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The objective was to determine the effect of feeding diets differing in fibre content and source on backfat skatole content and boar taint score of entire male pigs. Sixty entire male pigs (Pietrain×Seghers hybrid cross) were assigned to four dietary treatments and fed ad libitum, in two phases (grower and fattening), one of the following diets: control, one with 15% sugar beet pulp, one with 30% wheat bran and one with 15% soybean hulls. The diets were isocaloric and isonitrogeneous, but differed in crude fibre content and fibre source. Mean crude fibre contents were 5.2, 7.7, 6.2 and 9.9%, respectively. Animal performance, carcass quality, backfat skatole and indole contents and boar taint scores were not influenced by diet. However, the wheat bran diet group gave a numerically (P=0.219) higher backfat skatole content than the sugar beet pulp diet group (126±182 vs 37±54 ng/g fat; mean±S.D.). Under the experimental conditions, there was no higher risk for skatole formation or boar taint occurrence by feeding fibre-rich diets to entire male pigs, compared with a conventional diet.

Twenty four mature twin-bearing ewes in late pregnancy were used to compare the effects of feeding grass silage (GS), maize silage (MS) or a maize silage/ensiled super pressed pulp mixture (MS/ESPP), 60:40 on a DM basis, on voluntary feed intake, ewe weight and body score changes, lamb birth weight, colostrum yield and quality, and lamb growth rate to weaning. Each of the diets was supplemented with a barley/soya-bean concentrate (BS) containing 208 g crude protein kg −1 DM. The trial commenced on day 98 of pregnancy from whence the ewes were individually fed and their diet supplemented with BS at the rate of 213.5 g DM ewe−1 day−1 from days 98 to 125 of pregnancy and at 427 g DM day−1 from days 126 of pregnancy until parturition. The ewes were milked at 1, 10, and 18 h post lambing. Silage DM intakes (kg day−1) were higher on the MS/ESPP diet (P < 0.05) than on the GS or MS silage-based diets. From days 98 to 142 of pregnancy, mean ewe weight gains (kg) of 9.11, 11.37 and 13.12 (sem = 1.009) (P < 0.01), and body condition losses of 0.14, 0.34 and 0.02 (sem = 0.105) (P < 0.05) were recorded for GS, MS and MS/ESPP, respectively. Ewe body weight losses between day 98 and 24 h post lambing (kg) were 2.50, 2.44 and 1.44 (sem = 1.152) and litter birth weights (kg) of 9.84, 9.36 and 10.62 (sem = 0.434) (P < 0.05) were recorded for GS, MS and MS/ESPP, respectively. Colostrum yield (g) at 1 h of 605 ± 92.0, 526 ± 78.5 and 711 ± 74.8 and total colostrum yield (g) at 18 h of 1927 ± 163.3, 1690 ± 139.4, 2208 ± 132.7 (P < 0.05) were recorded for GS, MS and MS/ESPP, respectively. Overall, there were only minor differences in performance between grass and maize silages but when 40% of the maize silage was replaced with ESPP, both DM and total DM intakes were increased relative to the MS treatment; the ewes gained more weight and lost least body condition, total colostrum yield was higher, and the lambs had a higher growth rate up to weaning.

Eight digestibility trials, carried out with wethers, demonstrated that dried sugar beet pulp is a highly digestible energy source for ruminants. Using 95 as value figure, the mean starch equivalent content of the eight different lots amounted to 63.2 (73.3 in the dry matter) this corresponds with approximately 90% of the value of rolled barley. Beef production trials were carried out with 779 young bulls (322 baby-beef bulls and 457 store bulls) fed ad libitum with complete dry rations containing, respectively, 50, 60, 70 or 95% dried sugar beet pulp pellets. Straw and water were always available. Soybean oil meal was added to the first three rations, to increase the protein content, while in the last ration 0.85% urea was incorporated, or a liquid supplement containing 9.5% urea was available in a small tank with lick-wheel. From the fattening experiments it can be concluded that dried sugar beet pulp is a palatable feedstuff which can be used as sole energy source for finishing bulls. Dried sugar beet pulp supplemented with urea, minerals, micro-elements and vitamins resulted in high performances, high quality carcasses and an acceptable feed cost price. The use of a liquid supplement besides dried sugar beet pulp gave satisfactory results but further studies concerning palatability will be needed.

The objective of the present paper is to review the factors which can affect N flow and surplus both at farm and at cow level in order to point out areas with scope for future improvement. Special attention is given to management factors and feeding. Besides information from the literature the paper is based on meta-analyses of our own and published results. With regard to effects of production systems, mainly Danish surveys have been chosen as examples demonstrating the effects obtained under practical conditions. A positive correlation between stocking rate and N surplus per hectare at farm gate level is demonstrated, but there is also a considerable variation in N surplus per hectare at a given stocking rate. A number of factors influencing N surplus and loss have been identified, and their impact on N surplus and production efficiency has been estimated. N excretion per animal is an important factor for N turnover at farm level. Analysis of herd data indicates that feeding strategy, breed and milk yield, together with energy conversion and the protein content of the diet, are important factors explaining N excretion and N efficiency of cows. Reduction of N intake by optimal synchronisation of energy and protein supply over time, especially in pasture-based systems, is one way of reducing N excretion from cows. Furthermore, the ideal profile of absorbed amino acids should be identified, and models to estimate amino acid supply to the intestine should be further improved. The effect of reducing N excretion from cows has to be evaluated at farm level as manure is used as fertiliser for crop production. Overall, it seems possible to reduce the N surplus through better management and feeding without reducing production efficiency.

