An experiment was conducted to examine the effect of method and level of concentrate feeding on milk production characteristics in dairy cows offered a grass silage-based diet. Twelve treatments were used with 24 Holstein/Friesian dairy cows in a four-period change-over design experiment. Treatments consisted of three methods of concentrate feeding (twice daily, four times daily or complete diet) and four levels of concentrate feeding (2, 4, 6 or 8 kg/day). Offering a complete diet significantly reduced silage substitution rate (0·28 kg silage dry matter (DM) per kg concentrate DM) compared with concentrates offered twice daily (0·50 kg silage DM per kg concentrate DM; P < 0·01). Method of concentrate feeding had no significant effect on milk yield or milk fat concentration (P > 0·05), although the response in milk protein concentration to increased concentrate food level was significantly greater with twice and four times daily concentrate feeding than with complete diet feeding (0·59, 0·56 and 0·44 g/kg per kg increase in concentrate food level; P < 0·05). Increasing concentrate inclusion level significantly reduced silage DM intake (P < 0·001) but significantly increased (P < 0·001) total DM intake. Milk yield and milk protein concentration were significantly increased (P < 0·001) and milk fat concentration significantly reduced (P < 0·02) with increasing concentrate inclusion level. Total ration apparent digestibility coefficients were unaffected (P > 0·05) by either method of feeding or concentrate inclusion level. However, modified acid-detergent fibre apparent digestibility decreased significantly with increasing concentrate inclusion (P < 0·01). Results suggested that offering complete diets, with concentrates comprising on average 0·33 of total DM intake, increased both silage and total DM intake although this was not reflected in either increased milk yield or improvements in milk composition.

This work aimed to study the response of the growing rabbit caecal ecosystem (bacterial community and caecal environmental parameters) after a switch from a control to a low-fibre diet (LFD). A group of 160 rabbits were fed ad libitum a control diet (ADF: 20.4%) from weaning (36 days). At 49 days of age (day 0), 75 rabbits were switched to a LFD group (ADF: 10.7%), whereas 85 others (control group) remained on the control diet, for 39 days. Caecal contents were regularly sampled throughout the trial (60 rabbits per group). The bacterial community structure was characterized using CE-SSCP (capillary electrophoresis single strand conformation polymorphism) and total bacteria were quantified using real-time PCR. Redox potential (Eh), pH, NH3-N, volatile fatty acid (VFA) were measured in the caecum to characterize environmental parameters. The reduction of fibre in the diet modified the CE-SSCP profiles (P < 0.001) but not the diversity index (5.6 ± 0.8, ns). The number of 16S rRNA gene copies of total bacteria decreased (P < 0.01) in LFD rabbits compared with controls. In LFD rabbits, the caecal environment was less acid (+0.2 units; P < 0.01), more reductive (−11 mV; P < 0.05) and drier (+3.4 g 100 per g; P < 0.001), with an increase in NH3-N (+77%; P < 0.001) and a decrease in total VFA concentration (−17%; P < 0.001). We found significant correlations between the bacterial community, the quantity of bacteria and the caecal traits of the caecal ecosystem. Indeed, in both groups, the caecal traits barely constrained the total inertia of the CE-SSCP profile set (less than 14%), whereas total bacteria were positively related to total VFA, acetic acid and butyric acid levels, and Eh, and negatively related to pH. All the microbial and environmental modifications had occurred by day 2 and remained stable thereafter. These results suggest that the bacterial community in the growing rabbit caecum is able to adapt quickly after a change to in the dietary fibre supply to reach a new steady-state equilibrium.

Sixteen pigs (eight entire males and eight females) were given individually two diets, control and control added 25% chopped chicory roots for 2 months before slaughter. Samples were taken from the contents in colon and rectum and subjected to GC-MS analysis for amount of odour impact compounds. The compounds 2-pentanone, ethylbutyrate, propylpropionate, butyric acid, ethyl-2-methylbutyrate, p-cresol, indole and skatole showed a significant difference between the two treatments. The esters, which have relatively pleasant, often fruity odours, increased in the chicory treatment, whereas the malodorous compounds, p-cresol, indole and skatole decreased in the chicory treatment. The measured amounts of compounds were corrected for their odour thresholds as different compounds can have widely different odour thresholds. Principal components analysis was then used to analyse the raw and corrected data results. p-Cresol was the most malodorous compound and together with skatole and indole count as the most malodorous compounds in the colon and rectum cotents. However, butyric acid also had some minor influence. Feeding chicory roots decreased significantly the concentrations of these malodorous compounds, especially if the lowest odour threshold values are used as correction factors.

