Within breeds and other captive populations, the risk of high inbreeding rates and loss of diversity can be high within (small) herds or subpopulations. When exchange of animals between different subpopulations is organised according to a rotational mating scheme, inbreeding rates can be restricted. Two such schemes, a breeding circle and a maximum avoidance of inbreeding scheme, are compared. In a breeding circle, flocks are organised in a circle where each flock serves as a donor flock for another flock, and the same donor–recipient combination is used in each breeding season. In the maximum inbreeding avoidance scheme, donor–recipient combinations change each year so that the use of the same combination is postponed as long as possible. Data from the Kempisch Heideschaap were used with computer simulations to determine the long-term effects of different breeding schemes. Without exchanging rams between flocks, high inbreeding rates (>1.5% per year) occurred. Both rotational mating schemes reduced inbreeding rates to on average 0.16% per year and variation across flocks in inbreeding rates, caused by differences in flock size, almost disappeared. Inbreeding rates with maximum inbreeding avoidance were more variable than with a breeding circle. Moreover, a breeding circle is easier to implement and operate. Breeding circles are thus efficient and flexible and can also be efficient for other captive populations, such as zoo populations of endangered wild species.

Concentrations of potentially toxic metals (PTMs) in the livers of pregnant, mature ewes and their 110 day foetuses, and in 6-month old lambs born to other ewes, were determined. The animals had been reared on pastures fertilized for 5 years with either sewage sludge (treated; T) or conventional inorganic fertilizer (control; C). The effects of treatment on patterns of accumulation of PTMs differed with stage of development and with individual PTM. In the liver of lambs, concentrations of Pb were elevated in T compared with C liver (P < 0·01), while Cu and Zn were lower (P < 0·001) in T than C liver. By contrast, in ewe liver, Cu concentrations were lower in T than C liver (P < 0·05), as in lambs, but there were no other treatment differences in PTM concentration. Ewe and lamb tissue data were not directly comparable because they were exposed to different diets but mean concentrations of Cd, Ni and Pb were approximately two- to four-fold higher in ewe than lamb liver while mean Cu concentrations were approximately five-fold lower, suggesting that more prolonged exposure to PTMs may have enhanced treatment differences in tissue PTM concentrations. Mean foetal PTM concentrations were not significantly affected by treatment. It is concluded that the repeated application of sludge to pasture is associated with altered, but not necessarily increased, rates of accumulation of PTMs in liver tissue, that rates of accumulation depend on the individual PTM measured and that they are probably influenced by duration and route of exposure and source of nutrient. Limited observations suggested that there was little effect of year, and associated variation in climatic conditions and herbage growth, on PTM accumulation.

Forty-eight spring-calving, Holstein-Friesian cows were continuously stocked on perennial ryegrass-white clover swards maintained at compressed sward heights of 4, 6 or 8 cm and offered 0 (U) or 4 (S) kg concentrates. Milk yields and composition, live weights and intakes (estimated by the n-alkane technique) were recorded for periods 24 May to 27 June (P1) and 28 June to 8 August 1992 (P2) with 4 cm swards not used in P2. Milk and component yields were significantly lower at 4 cm than at 6 or 8 cm in P1 and significantly higher when supplements were offered in both periods with no significant interaction. Herbage intakes were reduced more by supplementation at lower sward heights. Live weight was significantly lower on the 4 cm sward. Fat concentrations were unaffected by height and supplementation in P1 but significantly increased by supplementation in P2. These results suggest that maintaining a sward height of 6 cm offers advantages in terms of individual animal output and output per ha compared with grazing at greater or lower sward heights.

Two groups of 15 ewes in store body condition were either given a maintenance level of feeding or a twice-maintenance level (flushed) during the course of one oestrous cycle. Five ewes from each feeding level were slaughtered at 0, 18 or 48 h after the onset of the oestrus at the end of the treatment period and measurements were made of the luteinizing hormone content of their pituitary, the luteinizing hormone concentration in their blood plasma, their ovulation rates, and ovarian follicle numbers and sizes.

‘Flushed’ ewes had a significantly higher ovulation rate (260, s.e. 0·24 v. 1·80, s.e. 0·20; P <0·05), although there was no significant difference in either pituitary luteinizing hormone content or plasma luteinizing hormone concentrations at oestrus.