This paper investigates whether pasture allowance before and at lambing affects ewe behaviour, lamb behaviour and subsequent twin and triplet lamb performance to weaning. The trial was carried out at Massey University Keeble Farm in New Zealand. At pregnancy scanning, 186 first cycle-mated ewes were identified as carrying twins ( n = 96) or triplets ( n = 90). The ewes were randomly divided into four nutritional treatments (2, 4, 6 and 8 cm post-grazing sward heights). Each treatment was replicated ( n = 12 ewes in each replicate during pregnancy) on two separate blocks. The trial ewes remained on the four nutritional treatments during pregnancy and parturition. The mean lambing date was the 9 September 2002. Within 12 h of birth lambs were weighed, their sex recorded and identified to the ewe. Maternal and lamb behaviours were then recorded for a period of 5 min. Twin litter weight at birth was similar for ewes grazing 2-, 4- and 6-cm sward heights. Increasing pasture allowance from just 2 cm to 4 cm to ewes with triplet litters increased litter weight at birth by 2 kg, increased weight of lamb weaned by 8 kg and improved litter survival to tagging by 4%. Triplet lamb survival to tagging increased by 15% from the lowest pasture allowance to the highest (from 2 cm to 8 cm). Triplet litter survival was similar to twin litter survival at the highest pasture allowance (8 cm; 2000 kg DM/ha). Pasture allowance had a greater effect on lamb behaviour than ewe behaviour and triplets were more affected than twins. Feeding level did not affect Maternal Behaviour Score (MBS); however, MBS was related to a number of lamb behaviours. Ewes on higher pasture allowances were more likely to stay with their litter at the tagging site. Ewes with triplet litters on the 2-cm sward height were further from their litter 5 min after tagging and high-pitch bleated significantly more than ewes on higher swards. These ewes were less likely to make contact with their lamb after tagging. Triplets born on lower pasture allowances were less likely to stand, locate their dam's udder and follow their moving dam. Fewer triplet lambs bleated following tagging and this might be why fewer ewes made contact. Ewes with triplets grazing high pasture allowances in late pregnancy can achieve litter survival rates similar to those with twins. Ewes with triplets require higher pasture allowances to achieve similar production as ewes with twin litters.

The number of group-housed non-lactating sows is increasing rapidly in Europe as a consequence of changed legislation initiated by elevated public concern of animal welfare. Lower litter size and pregnancy rate in group compared to individually housed non-lactating sows have been observed in several on-farm experiments. The overall aim of this paper is to consider whether the variation in energy intake in a group of non-lactating sows can influence variation in litter size and pregnancy rate. A review of existing literature with main emphasis on publications after 1980 was carried out to clarify whether pregnancy rate and litter size may be influenced by energy intake. The studies reviewed indicate that low energy intake compared to high energy intake before mating may impair litter size in gilts and in sows that experienced severe weight loss during lactation. Furthermore, moderate energy intake compared to low energy intake in the first 3 days after mating may reduce litter size in the gilt but not in the sows. Both pregnancy rate and litter size might be influenced by very low energy intake in the first 4 weeks of pregnancy. Based upon studies indicating that low ranking sows may consume considerably less than high ranking sows (e.g., 50–80%) in group-housed systems, it is suggested that the variation in feed intake in a group of restricted fed pregnant female pigs may be large enough to influence pregnancy rate and litter size.

The objective of this review paper is to document extensive bedded indoor and outdoor pig production in the United States, which has expanded due to growing niche markets for natural and organic pork. Bedded hoop (tentlike) barns are used for finishing pigs and gestating sows. Seasonal outdoor farrowing and some indoor bedded farrowing systems coupled with group lactation are used also. Most natural pork markets require outdoor or bedded settings, no subtherapeutic antibiotics or growth promotants, no animal by-products in feed, and a family farm production setting. Hoop-fed pigs have more backfat, smaller loin area, and lower carcass yield compared with confinement-fed pigs. Hoop-fed pigs have fewer aberrant behaviors and handle easier than confinement pigs. Health is similar except for an increase in internal parasites in hoop-fed pigs. Pigs in hoops are in larger groups than in confinement. Biosecurity in hoops is more difficult due to incoming bedding and open access. Hoop-fed pig performance varies depending on thermal environment, which is closely related to season and climate. Bedded hoop barns with individual feeding stalls provide an acceptable environment for gestating sows. Overall, product quality differences are relatively minor compared with wide variations in rearing environment for extensively reared pigs.