The mean daily digestible organic matter intake (D) of each of 47 adult sheep during a grazing period of mean length 48 days was estimated by the chromium sesquioxide/faecal nitrogen technique. Mean live-weights (W) and mean daily weight gains (G) were also measured.

The regression of D on W and G, and the underlying or functional relationship between D, W and G were both estimated. From the underlying relationship, the preferred equation, the maintenance requirement of a 100 lb. sheep at pasture is estimated to be 1·02 lb. digestible organic matter daily. This value is 24% higher than the corresponding value for housed sheep obtained previously by us.

This result is compared with other estimates of the energy cost of grazing and it is concluded that further work is needed in order to define those circumstances which elevate the maintenance requirements of grazing animals.

Five measures of persistency of milk yield were compared by means of apparent heritabilities and repeatabilities using 598 first lactation records from the Danish progeny testing stations and 354 records of all parities from Red Danish cows at a state experimental farm. Unbiased estimates of heritabilities could not be obtained because of common environmental effects. Results indicate that measures of persistency giving equal weight to single milk records are superior to measures giving different weight to single records.

Correlations between persistency, expressed as the absolute decrease of yield, and maximum daily yield were —0·46 to —0·52 (phenotypic) and —0·22 (genetic). Correlations between persistency and 305-day yield were —0·06 to —0·10 (phenotypic) and 0·02 (genetic).Correlations between persistency, expressed as the decrease of yield relative to level of yield in early lactation, and maximum daily yield were —0·06 to —0·13 (phenotypic) and 0·17 to 0·42 (genetic). Correlations between the measure of persistency and 305-day yield were 0·12 to 0·45 (phenotypic) and 0·45 to 0·69 (genetic).

This study investigates the effects of two feeding systems and two dairy cow breeds on milk yield and composition, physical and sensorial properties of Camembert and Pont-l’Evêque cheeses. The experiment consisted of a 2 × 2 factorial arrangement of treatments. A low energy grass diet with only 15% of concentrate (LowGS) was compared with a high-energy maize silage diet with 30% concentrate (HighMS). Thirty-four Holstein (Ho) and 34 Normande (No) cows in early lactation were assigned to one of two feeding systems for a 6-week period. Cows on the LowGS feeding system had lower milk yield, fat and protein content. In both feeding systems, No cows had lower milk yields but higher milk protein contents than Ho cows. The LowGS feeding system altered milk fatty acid (FA) composition by reducing saturated FA. Breed had only a small impact on milk FA. Concerning milk coagulating properties, only the firmness was reduced by the LowGS feeding and the Ho breed. The effects of breed and feeding system on the protein content of cheeses were more marked in Camembert cheese than in Pont-l’Evêque cheese. However, the Camembert cheese from Ho-LowGS was, in fact, characterized especially by lower protein content. LowGS feeding system and No breed produced more yellow cheeses. Feeding systems had limited effects on the firmness of Camembert and Pont-l’Evêque cheeses measured by penetrometry. In sensory analysis, Ho breed and LowGS feeding produced a Camembert cheese with a more melting texture in the mouth due to the increase of spreadability index and of proteolysis. The type of cheese also had an influence: the effects were more important on Camembert cheese than on Pont-l’Evêque cheese. Only the Ho-LowGS treatment produced a very specific Camembert cheese different from the others. The feeding systems and breed of dairy cow have no determinant effect on PDO (protected designation of origin) Camembert and Pont-l’Evêque cheeses, especially regarding taste. In this kind of trial, despite the effects of feeding systems and breed on milk composition, the role of cheese ripening and microbiology appears to be of considerable importance.