Analysis of the patterns of ovarian follicle distribution suggest that flushing ewes for one oestrous cycle might increase ovulation rate by preventing the late atresia of large follicles in the last 30 h before ovulation.

Most donkey and local horse breeds are vulnerable to extinction as mechanization of agriculture progress throughout the world. The present study analyzed the pedigree and herd records of the donkey Asinina de Miranda breed (RAM), identifying genealogical and human factors that may affect the breed genetic diversity in the future and suggesting suitable strategies to breed preservation, early on the conservation program. The breeding rate was very low, with a ratio of foaling/live animals of 0.23 (178/760). The estimated number of founders and ancestors contributing to the reference population was 128 and 121. The number of founder herds in the reference population was 64, with an effective number of founder herds for the reference population of 7.6. The mean age of herd owners was 65.50±0.884 years, with a negative association among the herd size and owner’s age (P<0.001). In contrast, the size of the herd and the ownership of a male were both positively associated (P<0.001) with the herd number of in-born foals. Both the owners’ age and the herd location (RAM home region v. dispersal region) were negatively associated with the foaling number (P<0.001). The main identified risk factors were: low breeding rates; low number of males and their unequal contribution to the genetic pool; unequal contribution of the herds to genetic pool; and advanced age of herd owners.

Twelve groups of five Israeli Friesian intact, individually fed, male calves, were slaughtered at different live weights. Commencing with 350 kg, the groups were slaughtered at intervals of 25 kg up to 625 kg live weight. Body and carcass composition data were obtained for each calf, and a feed conversion ratio was calculated.

Regression coefficients of age, feed conversion ratio and carcass data on empty body weight, and also the corresponding correlations, were calculated by the equations: y = b + αx for linear and y = bxα for nonlinear regressions.

Age increased at a rate very similar to that of empty body weight (α = 1·042). Increase in the amount of feed required to produce unit live weight was much slower (α = 0·045). With increasing empty body weight, dressing percentage and the percentage of kidney, channel and cod fat in the carcass increased moderately (α = 0·011 and 0·004 respectively), the percentage of the external organs decreased moderately (α = −0·010), and the percentage of bone in the carcass decreased very markedly (α = −0·277). The combined effect of these factors was to cause a marked increase in the percentage of saleable meat (α = 0·107) with increasing empty body weight.

Results indicate that it is possible to increase the marketing weight of Israeli Friesian male calves considerably without any detrimental effect on carcass composition or economy of production.

The aim of this study was to compare the environmental impact of the straw-flow system for fattening pigs with the slatted-floor system by measuring pollutant gas emissions such as ammonia (NH3), nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2), manure nitrogen (N) content and emissions of water vapour (H2O). Three successive batches of 32 pigs were fattened. For each batch, pigs were allotted to two groups raised in separated rooms fitted either with a concrete totally slatted-floor system (0.75 m2 per pig) or with a straw-flow system (0.79 m2 per pig). With this last system, pigs were kept on a sloped floor, straw being provided daily at the top of the pen. Throughout the fattening period, about 34.4 kg of straw were supplied per pig. The straw, mixed with dung, travelled down the slope by pig motion and went out of the pen to a scraped passage. The solid fraction was scraped every day, stored in a heap in the room and removed every month, 1 week before each period of gaseous emission measurement. The liquid fraction was automatically pumped from the scraped passage into a hermetic tank, which was emptied at the end of each fattening period. Rooms were ventilated mechanically in order to maintain a constant ambient temperature. Once a month, the emissions of NH3, N2O, CH4, CO2 and H2O were measured hourly for 6 consecutive days via infrared photoacoustic detection. Mean daily emissions per pig fattened on the slatted floor or on the sloped floor were, respectively, 4.98 and 13.31 g NH3, 0.67 and 0.68 g N2O, 15.2 and 8.88 g CH4, 548 g and 406 g CO2 equivalents, 1.61 and 1.77 kg CO2 and 2.33 and 2.95 kg H2O. Except for N2O emissions, all the differences were statistically significant (P < 0.001). From the slatted-floor system, the amount of slurry removed per fattening period was on average 256 kg per pig. From the straw-flow system, solid manure amounted on average to 209 kg per pig and liquid manure to 53 kg per pig. The total N-content of the manure was 2.23 kg N per pig with the straw-flow system (solid and liquid manure) v. 3.26 kg N per pig for slurry from the slatted-floor system. This reduction of 30% observed with the sloped floor was mainly explained by the higher level of NH3-N emissions.

