, Gram-negative v. Gram-positive and contagious v. environmental pathogens. Data from 168 158 Danish Holstein cows calving first time between 1998 and 2006 were used in the analyses. Variances and covariances were estimated using uni- and bivariate threshold models via Gibbs sampling. Posterior means of heritabilities of pathogen-specific mastitis were lower than the heritability of unspecific mastitis, ranging from 0.035 to 0.076 for S. aureus and S. uberis, respectively. The heritabilities of groups of pathogen ranged from 0.053 to 0.087. Genetic correlations among the pathogen-specific mastitis traits ranged from 0.45 to 0.77. These estimates tended to be lowest for bacteria eliciting very different immune responses, which can be considered as the overall pleiotropic effect of genes affecting resistance to a specific pathogen, and highest for bacteria sharing characteristics regarding immune response. The genetic correlations between the groups of pathogens were high, 0.73 and 0.83. Results showed that the pathogen-specific traits used in this study should be considered as different traits. Genetic evaluation for pathogen-specific mastitis resistance may be beneficial despite lower heritabilities than unspecific mastitis because a pathogen-specific mastitis trait is a direct measure of an udder infection, and because the cost of a mastitis case caused by different pathogens has been shown to differ greatly. Sampling bias may be present because there were not pathogen information on all mastitis treatments and because some farms do not record pathogen information. Therefore, improved recording of pathogen information and mastitis treatments in general is critical for a successful genetic evaluation of udder health. Also, economic values have to be specified for each pathogen-specific trait separately.

Fat growth and distribution were studied by jointing and complete tissue separation of carcasses from 277 young bull progeny of eight sire breeds and two dam breeds, serially slaughtered at 300 kg live weight, 12 and 15 months of age. Growth impetus for fat in each joint was established from the allometric equation (Y = aXb). Differential growth of fat in different joints resulted in marked differences in percentage of fat in various joints as fattening progressed. Growth coefficients, b, for fat in each joint were homogeneous among breed groups, indicating similar fat development patterns over the weight range studied. Growth impetus for fat was lowest in the distal limbs and in the proximal hind limb. Fat growth in the proximal fore limb was proportional to total fat. Along the dorsal line, low impetus was found in neck and rump regions, increasing to a high impetus in the mid-back region. Ventrally the fat of the flank showed the highest growth impetus of all regions with fat in the brisket and flat ribs also showing an increasing proportion with increases in total fat.

Small but significant differences among sire breeds were found for the amount of fat in each joint at a standard amount of total fat in the carcass. Differences found among sire breeds in fat distribution were not associated with differences in maturity type.

Rangelands provide the main forage resource for livestock in many parts of the world, but maintaining long-term productivity and providing sufficient income for the rancher remains a challenge. One key issue is to maintain the rangeland in conditions where the rancher has the greatest possibility to adapt his/her management choices to a highly fluctuating and uncertain environment. In this study, we address management robustness and adaptability, which increase the resilience of a rangeland. After reviewing how the concept of resilience evolved in parallel to modelling views on rangelands, we present a dynamic model of rangelands to which we applied the mathematical framework of viability theory to quantify the management adaptability of the system in a stochastic environment. This quantification is based on an index that combines the robustness of the system to rainfall variability and the ability of the rancher to adjust his/her management through time. We evaluated the adaptability for four possible scenarios combining two rainfall regimes (high or low) with two herding strategies (grazers only or mixed herd). Results show that pure grazing is viable only for high-rainfall regimes, and that the use of mixed-feeder herds increases the adaptability of the management. The management is the most adaptive with mixed herds and in rangelands composed of an intermediate density of trees and grasses. In such situations, grass provides high quantities of biomass and woody plants ensure robustness to droughts. Beyond the implications for management, our results illustrate the relevance of viability theory for addressing the issue of robustness and adaptability in non-equilibrium environments.