In Europe, organic beef production is based on grazing in summer and feeding a minimum of 60% roughage during the whole year. Although these recommendations were intended to improve animal health and welfare, several factors may cause problems in organic beef production systems. This paper gives an overview of welfare, health and product quality in organic beef production, with emphasis on organic steer production based on dairy-breed bull calves. A short overview of different production systems, highlighting the effect on health and welfare, is also given. Feeding aspects are discussed. Farm studies have shown that organic steer production involves large amounts of roughage; only small quantities of cereals are used compared to conventional production of bulls and calves. Fattening of organic steers may result in metabolic disorders due to sudden changes in the feed ration when changing from high roughage to high cereal content. Various problems relating to the production system are discussed. Subjective monthly observations indicate a good level of general health and welfare in organic steer production systems. On pasture, parasitic infection is the primary factor affecting animal health and productivity of organic beef. Rearing of young calves and the utilization of marginal grazing areas requires further attention. The effect of castration on health and welfare, and the effect of castration age and method, are also discussed. Product quality of organic beef is affected by the production system, especially sex, grazing and exercise. Grazing and exercise, which are inevitable components of an organic beef production system, may affect the eating quality due to darker meat color, risk of off-flavor, yellow fat, and a higher content of unsaturated fatty acids, including conjugated linoleic acid (CLA). Nevertheless, the overall effect on sensory attributes may be of minor importance. For the future, feeding large amounts of roughage, combined with a high bioactive forage content, could be one way of improving the product quality of organic beef.

Concerning to environmental protection, the reduction of nitrogen (N) excretion in animal production is required. In this paper, a computer model to predict the N excretion in growing-finishing cattle was developed and verified using the N intake and N content in the empty body which was based on the simulating equation of crude protein content in empty body weight (EBW). Furthermore, a minimal threshold of the N excretion was simulated for growing-finishing cattle with certain EBW and predicted average daily gain (ADG). This model would be valid for growing-finishing cattle of different breed types, frame sizes and sexes through the utilisation of equivalent EBW. Results of two trials on Italian growing-finishing steers were used to evaluate the computer model developed. The results showed that the simulated N (SN) content in empty body did not differ significantly with the real data; the simulated N excretion (SNE) was generally close to the actual N value when ADG predicted by metabolisable protein availability was similar to the real one (simulated: actual N excretion ≥0.8 on average). The application of this computer model is rather simple because it is possible to use the N intake and the difference of EBW during a certain period to predict N excretion. For environmental protection, minimal N excretion threshold could be used to decide the maximum number of growing-finishing cattle for a certain area.

a ´´ SERIDA-CENSYRA-Somio, C/Camino de los Claveles 604, E-33203 Gijon, Asturias, Spain b ´ Abstract The aim of this paper is to assess the suitability of including calf survival traits in the breeding objective of beef cattle improvement programs. To do so, we analysed the genetic parameters affecting calf survival during the perinatal period (PS), between the perinatal period and weaning (LM) and at weaning (WS) using Asturiana de los Valles breed field data. Up to 36 125 calf survival records were used in the analysis. Heritabilities estimated for the direct effect ranged from 0.033 to 0.084 for PS, from 0.011 to 0.112 for LM and from 0.039 to 0.142 for WS. Our results suggest that LM is not affected by a maternal genetic component, whereas its effect is slight and similar in magnitude for both PS and WS. In general, the analysed traits are affected by a slight maternal permanent environmental effect ranging from 1 to 2%. PS and WS seem to be consistently determined by the same genes, presenting genetic correlations between the respective direct or maternal genetic effects of 0.95 and 1.0. Genetic correlation between the direct effects affecting PS and LM was 0.745. Current analyses show that WS has a higher genetic variability than would justify the inclusion of calf survival at weaning in the beef cattle breeding objective.  2003 Elsevier B.V. All rights reserved.

This paper focuses on the changes in production, herd health and veterinary treatments in Danish organic dairy herds during approximately eleven years based on historic data from herds converted to organic milk production before 1990 (old organic herds) compared to herds converted in 1995 and 1999-2000 and herds that are still conventional. Herd size, milk production, the shape of the lactation curve, somatic cell counts and veterinary treatments for mastitis, retained placenta and ketosis are compared over time and between herd groups. The old organic herds differed from the other three herd groups by having lower milk production per cow, lower somatic cell counts and fewer treatments of mastitis. Herds converted in 1995 and 1999-2000 were comparable to the conventional herds before conversion for all analyzed parameters. However, herd size was larger than both the older organic herds and the conventional herds after conversion. Production was about 2 kg energy corrected milk lower per cow per day than before conversion and compared to the conventional herds. In the herds converted in 1999-2000 little difference could be seen in relation to udder health after conversion when compared to conventional herds. The organic herds had fewer treatments for retained placenta and ketosis than the conventional herds. The shape of the lactation curves changed over the 11 year period with better persistency from day 60 to day 305 in all herd groups except for the old organic herds, which had the best persistency in 1990.

