Genetic parameters were estimated for purebred and crossbred lambs of a local breed using a single trait animal model. The traits recorded were: birth weight (BWT), weight at 30 days (WT30), weaning weight (WWT), average daily gain from 1 to 30 days (ADG1) and average daily gain from 30 to 90 days (ADG2). Five different animal models were fitted for each trait; all including additive direct genetic variance and various combinations of additive maternal and environmental maternal effects. The most appropriate model was chosen based on likelihood ratio tests. Additive maternal and permanent environmental effects were important (P < 0·05) for birth weight in purebred and crossbred lambs, when compared with a model containing only additive direct effects. Inclusion of maternal permanent environmental effects provided a better fit (P < 0·05) for weaning weight in purebred lambs than a model containing only additive direct effects. Estimates of heritability from the model containing additive direct, maternal effects and maternal permanent environmental effects, but not additive direct-maternal correlation, for combined purebred and crossbred lambs were 0·32 for BWT, 0·19 for WT30, 0·24 for WWT, 0·26 for ADG1 and 0·12 for ADG2. Estimates of additive maternal and maternal permanent environmental variances, respectively, as a proportion of phenotypic variance were 0·06 and 0·07 for BWT, 0·05 and 0·02 for WT30, 0·02 and 0·03 for WWT, 0·03 and 0·05 for ADG1 and 0·00 and 0·03 for ADG2. Estimates of direct-maternal correlation in subsequent analyses were significant and ranged from −0·16 to −0·95 for live weights and from −0·73 to −1·0 for daily gains. However, the very large negative correlations probably resulted from undefined non-genetic covariances as well as possible antagonistic genetic effects. These results indicate that it would be possible to improve growth traits in a local sheep breed through genetic selection.

The research was carried out at the animal experimental station of the National Agricultural Research Institute of the French West Indies (Guadeloupe) in 1999. Effects on intake and digestion by sheep of addition of Gliricidia leaves to a diet of 35-day-old Digitaria decumbens (pangola) hay, have been studied. In a first trial (a 4×4 Latin Square design), four rams were fed four diets: hay (G0); hay plus 1300 g of Gliricidia (G0·25), hay plus 2600 g of Gliricidia (G0·50), hay plus 3900 g of Gliricidia (G0·75). Total dry matter intake (DM), hay and Gliricidia intake, total tract and rumen digestibility of DM and its components, microbial and total nitrogen flows were estimated. In a second trial (a 2×2 Latin Square design), the same animals received hay (G0) or Gliricidia (G1·00) ad libitum to estimate the rumen turnover of pangola and Gliricidia fibrous particle. Neutral detergent fibre and crude protein content of the Digitaria decumbens hay and Gliricidia were 746 and 51, 458 and 198 g/kg dry matter respectively. Total dry matter intake (DM) varied from 42·7 to 76 g DM/kg LW0·75 from G0 to G0·75. The rate of substitution of pangola by Gliricidia (decrease of pangola intake for one unit Gliricidia consumed) was 233 g/kg. The digestibility of cell-wall linearly decreased with increasing level of Gliricidia in the diet. No digestive interaction was registered in the mixed diets. The total nitrogen and microbial nitrogen duodenal flows increased with the level of Gliricidia in the diet. The rumen turnover of fibrous particles of Gliricidia was double that of pangola. The incorporation of Gliricidia in diets increases their nutritive value by higher intake and intestinal nitrogen duodenal flows, but no positive digestive interaction was observed between pangola hay and Gliricidia leaves.

A study was carried out on six hill farms in Northern Ireland over 2 years (1996–1998) to investigate the effect of ewe and ram breed on ewe prolificacy, lamb viability and weaned lamb output. On each farm, groups of 40 Scottish Blackface ewes (mature weight of 53·8 kg) were mated to Scottish Blackface, Blue-Faced Leicester and Texel rams. Similarly, groups of 40 Wicklow Cheviot ewes (mature weight 63·7 kg) were mated to Cheviot, Suffolk and Texel rams. All ewe×ram breed combinations were present on each farm. Overall, ewe prolificacy was similar in Blackface and Cheviot ewes (1·52 and 1·55 (S.E. 0·026) lambs born/ewe lambed). However, there was a farm×ewe breed interaction (P < 0·001) indicating that, whilst prolificacy was similar in Blackface and Cheviot ewes on the majority of farms (4 out of 6), on one farm prolificacy was higher in Blackface and on another lower, compared with Cheviot ewes. There were no farm×breed interactions for any of the other main production traits. The proportion of ewes lambing without assistance was higher in Cheviot compared with Blackface ewes when crossed with Texel sires (P < 0·001). Cheviot ewes produced heavier Texel-sired lambs compared with Blackface ewes (4·76 versus 4·51 (S.E. 0·076) kg; P < 0·05). Mortality levels were similar in lambs produced from Blackface and Cheviot ewes. The weight of lamb weaned per ewe was higher in Cheviot compared with Blackface ewes (41·5 versus 38·8 (S.E. 1·01) kg/ewe lambed; P < 0·05). However, the weight of lamb weaned per kg of ewe metabolic weight did not differ significantly between the breeds.