An experiment was conducted to examine whether increased CLA in milk of dairy cows fed fresh pasture compared with alfalfa and corn silages was because of ruminal or endogenous synthesis. Eight Holsteins were fed a total mixed ration using alfalfa and corn silages as the forage source in confinement or grazed in a replicated crossover design. The proportion of total fatty acids as CLA (primarily c9, t11-18:2) in g/100 g was 0.44 v. 0.28 in ruminal digesta, 0.89 v. 0.53 in omasal digesta and 0.71 v. 1.06 in milk during confinement feeding and grazing, respectively. Blood plasma CLA was 0.54 v. 1.05 mg/l for the two treatments, respectively. The increased concentration of CLA in milk with grazing likely resulted from increased synthesis through desaturation of t11-18:1 in the mammary gland.

The present study was conducted to determine the optimum age of Holstein dairy calves for an effective inclusion of alfalfa hay (AH) in starter feed on performance, apparent digestibility and feeding behavior. A total of 40 Holstein dairy calves (20 female and 20 male) were used in a completely randomized design in which calves were randomly assigned to one of four different dietary treatments including control (CON) calves fed starter feed without any forage and three treatments consisting of the same starter feed plus 15% chopped AH fed when calves were at the 2nd (AH2), 4th (AH4) or 6th (AH6) week of age. Calves were individually housed and bedded with sand that was replaced every other day. Feed and water were available ad libitum throughout the experiment. Calves were fed milk at 10% of birth BW twice daily until d 57. The study concluded when calves were 73 days old. Starter intake was recorded daily and BW was measured weekly. Data were analyzed as a complete randomized design by MIXED procedures of SAS. Results demonstrate that calves receiving AH treatments numerically consumed more starter feed (0.62 v. 0.78, 0.71 and 0.65 kg/day for CON, AH2, AH4 and AH6, respectively) and had greater average daily gain (ADG) compared with CON (0.48 v. 0.57, 0.49 and 0.49 kg/day for CON, AH2, AH4 and AH6), although the significant difference was observed only between AH2 and CON. Among AH treatments, calves in AH2 had better performance than AH6 in several cases including starter intake, ADG. No detectable differences were observed, however, in apparent dry matter, organic matter or CP digestibility among treatments. Ruminal pH and NH3 concentrations, measured on weeks 4, 6, 8 and 10, were lower for calves fed CON compared with other treatments, with ammonia concentrations decreasing over time. Calves in the AH treatments spent more time eating and ruminating compared with CON. Calves fed CON, however, spent more time on laying down compared with other treatments. Overall, results from the present study illustrated that inclusion of alfalfa in starter feed for calves at 2 weeks of age may improve feed intake, ADG and stimulate rumination in young Holstein dairy calves. Results, however, should be viewed with caution as the number of calves per treatment was small and large calf-to-calf variation may have affected the results reported.

The activation of the hypothalamic–pituitary axis is critical for the initiation and maintenance of reproductive cycles in pigs and is influenced by a number of factors, such as nutrition, metabolism and gonadal steroids. Kisspeptin is a neuropeptide that is expressed in discrete regions of the porcine hypothalamus and is positioned to mediate the action of many of these factors. The expression of kisspeptin in the pig hypothalamus does not appear to be regulated by gonadal steroids in the same way as other species. It is unclear if kisspeptin is mediating nutritional or metabolic effects on gonadotropin secretion in pigs as it takes large deficits in feed intake or BW to affect hypothalamic expression of the KISS1 gene in the porcine hypothalamus. There appears to be little genetic diversity in kisspeptin or its receptor that is useful for improving reproduction in swine. Both peripheral and central injection of kisspeptin strongly stimulates the secretion of gonadotropin hormones, LH and FSH, in gilts. Similarly, synthetic analogues have been developed and showed potential promise as tools to manage reproductive cycles in gilts and sows. Review of the literature nonetheless reveals that research on kisspeptin and its function in controlling reproduction in pigs has lagged that of other livestock species.