In this paper the genetic relationships between major reproductive traits in beef cattle (Calving Date, Calving Interval and Age at First Calving) and type traits have been estimated to evaluate the usefulness of type classification in predicting reproductive performance in beef cattle. We estimated favourable genetic correlations between Calving Interval and type traits ranging from −0.027 to −0.297. However, type traits and Calving Date appear to be genetically independent and the genetic relationships between Age at First Calving and type traits are, in general, non-favourable. Genetic correlations between type traits and Calving Date ranged from 0.0 to –0.125. Genetic correlations between Age at First Calving and Final Score, Body Depth and Tight Development were, respectively, 0.399, 0.445 and 0.447. Our results suggest that the possibility of using type classification to construct an index to improve reproductive performance is little. The more reliable possibility to build a possible selection index comprising type classification and reproductive performance would be based on Age at First Calving. Type classification at first calving could help to increase the information to select dams to stay on the farm in subsequent calvings on the basis of their expected performance.

An experiment is performed to contemporaneously compare young rabbits six generations apart in order to evaluate the correlated response to selection on growth traits in a line selected on litter size at weaning for 21 generations. The selection method was based on a BLUP procedure using a repeatability animal model. The contemporary comparison was possible because techniques of embryo cryopreservation and transfer were used in generation 15. The direct response to selection between both generations has been studied by Garcia and Baselga [Livest. Prod. Sci. 44 (2002) 45–53] and was 0.51±0.25 rabbits weaned/litter (0.085 per generation). In this paper, growth traits have been studied and the results show that non-significant differences between both generations were found, using as covariate total litter size at birth. Also, heritability, genetic correlations between growth traits and litter size at weaning, and genetic trends have been estimated using mixed model methodology with all the data of the selection process (12 651 parities and 93 085 growth records across 21 generations of selection). The genetic correlations were close to zero and the estimated genetic trend for weaning weight and post-weaning daily gain were positive and significant but small, less than 0.3% of the means per generation.

EU Council Directive 91/630/EEC specifies a banded system of increasing space allowance for finishing pigs, which imposes a degree of inflexibility on housing management. The study presented in this paper investigated whether there are measurable differences in welfare when pigs are kept at the minimum stocking densities described by the bands of the regulations (B), compared to those calculated using an equation (E) relating space allowance and live weight; Area (m2)=0.030×Live weight0.67 (kg). Furthermore, the study compared different floor types [fully slatted (F), solid without straw (N) or solid with straw bedding (S)] at these stocking densities. Eighteen groups of 12 pigs were allocated to this 2×3 factorial experiment, between 29 and 110 kg live weight. Data were collected on a range of welfare parameters. No effects of the space allowance treatments or interactive effects between space allowance and floor type were found. S pigs showed higher levels of manipulative behaviours than N pigs (47 vs. 57% of time spent active, N vs. S; P

The paper summarises the results of a study for sustainable development of beef cattle production on peat bog soil pasture in Hungary. On-farm research was carried out for five years to gain some basic data about herbage production from peat bog soil pastures and animal performance resulting from their use by beef cows herds of different genotypes. Monitoring and study was carried out in three farms with both native and seeded grasslands for suckler cows. Each of the herds was composed of Hungarian Simmental (HS), Hereford (HE) and HS×HE crossbred cows (F1 and R1 generations). Herds were kept outdoors all year round and cows mated in summer, the calves being weaned in autumn. Significant differences were observed in reproduction and weaning performances between HS and HE cows. Calving rate was 79.3% and 82.6%, survival rate to weaning 97.6% and 91.3%, and 205-days weaning weight 193.2kg and 173.6kg respectively. There were significant heterosis effects in the case of crossbred cows (F1, R1) in both calving rate (+9.7% and +5.7% respectively), and the survival rate of F1, R1 and R2 calves (+6.3%, +3.5%, +0.7% respectively). Annual herbage production differed significantly between years, farms and pasture types. The range in variation was from 2.82 to 3.42 tonnes/ha for dry matter, from 27.8 to 34.4 thousand MJ/ha for metabolisable energy and from 3.85 to 6.15 kg/ha for crude protein. Calculated from the average dry matter annual production yield and cows requirements, the annual carrying capacity of the pastures studied ranged from 55 cows/100ha for the large size HS to 66 cows/100ha for the smaller size HE. The highest calf crop (50.7 weaned calves and 9.6 tonnes total weaning weight) was obtained in the case of F1 cow herds while the lowest (42.6 and 8.23 respectively) in the case of HS. Herbage and hair samples analyses for macro- and micro-elements showed that Na, Cu, Zn and Se supplied by the herbage are insufficient with respect to cows needs. A mineral supplementation could be beneficial in order to sustain health and reproduction.

The aim of the present paper is to investigate the effect of energy supplies on growth characteristics in pigs when protein supplies are non-limiting. An experimental program was carried out at INRA between 1992 and 1994 and involved 60 pigs from three types fed at five energy levels. The effects of energy intake on protein deposition (PD) and lean gain on one hand and on lipid deposition (LD) and fat gain on the other hand were found to be very similar, which is logical with the fact that more than 55% of PD and 80% of LD are deposited in lean and fat tissues, respectively. Our results indicate that PD increases with energy supplies according to a linear–plateau relationship, which slope ( β p ) and maximum value are influenced by genotype, sex, and stage of growth. From our results and those of literature, β p is reported to vary between 2.9 and 6.1 g per MJ digestible energy (DE) intake over the 45–100 kg body weight (BW) range. Simultaneously, LD increases linearly with energy level but neither the genotype nor the sex influence significantly the slope of the relationship (14.5 g/MJ DE between 45–100 kg BW). Differences in growth response to energy intake between types of pigs result in an important variation in BW gain and its composition associated to energy intake. Therefore, characterisation of relationships between growth components and energy intake specific to each type of pig is necessary for modelling response to energy intake.