A promising tool to improve daily gain in pigs is the missense mutation (Asp298Asn) in the melanocortin-4 receptor (MC4R) gene, especially in the Belgian pig industry where the slow-growing Piétrain breed is very frequently used as the sire breed. The MC4R is expressed in the appetite-regulating region of the brain where it regulates feed intake and energy balance. The mutation has been associated with differences in fatness, daily gain and feed intake. However, less information on the correlated effects on meat quality is available. In order to evaluate the influence of the MC4R mutation on carcass and meat quality parameters, a total of 1155 pigs of a four-way cross were slaughtered at an average live weight of 109 kg, and data about daily live-weight gain, carcass and meat quality were collected. Allelic frequencies were 0.69 for the G-allele (298Asp variant or well-conserved variant) and 0.31 for the A-allele (298Asn variant or the mutated variant). Barrows and gilts were almost equally distributed in this population with, respectively, 49.9% and 50.1%. Moreover, independent of this mutation, the relationship between average daily gain (ADG) and carcass on the one hand and meat quality traits on the other hand was evaluated in this population. A significant positive influence of the MC4R mutation on ADG (P < 0.001) was found, accompanied by a higher fat thickness (P < 0.05) and a lower carcass lean meat content (P < 0.01), whereas muscle thickness and carcass conformation traits were not affected. The effects on meat quality traits were not significant, except for a lower shear force (P = 0.054) and a higher intramuscular fat content (P = 0.052) in AA animals. In the longissimus, pH and pork quality meter (PQM) values were not influenced, and effects on drip loss and colour were not apparent. Residual correlation coefficients between ADG and carcass lean meat content on the one hand and meat quality traits on the other hand were generally very low (|r|>0.1). Higher ADG, higher carcass fat thickness and lower carcass lean meat content were correlated with slightly lower shear force values (|r|∼0.1, P < 0.05). In conclusion, in the studied population, the Asp298Asn mutation in the MC4R gene was associated with improved daily gain, higher carcass fatness and almost no effect on meat quality traits.

Up to the 18th century, the prevailing view of reproduction, or ‘generation’ as it was referred to, was that organisms develop from miniatures of themselves, termed preformation. The alternative theory, epigenesis, proposed that the structure of an animal emerges gradually from a relatively formless egg. The teachings of the Ancient Greeks who argued either that both sexes each contributed ‘semen’ to form the embryo, or held a more male-centred view that the female merely provided fertile ground for the male seed to grow, dominated thinking until the 17th century, when the combined work of numerous scholars led to the theory that all female organisms, including humans, produced eggs. The sequence of events leading to the commercial use of artificial insemination (AI) date back to the discovery of sperm in 1678, although it took almost 100 years to demonstrate that sperm were the agents of fertilisation and a further 100 years for the detailed events associated with fertilisation to be elucidated. The first successful AI, carried out in the dog, dates back to 1780 while it was not until the early to mid-1900s that practical methods for AI were described in Russia. Inspired by the Russian success, the first AI cooperative was established in Denmark in 1936 and later in the United States in 1938. The next major advances involved development of semen extenders, addition of antibiotics to semen, and the discovery in 1949 that glycerol protected sperm during cryopreservation. Almost four decades later, the flow cytometric separation of X- and Y-bearing sperm opened a new chapter in the application of AI for cattle breeding. As we look forward today, developments in imaging sperm and breakthroughs in gene editing and stem cell technology are opening up new possibilities to manipulate reproduction in a way never thought possible by the pioneers of the past. This review highlights some of the main milestones and individuals in the history of sperm biology and the development of technologies associated with AI in cattle.