An experiment was conducted to examine the response of three genotypes of beef cows to contrasting levels of nutrition supplied from grazed pasture. Twenty-two Hereford × Friesian (HF), 20 Aberdeen Angus × Friesian (AF) and 24 Welsh Black (WB) spring-calving beef cows with their Charolais-cross calves were used in 4 years consecutively. During the summer grazing period they grazed permanent pasture maintained at either 4 to 5 cm (short) or 7 to 8 cm (tall) sward surface height. Sward height treatment significantly (P < 0·001) affected cow and calf live-weight gain (0·498 v. 0·041 (s.e.d. 0·0405) kg/day and 1·12 v. 0·90 (s.e.d. 0·021) kg/day for cow and calf live-weight gain on the tall and short swards respectively). The live-weight gains of the HF and WB cows were similar, but the AF cows gained less weight on the tall sward and lost weight on the short sward. Calf live-weight gain reflected cow milk yield, with the calves from HF and AF cows having similar live weight gains (1·06 and 1·02 kg/day respectively) and those from WB cows having lower gains (0·95 kg/day; P < 0·001). The effect of sward height on calf live-weight gain was greatest in the WB-born calves because of the lower milk yield from WB cows. Body chemical composition changes of cows were predicted from live weight and body condition score, using prediction equations derived from separate groups of cows which were slaughtered at a range of body compositions for determination of chemical composition. Energy balances, calculated from changes in chemical composition, showed the AF cows to have the lowest energy balances with the WB cows the highest. Calculation of energetic efficiency and land use efficiency of weaned calf production taking account of annual food requirements indicated that the HF cows were most efficient, and the WB cows least efficient. The effect of increasing nutritional environment (as represented by sward height treatment) was such as to increase energetic efficiency for all genotypes, but land use efficiency was increased for HF and AF cows, and decreased for WB cows. These results indicate the factors such as size of cows, milk yield potential and pattern of nutrient partitioning can influence energetic land use efficiency of weaned calf production, and that important interactions between genotype and nutritional environment can occur in different measures of efficiency.

The effects of dietary protein (151 to 282 g crude protein per kg dry matter (DM)) and lysine (8·5 to 16·4 g/kg DM) on the carcass composition and energy metabolism of entire male pigs, given food close to appetite, was studied from 33 to 88 kg. Four replicates (three Landrace and one Duroc) of four littermates were used. Energy and nitrogen (N) balances were conducted at approximately 35 to 43, 58 to 65 and 78 to 85 kg and body composition was determined at slaughter. There was no effect of dietary treatment on the crude protein content of the empty body (EBW) but the DM (P < 0·001), fat (P < 0·001) and ash (P < 0·05) proportions and fat: protein ratio in EBW (P < 0·01) increased with decreasing dietary protein level. The mean maximum protein retention was 183 g/day. Retention of protein (P < 0·05) and proportion of protein energy in the gain (P < 0·01) decreased linearly and fat retention (P < 0·001) and energy content of the gain (P < 001) increased with decreasing dietary protein. The N retention values calculated from balance data were proportionately 0·21 higher at high protein intakes (509 g/day) and 0·056 higher at low protein intakes (329 g/day) than the values obtained by slaughter. Using the ideal protein system the value for the efficiency of utilization of apparently digested ideal protein for protein deposition (a2) fell linearly (P < 0·001), based on the slaughter data, as dietary protein content increased. Heat production, calculated from slaughter data, was proportionately 0·07 higher than that measured by indirect calorimetry and 0·17 higher than the computed value for heat production using the standard values of energy costs for maintenance and for protein and fat deposition.

Four animals from a group of eight Hereford × Friesian heifers weighing approximately 365 kg were implanted with 300 mg trenbolone acetate at the beginning of a 60-day trial period. Treated heifers grew more quickly (P<0·05) and converted food to liveweight gain more efficiently (P < 0·01) than untreated cdntrols. They had lower overall concentrations for serum albumin and plasma urea (P<0·01), the differences being maintained throughout the diurnal periods studied. No significant differences were recorded in the mean values for serum total protein, plasma glucose or free fatty acids. Similarly, the absence of significant differences in the mean values for serum growth hormone, insulin and prolactin suggested that these hormones did not mediate the response to trenbolone acetate. Implanted heifers had a significantly greater retention of nitrogen (P<0·01) which was mainly due to a reduction in the excretory products associated with total urinary nitrogen.