An experiment to evaluate the effects of selection for yearling growth rate (average daily gain from birth to yearling age) on the major components of beef herd profitability was started in 1974. This paper describes the design, population structure, selection applied and the realised direct response to selection. Two divergent selection lines (high line and low line) and an unselected control line were created in a closed Angus herd. Generation intervals after 17 years of selection were 3.2 yr, 3.3 yr and 3.3 yr for high, control and low lines, respectively, resulting in a corresponding 5.5, 5.0 and 5.1 generations of selection. The high effective population sizes of 67, 106 and 71 per generation for high, control and low selection lines, respectively, resulted in a low rate of inbreeding per generation for each selection line (0.74% for high line, 0.53% for control line and 0.88% for low line). Average selection differentials per year were 0.016 kg/day and −0.018 kg/day for the high and low selection lines, respectively, resulting in a corresponding direct selection response per year of 0.006 kg/day and −0.007 kg/day. Using animals recorded prior to 1964 as the base, the mean estimated breeding value (EBV) for yearling growth rate at the start of the experiment (1974) was calculated to be 0.015 kg/day. After 17 years (1991) of selection average yearling growth rate EBV for high line calves was 0.115 kg/day, compared to 0.030 kg/day for the control line and −0.060 kg/day for the low line calves. Realised heritabilities were 0.37 ± 0.09 for the high line and 0.38 ± 0.09 for the low line.

This paper presents possible practical management applications of dairy cows' body weight (BW) data. Daily BW and milk yield (MY) data of 80 primiparous and 128 multiparous cows were collected during complete lactations in a commercial dairy and analyzed in relation to health problems, nutrition and milking frequency (MF). The criteria for health problems were established on half of the total events, and checked on the other half. Approximately 50% of health problems were identified by BW changes up to 3 days prior to the MY drop that set off the health alarm. Physiological criteria for cows to be transferred from recommended post-partum (pp) total mixed ration (TMR) to a normal recommended TMR of higher or lower density, were quantified by changes in coefficients of a 10-days-running linear regression of 3-days-running average daily BW and MY data as dependent variables, and day pp as the independent variable. These criteria were set as rules that were incorporated into a fuzzy logic (FL) expert system (ES) which was applied to the second half of the data set. In all cases the transfer decision was within 2 days of the time calculated individually for each cow. A similar technique was used to define criteria to reduce high MF after calving in order to: (a) prevent metabolic stress, and (b) decrease MF after achieving sufficient pp stimulus for the carry-over effect. It is concluded that daily BW data are valuable as information to improve both diagnosis and management decision making.

The aim of this experiment was to compare non-carriers and heterozygous carriers of the dominant RN − allele (Rendement Napole) for carcass composition, muscle distribution and technological meat quality in pigs. Crossbred slaughter pigs ( n = 79), from Hampshire sires, heterozygous for the RN − allele, and Swedish Yorkshire X Swedish Landrace dams were used. The animals were classified into RN − genotype according to the estimated glycogen level at slaughter (glycolytic potential) in the longissimus dorsi muscle. Carriers of the RN − allele had higher daily gain, fewer days on test and produced carcasses with higher lean meat content, and a larger proportion of ham. The major ham muscles were larger in the RN − carriers than in the non-carriers. The proportions between the individual muscles were changed due to the RN − allele, with a greater content of glycolytic ham muscles ( M. semimembranosus et adductor, M. biceps femoris, M. gluteus ) and a smaller content of M. quadriceps femoris in RN − carriers. RN − carriers had lower values for ultimate pH, Napole yield (yield after curing and cooking), crude protein, and dry matter, and higher values for glycolytic potential, drip losses, filter paper wetness, internal reflectance and ash content. No effect of the RN − allele was found regarding lactate and surface reflectances.

The objective of this paper was to investigate the influence of environmental policies on dairy cattle breeding goals. Linear programming was used to model a dairy farm, including multiple restrictions on product output and production factor input. Management was optimized to maximize labour income. Effects of genetic improvement on labour income (economic values) were derived for dry-matter intake capacity, body weight and milk production traits (carrier, fat, and protein). Also effects of genetic improvement on nitrogen losses of the farm were computed. Basic economic values calculated were −0.18, 0.78, 13.81, −0.05 and 0 for carrier, fat, protein, body weight and dry-matter intake capacity, respectively. With more stringent environmental legislation, the economic value of fat increased (1.68) and the economic value of body weight decreased (−0.21), with constant economic values of carrier, protein and dry-matter intake capacity. Effects of genetic improvement on nitrogen losses of the farm varied considerably. Generally, a higher fat production per cow resulted in a reduction of nitrogen losses, and an increase in body weight increased nitrogen losses.