This experiment was conducted to test two different protein sources as alternatives to the commonly used fish meal (FM) in the diet of the European eel (Anguilla anguilla). Six experimental diets were tested in three replicated lots of European eels. All diets contained the same protein and energy content (ca, 300 g crude protein per kg dry matter and 18·5 MJ/kg, respectively) but differed in the nature of the protein source: FM was the only protein source in the control diet and was fully or partially (0–5: 0–5) replaced by meat meal (MM) or sunflower meal (SFM) in four other diets; a sixth diet included SFM as the only protein source but was supplemented with several essential amino acids. Food intake, fish growth and several indices of diet and protein utilization were measured. MM clearly was the poorest protein source while SFM could replace, at least 0·5 of the FM with no significant reduction in performance. In addition, the European eel was able to utilize the supplement of essential amino acids. The full-SFM diet was improved significantly when supplemented and results were not statistically different from the control FM-based diet. Overall, a good correlation was found between the results of each diet and the respective essential amino acid index, calculated using as reference the essential amino acid requirements previously defined for another eel species, Anguilla japonica. This index could be used as a reliable measure for an a priori evaluation of alternative protein sources to be included in commercial foods for eels.

Water-soluble components of feedstuffs are mainly utilized during the early phase of microbial fermentation, which could be deemed an important determinant of gas production behavior in vitro. Many studies proposed that the fractional rate of degradation (FRD) estimated by fitting gas production curves to mathematical models might be used to characterize the early incubation for in vitro systems. In this study, the mathematical concept of FRD was developed on the basis of the Logistic-Exponential (LE) model, with initial gas volume being zero (LE0). The FRD of the LE0 model exhibits a continuous increase from initial (FRD0) toward final asymptotic value (FRDF) with longer incubation time. The relationships between the FRD and gas production at incubation times 2, 4, 6, 8, 12 and 24 h were compared for four models, in addition to LE0, Generalization of the Mitscherlich (GM), cth order Michaelis–Menten (MM) and Exponential with a discrete LAG (EXPLAG). A total of 94 in vitro gas curves from four subsets with a wide range of feedstuffs from different laboratories and incubation periods were used for model testing. Results indicated that compared with the GM, MM and EXPLAG models, the FRD of LE0 model consistently had stronger correlations with gas production across the four subsets, especially at incubation times 2, 4, 6, 8 and 12 h. Thus, the LE0 model was deemed to provide a better representation of the early fermentation rates. Furthermore, the FRD0 also exhibited strong correlations (P < 0.05) with gas production at early incubation times 2, 4, 6 and 8 h across all four subsets. In summary, the FRD of LE0 model provides an alternative to quantify the rate of early stage incubation, and its initial value could be an important starting parameter of rate.

Stemming from The Worldwide Donkey Breeds Project, an initiative aiming at connecting international researchers and entities working with the donkey species, molecularly tested pedigree analyses were carried out to study the genetic diversity, structure and historical evolution of the Andalusian donkey breed since the 1980s to infer a model to study the situation of international endangered donkey breeds under the remarkably frequent unknown genetical background status behind them. Demographic and genetic variability parameters were evaluated using ENDOG (v4.8). Pedigree completeness and generation length were quantified for the four gametic pathways. Despite mean inbreeding was low, highly inbred animals were present in the pedigree. Average coancestry, relatedness, and non-random mating degree trends were computed. The effective population size based on individual inbreeding rate was about half when based on individual coancestry rate. Nei’s distances and equivalent subpopulations number indicated differentiated farms in a highly structured population. Although genetic diversity loss since the founder generations could be considered small, intraherd breeding policies and the excessive contribution of few ancestors to the gene pool could lead to narrower pedigree bottlenecks. Long average generation intervals could be considered when reducing inbreeding. Wright’s fixation statistics indicated slight inbreeding between farms. Pedigree shallowness suggested applying new breeding strategies to reliably estimate descriptive parameters and control the negative effects of inbreeding, which could indeed, mean the key to preserve such valuable animal resources avoiding the extinction they potentially head towards, making the present model become an international referent when assessing endangered donkey populations.