The most common housing system for reproduction rabbits, individual cage housing on a wire floor, is increasingly scrutinized because of its potential detrimental impact on animal welfare. We compared three types of housing: (1) individual cage housing on a wire floor (3952 cm2/doe, maximum roof height 63 cm, one 1000 cm2 plastic footrest/doe), (2) semi-group housing on a wire floor (5000 cm2/doe, roofless, one 1000 cm2 plastic footrest/doe) and (3) the same semi-group housing, but with a fully plastic slatted floor. In all housing systems, does had free access to an elevated platform. In the semi-group housing pens, four does were housed communally during 21 days of the reproduction cycle (to allow more space for locomotion and to increase opportunities for social contact), and individually during the other 21 days of the cycle (to minimize doe–doe and doe–kit aggression that peaks around kindling). In all, 24 Hycole does were included per system. The does entered the experiment at 203 days of age (after their first parity). The experiment consisted of four reproductive cycles, ending at 369 days of age. Pododermatitis was scored in cycles 1, 2 and 4. At the end of the 4th cycle the does were euthanized and X-rays were taken to assess spinal deformation. Tibia and femur length, width and cortical thickness were determined and bone strength was assessed using a shear test, as a measure of bone quality. Although severe pododermatitis was absent, the prevalence of plantar hyperkeratosis (hair loss and callus formation) at the end of the 4th cycle was much greater on the wire floor (65% and 68% for semi-group housing and individual cages, respectively) than on the plastic floor (5%, P<0.0001), even though the wire floors were equipped with a plastic footrest known to decrease hyperkeratosis. In contrast to our expectations, semi-group housing did not affect the prevalence of spinal deformations (P>0.10), but in line with our expectations bone quality was affected favourably by semi-group housing. The tibial cortex (and to a lesser extent the femoral cortex) was thicker in semi-group housing than in individual cages (1.45, 1.46 and 1.38 mm for semi-group housing on wire, semi-group housing on plastic and individual housing on wire, respectively, P=0.045). What this increase in cortical thickness means in terms of doe welfare requires further study, as it may reflect an increase in activity resulting either from increased space for locomotion, or from fleeing aggressive pen mates.

The objective of this review paper is to describe the development and application of a suite of more than 40 computerized dairy farm decision support tools contained at the University of Wisconsin-Madison (UW) Dairy Management website http://DairyMGT.info. These data-driven decision support tools are aimed to help dairy farmers improve their decision-making, environmental stewardship and economic performance. Dairy farm systems are highly dynamic in which changing market conditions and prices, evolving policies and environmental restrictions together with every time more variable climate conditions determine performance. Dairy farm systems are also highly integrated with heavily interrelated components such as the dairy herd, soils, crops, weather and management. Under these premises, it is critical to evaluate a dairy farm following a dynamic integrated system approach. For this approach, it is crucial to use meaningful data records, which are every time more available. These data records should be used within decision support tools for optimal decision-making and economic performance. Decision support tools in the UW-Dairy Management website (http://DairyMGT.info) had been developed using combination and adaptation of multiple methods together with empirical techniques always with the primary goal for these tools to be: (1) highly user-friendly, (2) using the latest software and computer technologies, (3) farm and user specific, (4) grounded on the best scientific information available, (5) remaining relevant throughout time and (6) providing fast, concrete and simple answers to complex farmers’ questions. DairyMGT.info is a translational innovative research website in various areas of dairy farm management that include nutrition, reproduction, calf and heifer management, replacement, price risk and environment. This paper discusses the development and application of 20 selected (http://DairyMGT.info) decision support tools.

1. The total rate of heat loss from individual pigs (20 to 40 kg body weight) was measured over 6-hr periods in a small heat sink calorimeter at 7°, 20° and 30°C, with feeding levels of 34, 39, 45 and 52 g/kg body weight per day.

2. Total heat loss at 7°C was significantly greater than at 20° or 30°C; there was no significant difference in heat loss between temperatures of 20° and 30°C.

3. Heat loss per m2 of body surface was independent of feeding level at 7°C. At 20°C, heat loss on the high feeding level was significantly greater than that on the low level, and at 30°C heat loss on both the low and medium feeding levels was significantly greater than that on the very low level.