With Blackface ewes, the proportion of ewes lambing without assistance was lower for Blue-Faced Leicester compared with Blackface sires (P < 0·001). In addition, the proportion of ewes lambing without assistance was lower (P < 0·001) for Texel compared with both Blackface and Blue-Faced Leicester-sired lambs. Lamb birth weights were higher in Blue-Faced Leicester (P < 0·05) and Texel (P < 0·001) compared with Blackface-sired lambs (4·38, 4·51 and 4·09 (S.E. 0·076) kg, respectively). Similarly, the weight of lamb weaned per ewe lambed was higher (P < 0·001) with Blue-Faced Leicester and Texel compared with Blackface sires (39·8, 38·8 and 33·8 (S.E. 1·01) kg, respectively). The carcass weight of the male lambs 3 weeks post-weaning was significantly higher (P < 0·001) in Blue-Faced Leicester and Texel compared with Blackface-sired lambs (12·5, 12·0 and 10·2 (S.E. 0·20) kg, respectively). Carcass conformation classification was higher in Texel compared with Blue-Faced Leicester and Blackface-sired lambs (P < 0·001). Fat classification was higher in Texel (P < 0·01) and Blue-Faced Leicester (P < 0·05) compared with Blackface-sired lambs. With Cheviot ewes, a greater number of ewes lambed unaided (P < 0·05) with Cheviot and Texel compared with Suffolk-sired lambs. The number of lambs born dead was higher (P < 0·01) with Suffolk compared with Cheviot and Texel-sired lambs (0·14, 0·08 and 0·07 (S.E. 0·016) lambs born dead/ewe lambed, respectively). Growth rates were higher in Suffolk compared with Cheviot-sired lambs (P < 0·05). Overall, Suffolk (P = 0·06) and Texel (P < 0·001) sires produced a greater weight of lamb at weaning compared with Cheviot sires (40·0, 41·5 and 36·9 (S.E. 1·01) kg, respectively). Carcass weight of lambs 3 weeks post-weaning was higher for Suffolk (P < 0·05) and Texel (P < 0·01) compared with Cheviot-sired male lambs. Carcass conformation classification was higher in Texel and Suffolk compared with Cheviot-sired (P < 0·001) lambs. Fat classification was also higher in Texel compared with Cheviot-sired lambs (P < 0·05). Carcass chemical composition was not significantly affected by lamb genotype.

This group, which is concerned with the applications of mathematics to agricultural science, was formed in 1970 and has since met at approximately yearly intervals in London for one-day meetings. The thirty-third meeting of the group, chaired by Professor P. K. Maini of the Mathematical Institute, University of Oxford, was held in the Kohn Centre at the Royal Society, 6 Carlton House Terrace, London on Friday, 6 April 2001 when the following papers were read.

In a storage experiment with dairy cow manure, the effects of dietary protein content and manure type on ammonia, nitrous oxide and methane volatilization as well as overall nitrogen (N) loss from manure were investigated. Early-lactating cows received rations with 175, 150 and 125 g crude protein/kg dry matter. Each ration was tested in four manure storage systems reflecting typical farm conditions. These either contained total excreta with high amounts of straw (deep litter manure) or no straw (slurry) or, proportionately, 0·9 of urine and 0·1 of faeces (urine-rich slurry) complemented by the residuals with a low amount of straw (farmyard manure). Manure samples were stored for 7 weeks under controlled conditions and trace gas emission was repeatedly measured. Reduction of N intake decreased daily N excretion and urine N proportion and, on average, led to 0·7-fold lower storage ammonia emission rates on average. Total storage N loss was simultaneously reduced with the extent depending on urine N proportion of the respective manures. A lower dietary protein content furthermore reduced nitrous oxide emission rates in most manure types but increased methane emission from urine-rich slurry; however, global warming potential (based on trace gas output) of all manures was similar with low and high dietary protein content. In deep litter manure, characterized by the highest C:N ratio, emission rates of total N, ammonia and methane were lowest, whereas nitrous oxide values were intermediate. Substantial emission of nitrous oxide occurred with farmyard manure which also had the highest methane values and, consequently, by far the highest global warming potential. C:N ratio of manure was shown to be suitable to predict total N loss from manure during storage in all manure types whereas urine N proportion and manure pH were only of use with liquid manures.

Progress in politics and science often happens by accident. The unforeseen impact of the foot and mouth epidemic may fall into this category. Both the Ministry of Agriculture and vets were over-stretched dealing with the crisis and so badger culling, which was to have resumed on 1 May 2001, was suspended for a year; even routine TB testing of cattle is on hold.

It seems probable that the Krebs/Bourne badger culling trial will be abandoned altogether. At least seven of the ten ‘triplet’ badger cull areas have been disrupted, particularly in Devon/Cornwall and Gloucestershire/Hereford. Some 600 of the 2900 badgers culled were in these two areas, perhaps 120 with TB, but only some 25 infectious. Since these were from some 400 km2, encompassing 450 farms, it is hard to see how the culls will have made the slightest impact on cattle TB.

In fact it is already apparent that each TB badger has cost some £35000, which merely confirms the 1986 findings of the Dunnet Review that badger culls are a waste of money because they do not work. Professor McInerney, as part of the review, noted that ending badger culling was purely a political decision. If Labour had won the 1992 election, contingency plans were in place to end culls, but, sadly, by 1997 ‘New’ Labour decided it was politically safer to go ahead with the Krebs cull. Enough data ought to be available from the trial to concoct ‘scientific’ reasons to grasp the nettle and take the inevitable and long overdue decision politically to end this sorry farce, once and for all.