This paper describes the relationship between protein-bound phenols in red clover, induced by different degrees of damaging before wilting and varying wilting duration, and in silo lipid metabolism. The ultimate effect of these changes on rumen biohydrogenation is the second focus of this paper. For this experiment, red clover, damaged to different degrees (not damaged (ND), crushing or frozen/thawing (FT)) before wilting (4 or 24 h) was ensiled. Different degrees of damaging and wilting duration lead to differences in polyphenol oxidase (PPO) activity, measured as increase in protein-bound phenols. Treatment effects on fatty acid (FA) content and composition, lipid fractions (free FAs, membrane lipids (ML) and neutral fraction) and lipolysis were further studied in the silage. In FT, red clover lipolysis was markedly lower in the first days after ensiling, but this largely disappeared after 60 days of ensiling, regardless of wilting duration. This suggests an inhibition of plant lipases in FT silages. After 60 days of ensiling no differences in lipid fractions could be found between any of the treatments and differences in lipolysis were caused by reduced FA proportions in ML of wilted FT red clover. Fresh, wilted (24 h) after damaging (ND or FT) and ensiled (4 or 60 days; wilted 24 h; ND or FT) red clover were also incubated in rumen fluid to study the biohydrogenation of C18:3n-3 and C18:2n-6 in vitro. Silages (both 60 days and to a lower degree 4 days) showed a lower biohydrogenation compared with fresh and wilted forages, regardless of damaging. This suggests that lipids in ensiled red clover were more protected, but this protection was not enhanced by a higher amount of protein-bound phenols in wilted FT compared with ND red clover. The reduction of rumen microbial biohydrogenation with duration of red clover ensiling seems in contrast to what is expected, namely a higher biohydrogenation when a higher amount of FFA is present. This merits further investigation in relation to strategies to activate PPO toward the embedding of lipids in phenol–protein complexes.

1. An experiment was conducted in which the effects on growth rate, food conversion efficiency, digestibility and rate of passage through the gut of diets containing 85% of differently processed barley, fed to growing pigs, were studied. Five different processing treatments were compared with the inclusion of the grain in the whole (unground) form (diet W). The processing treatments were: grinding through (1·56 mm), (4·68 mm) and (9·36 mm) screens (diets O, T and S respectively); cold rolling (diet R) and coarse crimping (diet C).

2. Differences in growth rate and food conversion efficiency between diets O, T, S and R were small and not significant with a slight overall superiority evidenced for diet R over the other three. Compared with these results those of diets C and W were inferior, significantly so for both diets in growth rate but for diet W only in food conversion efficiency. Diet C was superior to diet W in both of these parameters (significantly so for growth rate).

3. The overall digestibility of diet W was significantly poorer and the rate of passage through the gut faster than for any of the other diets. Diet O was retained in the gut significantly longer than any of the other diets and gave the highest coefficient of apparent digestibility for both the ether extract and crude fibre fractions of the diet.

This study quantified individual phenotypic variation in live weight and live-weight changes during the first three lactations and estimated the effects of age, lactation week and pregnancy on live weight. Data comprised weekly averaged live weight (calculated from daily observations) during 452 lactations of 239 Holstein-Friesian cows. Unadjusted mean live weights were 553 (s.d. 50), 611 (s.d. 55) and 654 (s.d. 57) kg during first, second and third parity, respectively. Estimated effect of growth during parity was 46, 52 and 23 kg for the first three parities. Mean maximum weight loss was 26, 22 and 22 kg for first, second and third parity and variation was large among individuals. Week of lactation when cows had their maximum weight loss ranged from 7 weeks in first lactation to 13 weeks in third lactation. Estimated maximum effect of pregnancy on live weight during the lactation varied from 27 to 59 kg. Phenotypic variance in live weight increased with parity. Repeatabilities of live-weight observations within parity were 0.85 . Across parities, high repeatabilities were found for calving weight and mean live weight but not for parameters associated with maximum weight loss. Correlations between weekly means and mean live weight during the whole of lactation were high. It was concluded that single live-weight observations of heifers are a good measurement of mean live weight during the first three panties.

The herd life of dairy cows was approximated by a single lifespan value based on the geometric distribution and accounting for the number of lactations each cow had completed or, if still in the herd, was expected to complete. For cows which had completed lactation n, but had not had time to complete lactation n + 1, the probability of survival from lactation n to complete lactation n + 1, from n + 1 to n + 2 etc. was incorporated, utilizing average population survival probabilities.

Formulae for the genetic variance in lifespan, its heritability and the genetic regression of breeding value on phenotype, the latter found to be independent of the amount of information included in the phenotype, are derived and checked by simulation.