Grape skin is a source of polyphenols with antioxidant and antimicrobial properties. Little information is available regarding its application in animal feeding. The present study investigated the effect of inclusion of fermented (FS) and unfermented (UFS) grape skin at two different doses (30 g/kg, FS30 and UFS30, and 60 g/kg, FS60 and UFS60) and 200 mg/kg vitamin E (α-tocopheryl acetate) in a corn–soybean diet on growth performance, ileal protein digestibility, ileal and excreta total extractable polyphenols content and digestibility, intestinal microbiota and thigh meat oxidation in broiler chickens. Growth performance was depressed in chickens fed UFS and FS diets. A reduction in ileal protein digestibility was also observed in birds fed UFS, being this effect more pronounced in those fed 60 g/kg. The dietary inclusion of grape skin increased both ileal and excreta polyphenols contents, being higher in birds fed UFS than in those fed FS. Excreta moisture content increased in birds fed UFS and FS diets. No effect of dietary inclusion of grape skin was observed on ileal counts of lactic-acid bacteria and Clostridium, but UFS inclusion in the diet reduced ileal count of Escherichia coli as compared with FS dietary inclusion. After 7 days of refrigerated storage, values of thiobarbituric acid reactive substances (TBARS) were lower in chicken meat when grape skin was added in the diet at 60 g/kg instead of 30 g/kg, and meat from birds fed 60 g/kg of grape skin reached TBARS values similar to those of birds supplemented with vitamin E. In conclusion, high doses of grape skin polyphenols depressed growth performance and protein digestibility, and increased excreta moisture content. Unfermented grape skin contained more polyphenols than FS, and its inclusion in the diet led to higher ileal and excreta polyphenols contents and to a lower ileal count of E. coli. Furthermore, the antioxidant potential of the polyphenols present in grape skin was observed after 7 days of meat storage, with the dose of 60 g/kg of grape skin being as effective as vitamin E supplementation in maintaining oxidative stability of meat.

A study was undertaken to ascertain the effect of pyridoxine in diets of varying protein to energy ratio (P: E) for Mediterranean gilthead seabream fry (Sparus aurata) with respect to protein utilization. Diets were formulated to provide three levels of added pyridoxine (0·5, 5·0 and 50·0 mg/kg), at two protein levels (320 or 470 g/kg) whilst maintaining a similar gross isocalorific profile at 20 MJ/kg. Feeding level was proportionately 0·02 of the fish body weight per day, resulting in the following effects after a 70-day feeding trial. Low P: E ratio diets (15 g/MJ) did not perform as well as high P: E diets (24 g/MJ), with respect to growth related indices. Higher inclusions of pyridoxine into diets of equal P: E ratios, caused elevations in food conversion efficiency, protein efficiency ratio and apparent net protein utilization. A marked improvement of growth rate concomitant with pyridoxine level only occurred in the high P: E diets. It was concluded that incremental additions of pyridoxine in the diet, increased the efficiency of protein utilization for all diets tested. However, the protein sparing effect oflipid was not achieved for the low protein diets indicating the relatively high requirement for protein in the growth of the juvenile seabream.