This paper presents data on fertility and litter size obtained with artificial insemination with frozen semen in five breeds of Norwegian sheep. The study is based on cervical inseminations reported by the technicians/veterinarians for the period 1984–1988. During this period 3000–3600 elite ewes were inseminated each year with semen from genetically superior rams. In addition, lambing data from sheep recording was used in this study. The non-return rate (NR%), defined as percent ewes not returned to service within minimum 20 days, was estimated to be about 60%. This variate was affected significantly by technician/veterinarian, flock-year, ram, age of ewe, number of inseminations per heat, date and time of insemination. The analysis indicates a reduction in litter size at birth of about 0.2–0.4 lambs when elite ewes were artificially inseminated rather than naturally mated. The optimal insemination time was found to be 15–20 hours from heat detection. It is also shown that technicians obtaining high NR% also obtain lower reductions in litter size from AI.

In this study profit equations for milk, veal and beef bull production were developed to obtain economic values for different traits. Veal and beef production were described in terms of fat and protein daily gain. For categorical traits, dystocia and carcass quality traits, economic values were derived using an underlying continuous scale. Parameters in the profit equations were chosen to reflect the Dutch situation for Black and White cows, but they can be changed to fit other breeds and production circumstances. The consequences of altering beef production characteristics on growth and mature weight in dairy cows are discussed in the paper but not included in the economic weights. Without product output restrictions, economic values for milk carrier, fat and protein yield were Dfl −0.082, 5.70 and 12.85 per kg, respectively. Under a multiple restriction of milk yield and fat content on herd level, economic weighhs were Dfl −0.328, 1.04 and 12.60 per kg, respectively. The economic weight of calf mortality was Dfl −3.83 per % and the marginal costs of dystocia were Dfl 59.75 per cow per unit on the underlying liability scale. The economic value for birth weight was Dfl 5.40 per kg for dairy farmers, Dfl −4.59 per kg for veal producers and Dfl −6.91 per kg for beef producers. For veal calf producers, economic weights were Dfl 0.45 for daily gain (g/day ), 25.67 for dressing percentage (%), −14.22 for mortality (%), 26.48 for fleshiness, 0.06 for fat covering and 37.44 for meat colour in veal calves. For beef bull producers, economic values were: Dfl 0.59 for daily gain, 37.35 for dressing percentage, −18.20 for mortality, 81.07 for fleshiness and 7.39 for fat covering. Sensitivity analysis of economic weights to changes in price and production circumstances showed that future economic values might change dependent on level of output and prices.

This paper reviews the biology of wool, mohair and cashmere growth and the options available to sheep and goat farmers to manipulate the quantity and characteristics of fibre produced to meet processors' requirements. The annual pattern of fibre growth in sheep and fibre producing goats is photodependent and regulated by hormone action. In sheep and Angora goats, fibre growth rate is greater in summer than winter with the amplitude varying between breeds. Cashmere-producing goats grow fibre between the longest and shortest day after which it is shed. The large diversity in fleece and fibre characteristics between genotypes of sheep and goats can be used to change characteristics by selection. Fibre characteristics of greatest importance to processors are all of medium to high heritability. Negative genetic correlations between some important characteristics limit overall genetic progress achievable through selection. The principal non-genetic factors affecting fleece and fibre characteristics in both sheep and goats are age, nutrition, physiological status, disease and shearing regime. Further work is required to gain a greater understanding of biological changes occurring within the follicle and fibre during growth to facilitate the production of fibre of specific characteristics through breeding or altering animal management.

This paper gives an overview of some important results about the crossing of Jersey (J) with Black and White cattle (BW) in East Germany. The utilization of the J as a crossing partner for BWs leads to heterosis effects. Given the production conditions of the early GDR, the percent heterosis effect for milk fat production was about 7.5%. In contrast to the BWs, the second generation of interse mating of Black and White dairy cattle of the GDR (=SMR) showed an increase in heritability, especially with regards to milk yield. At the same time, modified heritabilities, particularly for milk fat and milk protein content within Fl-crossing J × BW are demonstrated. Moreover, a very strong negative correlation could be observed between milk yield and milk protein content in the Jersey crossings, particularly in the SMRs.

This paper presents the characteristics and the results of an analysis of the Lacaune dairy sheep with an animal model. The analysis involved 1 003 071 lactations of parity 1 to 7, exhibited from 1978 to 1989 by 340 541 Lacaune dairy ewes. After including useful pedigrees, 492 149 females and 8231 males were evaluated for milk yield. Fat and protein yields and contents, partially recorded since 1986, were also analysed. 27 groups were defined for unknown parents only, according to the sex and birth year of their progeny. Results were consistent with those obtained with the present evaluation system (IF2). For males, the correlations between expected breeding values ranged from 0.92 to 0.98, according to the traits and the distribution of the daughters between flocks. The estimated genetic trend for milk yield was found rather insensitive to the heritability value and reached about 0.18 genetic standard deviation per year, i.e. about two thirds of the phenotypic trend and 2.2% of the production level. Some indication is given about the gain in efficiency due to the animal model.