From an analysis of 25227 dairy cows, each with the opportunity to complete five lactations, the heritability of lifespan was 0·06 and its genetic correlation with survival to complete three, four and five lactations ranged from 0·90 to 0·96, for both complete and incomplete survival information, showing that the lifespan trait appears to account adequately for missing observations. Genetic correlations between lifespan and first lactation yield traits were around 0·50, whilst the corresponding phenotypic correlations were approximately 0·13.

With the aim of testing the effects of food quality on meal patterns 127 213 visits by 22 lactating cows to 12 computerized feeders supplying two foods, high forage (HF) and high concentrate (HC) consisting of grass silage and concentrate were analysed. The foods were composed of the same ingredients but the proportion of concentrate dry matter (DM) in the food DM differed between HC (0·59) and HF (0·27). Each of the foods was offered ad libitum to 11 cows from the start of lactation until 156 (s.e. 9) days after calving. Mean daily fresh food intake (49·2 kg) was not affected by treatment. Mean daily intake of DM differed between HC (23·6 kg) and HF (17·8 kg). After estimating individual meal criteria, visits were grouped into meals. The mean daily number of meals was 6·6, the mean fresh food intake per meal was 7·6 kg and neither was affected by treatment. Cows consuming HF had longer meals (41·4 v. 31·3 min) but a lower feeding rate than cows consuming HC (233 v. 337 g of fresh food per min and 78 v. 156 g DM per min). Pre- and post-prandial correlation coefficients were sometimes statistically significant but always low (R2 from 0 to 0·05) and not affected by treatment. Food intake per hour of the feeding cycle (defined as the intake during a meal divided by length of the meal plus the duration of the preceding between-meal interval) showed a diurnal pattern in the shape of a sine-wave with low values of about 1·5 kg/h for cycles starting just after midnight and high values of more than 3·0 kg/h for cycles starting just after noon. Neither the mean, nor the amplitude, nor the shift of the sine-wave were affected by treatment. The data suggest that similar mechanisms are responsible for the short-term intake regulation of HC and HF. No evidence was found to suggest that the diurnal meal pattern of cows consuming HF deviated from that of cows consuming HC as a result of differences between foods in constraints related to their physical properties.

The voluntary intake of water by 24 groups of 3 to 6 Large White pigs (range of mean body weight: 21 to 73 kg) was measured during a total of 48 periods lasting 3 to 12 weeks each in a large calorimeter equipped as a pig pen. The calorimeter temperature was controlled between 7° and 33°C and the pigs were fed at levels ranging from 42 g feed/kg body weight per day to maximal intake. The mean water: feed ratios were between 2·1 and 2·7 at temperatures between 7° and 22°C, and between 2·8 and 5·0 at 30° and 33°C. The range of mean water consumption extended from 0·092 to 0·184 litre/kg body weight per day.

Multivariate restricted maximum likelihood analyses were carried out for a large data set comprising records for eye-muscle area, fat depth at the 12/13th rib and the rump P8 site, and percentage intramuscular fat, recorded via live ultrasound scanning of Australian Angus cattle. Records on heifers or steers were treated as separate traits from those on bulls. Reduced rank estimates of the genetic covariance matrix were obtained by restricted maximum likelihood, estimating the leading three, four, five, six, seven and all eight principal components and these were contrasted with estimates from pooled bivariate analyses.

Results from analyses fitting five or six genetic principal components agreed closely with estimates from bivariate and eight-variate analyses and literature results. Heritabilities and variances for ‘fatness’ traits measured on heifers or steers were higher than those recorded for bulls, and genetic correlations were less than unity for the same trait measured in different sexes. Eye-muscle area showed little association with the other traits.

Reduced rank estimation decreased computational requirements of multivariate analyses dramatically, in essence corresponding to those of an m-variate analysis for m principal components considered. Five or six principal components appeared to be necessary to model genetic covariances adequately. The first three of these components then explained about 97% of the genetic variation among the eight traits.