Three experiments were carried out to evaluate the effects of varying levels of mineral and iodine supplements when offered to ewes in late pregnancy on lamb serum immunoglobulin G (IgG) concentrations. In experiment 1, 44 individually housed ewes were allocated to one of four treatments (no. = 11) and offered a basal diet of grass silage ad libitum which was supplemented with 500 g/day of a concentrate (190 g/kg of crude protein (CP)), in addition to mineral/vitamin fortification at the rate of 0 g (C), 17.3 g (LM), 34.6 g (MM) or 52.0 g (HM) per day for the final 7 weeks of pregnancy. The mineral/vitamin supplement contained Ca, P, Na, Mg, Mn, Se, I, Co, Mn and vitamin E. The ewes were milked at 1 h, 10 h and 18 h post partum and measured quantities of colostrum, proportional to lamb birth weight, were fed back to the lambs via a stomach tube. Treatment had no effect on total colostrum yield or total IgG yield to 18 h post partum (P > 0.05). There was a linear decrease in serum IgG concentration and IgG absorption efficiency as mineral supplementation increased (P < 0.001). In experiment 2, which was carried out in conjunction with experiment 1, 44 ewes were allocated to four treatments (no. = 11) and offered the same basal silage/concentrate diet as in experiment 1, in addition to receiving one of the following supplements : (C) control, as in experiment 1; (HM), as in experiment 1; (−I), ewes offered the same mineral/vitamin supplement as HM but with iodine excluded; (I0), ewes offered a daily mineral supplement of iodine only at a level of 40 mg per ewe, equivalent to the iodine inclusion in the 52 g of minerals offered in HM. The iodine-supplemented progeny (HM and IO) had lower (P < 0.001) serum IgG concentrations and higher soil scores (P < 0.05) than the C and −I progeny. In experiment 3, the effects of varying levels of iodine supplementation when offered to ewes during the final 6 weeks of pregnancy on lamb serum IgG values were examined. Forty-eight individually housed ewes were allocated to one of four treatments (no. = 12) and offered grass silage ad libitum, which was supplemented initially with 500 g of a concentrate (140 g/kg of CP) from days 99 to 130 of gestation and then replaced with 700 g/day of a concentrate (180 g/kg of CP) from day 131 of gestation until lambing. In addition, the diet of each ewe was supplemented on a daily basis with iodine at the rate of 0 mg (C), 8.9 mg (LI), 17.7 mg (MI) or 26.6 mg (HI). There was a negative linear reduction in serum IgG concentration and IgG absorption efficiency as maternal dietary iodine supplementation increased (P < 0.001). We conclude that supplementation of the ewe's diet in late pregnancy with 17.3 g of a mineral supplement as formulated in the current experiment lowers the lamb's ability to absorb colostral IgG, and offering only the iodine component of this mineral supplement, at a level which approximates to about one third of currently quoted toxicity levels, will result in reduced serum IgG concentration in the lamb. These findings suggest the need to re-examine current toxicity values for iodine.

A 4-year interdisciplinary study was performed to compare two organically managed sheep production systems, using 118 ewes and 24 ha each. The systems differed in the ewes’ reproduction rhythm: one lambing per ewe per year (1L/1Y), with the aim of balancing feed self-sufficiency and lamb marketing periods v. three lambings over 2 years (3L/2Y), with the aim of maximising ewes’ productivity. The sustainability was evaluated through ewes’ reproductive performance, lamb growth rate, carcass characteristics and quality, animal health, forage and feed self-sufficiency, soil mineral balance and gross margin. General animal health was assessed by recording ewe and lamb mortality and putative cause of death. Nematode digestive-tract strongyles parasitism was studied using faecal egg counts and necropsies. Carcass quality was assessed by recording carcass weight, conformation and fatness, and colour and firmness of subcutaneous fat. Thirty-three percent of 3L/2Y ewes lambed twice a year against 4% of 1L/1Y. Mean ewe productivity was 161.3% and 151.0% in 3L/2Y and 1L/1Y, respectively, and it was more variable between years in 3L/2Y. Average concentrate feed consumption and the corresponding cost per ewe were higher in 3L/2Y than in 1L/1Y (156 v. 121 kg, and €49.5 v. €39.3, respectively). Finally, average gross margin was lower in 3L/2Y than in 1L/1Y (€59 v. €65 per ewe, respectively). Even in year 2002, when ewe productivity was highest in 3L/2Y (193%), gross margin was not different between systems (€90 v. €86 per ewe in 3L/2Y and 1L/1Y, respectively), because of higher concentrate costs in 3L/2Y. The 3L/2Y animals presented a lower health status, with a higher lamb mortality (P < 0.05) and a higher digestive-tract strongyles and coccidia parasitism level (P < 0.05). Lamb carcass conformation, fatness and fat colour were not different between systems, but carcass weight and subcutaneous dorsal fat firmness were lower in 3L/2Y lambs than in 1L/1Y lambs (P < 0.05 and < 0.001, respectively). Intensification in an organically managed sheep system, through an increased reproduction rhythm, thus did not lead to better economic results and proved riskier, more variable and more difficult to manage, and so less sustainable. The less intensive system (1L/1Y) was both highly efficient from the animal standpoint and highly feed self-sufficient. The technical and economic results of this system were better than those of organic private farms in the same area and matched those of non-organic farms.