This paper reviews the fate of nitrogen in the feed of lactating dairy cows and considers the consequences of the various transactions for urinary N excretion. A simple computer model was established and used to investigate the major factors influencing urinary N. In setting the model up it was clear that a number of areas of uncertainty about nitrogen transactions in microbes or host tissues remain. The basal animal and area efficiencies for a herd producing 5000 litres of milk per cow per annum are 0.68 g milk N per g urinary N and 97.7 kg urinary N per hectare per annum. Feeding concentrates at 0.3 kg per litre of milk to obtain yields of 6700 litres per cow per annum increased these to 0.74 g and 191.0 kg respectively. Two major areas of uncertainty remain, the efficiency of capture of rumen degraded N by rumen microbes and the efficiency of utilisation of amino acids by host tissues. Simulations of the possible ranges in these variables illustrate the potential effects on nitrogen waste and the dietary crude protein required to support a given level of production. A major practical problem is that whilst it is very difficult to assess these variables under experimental conditions it is impossible to identify them at the farm level. This can lead to incorrect feeding decisions which merely exacerbate the problem. Given the simple assumptions of this model, the strategy that results in the lowest return of urinary N per forage hectare is an extensive system of production, particularly if this can be achieved using animals which have a high efficiency of transfer of amino acids into milk protein. Nevertheless, there is an urgent need to provide more consistent predictive relationships, and/or diagnostic tests for farm-use, in order to advance models and reduce urinary N excretion.

This paper reports estimates of genetic parameters for testicular diameter (TDM) from a random-breeding Merino flock maintained at Trangie, N.S.W. Over a period of 4 years, TDM was measured, generally monthly, on 800 rams from four Merino strains and 14 lines within these strains between weaning (4 or 5 months) and 12 months of age. In 2 of the 4 years TDM was again measured at age 19 months. The between-year source of variation was a highly significant component for all measures of TDM except at 4 and 19 months of age. Differences between strains were significant at some ages with changes of ranking occurring was rams approached 12 months of age. Lambs born as twins and triplets had significantly smaller testes up to 9 months of age while date of birth (6–7 week lambing period) had a significant effect up to and including 19 months of age. Rams born later had smaller testes. Paternal half-sib estimates of heritability of TDM between 6 and 12 months of age were all high, ranging between 0.49 ± 0.14 and 0.69 ± 0.14. AT 4, 5 and 19 months of age lower estimates were obtained (0.45 ± 0.19, 0.28 ± 0.13 and 0.22 ± 0.17, respectively). Genetic correlations between these monthly measures of TDM were generally high (> 0.75) except for those involving TDM at 4 months of age. Although the genetic relationship between weaning liveweight and TDM at 5 months of age was high (0.84 ± 0.18), weaning liveweight was lowly correlated with TDM at other ages (0.11–0.26). Correlations between 12-month liveweight and TDM at other ages were higher (0.51–0.74). AT 12 months of age liveweight and TDM were also highly correlated ( 0.80 ± 0.15).

Results of a farm-level analysis of selective measures for enhancing milk yield are discussed in this paper, using the example of bovine somatotropin (bST) which seems to be very appropriate for selective use because of its short-term applicability. Under the conditions of a milk quota system in particular, selective measures for influencing milk yield are of great importance. In the case of bST positive income effects are expected from treating cows with lower yields or cows with a high nutrient-intake capacity. Furthermore, seasonal milk price and fodder cost fluctuations are good reasons for influencing milk yield at certain periods. Finally, the application of bST only in certain parts of the lactation period is evaluated and the economic effect of using bST as an alternative for exact fulfilment of the milk quota on a yearly basis has been estimated. In summary it can be stated that positive income effects up to about 200 DM per cow per year can be expected depending on the application strategy of bST and excluding the costs for bST compound and treatment.

The characteristics of the genetic improvement of milking ewes are discussed, taking into account the obvious fact that they are both dairy animals and sheep. Two particular aspects of selection schemes are given: 1. (1) the need to rationalize and simplify milk recording with a view to minimizing its cost in relation to the commercial value of the product per head. 2. (2) the concurrent use of A.I. and natural mating. This paper deals mainly with the situation in France (Lacaune breed). Several selection tools are used: simplified recording in large mechanized flocks (AC recording and B type recording), “Centres d'Elevage de Jeunes Mâles”, artificial insemination for good distribution of the daughters of selected rams between the flocks. Genetic progress is mainly realized in the selection flocks by artificial insemination with improved males, and outside the selection flocks with the sons of the improved males which are used in natural mating.

The main feeding factors leading to optimum milk production in dairy goats are studied in this paper. Because of its high milk yield, the goat consumes large quantities of dry matter. Accordingly, the intake of energy seems to be the most important dietary factor influencing milk production. The amount of concentrates offered must be determined according to the type and the quality of forages. For obtaining maximum production the energy density of the diet must approximate 0.80 F.U./kg D.M. The annual feeding programme of the dairy goat must be adapted to its behaviour and must take into account its physiological status. Before and after parturition, feeding of good quality forages favourably affects the onset of lactation. The supply of concentrates before parturition should not exceed about 8 g D.M./kg L.W. After parturition, the increase in the concentrate intake of the goats should not be too rapid. In the middle of lactation and especially at the end of lactation, maintenance of milk production at a high level requires a slightly higher supply of concentrates than that necessary to meet the requirements for energy.