A simulation study showed that errors in reduced rank estimates of the genetic covariance matrix were small, once three or more principal components from analyses fitting five or more components were used in constructing the estimates. Similarly, accuracy of genetic evaluation for the eight traits using the first four components was only slightly less than that using all principal components.

Results suggest that reduced rank estimation and prediction is applicable for the eight scan traits considered. The leading three to four principal components sufficed to describe the bulk of genetic variation between animals. However, five or more principal components needed to be considered in estimating covariance matrices and the ‘loadings’ of the original traits to the principal components.

The effects of maturity of maize at harvest, level of inclusion and potential interactions on the performance, carcass composition, meat quality and potential concentrate-sparing effect when offered to finishing beef cattle were studied. Two maize silages were ensiled that had dry matter (DM) concentrations of 217 and 304 g/kg and starch concentrations of 55 and 258 g/kg DM, respectively. Grass silage was offered as the sole forage supplemented with either 4 or 8 kg concentrate/steer daily or in addition with one of the two maize silages at a ratio 0.5 : 0.5, on a DM basis, maize silage : grass silage supplemented with 4 kg concentrate daily. The two maize silages were also offered as the sole forage supplemented with 4 kg concentrate/steer daily. The forages were offered ad libitum. The six diets were offered to 72 steers (initial live weight 522 s.d. 23.5 kg) for 146 days. There were significant interactions (P < 0.05) between maize maturity and inclusion level for food intake, fibre digestibility and daily gain. For the grass silage supplemented with 4 or 8 kg concentrate, and the maize silages with DM concentrations of 217 and 304 g/kg offered as 0.5 or 1.0 of the forage component of the diet, total DM intakes were 8.3, 9.8, 8.9, 8.2, 9.2 and 9.8 kg DM/day (s.e. 0.27); live-weight gains were 0.74, 1.17, 0.86, 0.71, 0.88 and 1.03 kg/day (s.e. 0.057); and carcass gains were 0.48, 0.73, 0.56, 0.46, 0.56 and 0.63 kg/day (s.e. 0.037), respectively. Increasing the level of concentrate (offered with grass silage), maize maturity and level of maize inclusion reduced (P < 0.05) fat b* (yellowness). The potential daily concentrate-sparing effect, as determined by carcass gain, for the maize silages with DM concentrations of 217 and 304 g/kg offered as 0.5 and 1.0 of the forage component of the diet were 1.3, −0.3, 1.3 and 2.4 kg fresh weight, respectively. It is concluded that the response, in animal performance, including maize silage is dependent on the stage of maturity and level of inclusion in the diet. Maize silage with a DM of 304 g/kg offered ad libitum increased carcass gain by 31%, because of a combination of increased metabolizable energy (ME) intake and improved efficiency of utilization of ME, and produced carcasses with whiter fat.

An analysis has been made of the reproductive performance of a breeding flock of Clun Forest ewes in Northumberland. Data are based upon 941 breeding females and 75 males. The average lambing percentages were 43·9 115·4 and 137·7 for ewes aged 1, 2 and over 2 years. Total lamb mortality to 3 or 6 weeks of age was 23·7% for lambs from 1-year-old dams, 16·6% from 2-year-olds, and 12·9% from older ewes. Mortality for all ages of dams was 12·1 % for single lambs, 15·0% for twins and 34·0% for triplets. Birth weight was strongly associated with survival within all birth types and maternal ages.

Analyses of weights at birth, 21, 42 and 112 days showed that much of the observed variation in lamb weight was associated with age of dam and type of birth and rearing. Single lambs and those from mature dams were significantly the heaviest. The effect of age of dam on lamb weight decreased sharply from birth to weaning, whereas the type of birth and rearing was the major influence at 21 and 42 days, and was still important at 112 days.

The mean weights of all lambs adjusted by least squares analysis to the basis of male twins from 3-year-old dams were 9·2, 19·7, 30·6 and 62·7 Ib. at the four ages. Four- and 5-year-old ewes reared the heaviest lambs. Interactions between the effects studied were significant both within and between years and accounted for from 7 to 10% of the total variation. A single set of general correction factors at each age was shown, on average, to account for 80–90 % of the variation between subclasses within years and may have applicability to comparable flocks.