As a follow-up to earlier review papers, the available data on Finnsheep in different countries all over the world have been brought together. Apart from published material, other sources have been utilized, including answers to a questionnaire circulated in January 1976. Data on measured traits are summarized, and comparisons have been made between certain traits in Finland and abroad. The following main traits are reviewed: Fertility. Early sexual maturity is typical of the breed. Both ewe and ram lambs can be used for breeding at 6–8 months of age. Conception rate is 94–96% for ewe lambs and 95–98% for adult ewes. Litter size for 1-year-old, 2-year-old and adult ewes is about 1.8, 2.4 and 2.7, respectively. Lamb mortality varies from 7 to 40 %, depending on litter size. The majority of the ewes can conceive out of season. Oestrus lasts 2–2.5 days, and fertile oestruses occur during lactation. Ovulation rate is high. Rams show high libido, large testes and good fertility. High gonadal activity is common to both sexes of the breed. Mothering ability. Assistance at lambing is needed in 10–12% of cases. The average score for mothering ability in the scale from 1 to 4 was 2.65, but it varied greatly. The average score for milk production was 2.44 and the average daily milk yield 1.81 kg. Health. The average score for health was 2.38. In half of the places there were problems with pneumonia. Other health problems were specific for different places. Growth and carcass. The average birth weight is about 2.4 kg, but varies with litter size. Mean 150-day weight in Finland is 30 kg and daily gain ca. 180 g. The gain during the first 6 weeks depends on litter size. Litter weight at 150 days was 71 kg, but litters of 4–5 lambs were thrice as heavy as singles. Carcass yield of lambs is competitive with other breeds, but carcass quality 5–10% poorer. Fat is located mainly in body cavities, not subcutaneously. Wool. Fleece weights are inferior to most other breeds, being about 2 kg as greasy and 1.5 kg as clean. The wool is rather fine, 25–28 μm, white, semilustrous, soft and silky. Medullation is rare.

The working group conducted a seminar in Wageningen, The Netherlands, in April 1987. The objectives of the seminar were: 1. (1) a review and an exchange of results and experiments about performance testing of bulls in dairy and dual-purpose breeds; 2. (2) recommendations for testing procedures and further research needs. The comparison of performance test results with male progeny under different environments showed a clear positive relationship. It was concluded that performance tests should be comparable with the prevailing conditions the progeny have to fulfil, especially with regard to test period length and feeding intensity. Preliminary results from Denmark and The Netherlands about the relationship between performance test results and female progeny for feed efficiency indicated a slight positive relationship. Metabolic and immunological parameters (in connection with a challenge) of young sires may provide indications to metabolic stability in production and diseases. The estimation of breeding values for beef were discussed. The economic aspects of beef production in dairy and dual-purpose breeds were discussed under the EEC-situation with milk quotas. The studies presented showed that performance testing of young bulls is a useful approach to improve the efficiency of production. The papers of the seminar are available as E.A.A.P.-publication No. 34 (ISBN: 90-220-0924-6).

The first part of this paper reviews the Spanish literature dealing with the possibility of increased lambing frequency in Spanish flocks. Seasonal anoestrus occurs in all the Spanish breeds considered, although even in the most unfavourable month some sexual activity is observed, such as in Aragonesa flocks, where it reaches up to 80% in some years. The percentage of cyclical ewes in spring is favourably influenced by good feeding levels and by the introduction of males previously removed from the flock for a few months. In the second part we deal with the results obtained in several commercial farms in Aragon differing in mating management. No hormone treatments are used in these farms. In the farms where orderly and short matings are practised more lambings (1.39 vs. 1.29) and more lambs/ewe/year (1.76 vs. 1.40) are obtained than in those with continuous or nearly continuous mating periods. They can also choose the most favourable dates to obtain their lambs with regard to sale prices and ewe supplementary feed costs. In these conditions, Romanov × Aragonesa ewes give 40% more lambs/ewe than Aragonesa ewes without decreasing the number of lambings per year.

This paper deals with a part of the project on testing of 10 Friesian strains in Poland, organized with international co-operation. From large F1 populations tested in the field, 400 pregnant heifers (40 per strain) were chosen randomly and divided between two experimental farms, where they were kept under intensive and controlled feeding. Milk production and conformation characteristics were studied. The average first lactation milk yield was 4970 kg, with 3.97% butter-fat and 3.54% protein. The range of difference between the strain means for milk yield was about 1000 kg. The strains of Holstein-Friesian type (U.S.A., Canada and Israel) were best for milk yield, while the highest compositional quality tended to be in the strains from Dutch and New Zealand sires. Holstein-Friesian type strains were generally heavier and larger.

The results of main and short papers on the productivity of crosses between domestic and prolific breeds presented in Zurich in 1976 have been summarized according to the important reproduction and production traits. Fertility, prolificacy, mortality rate, litter size born and weaned, ovulation rate, accelerated and out-of-season lambing, milk production, growth and carcass traits were analysed. More attention has been paid to the reproduction traits, because of their importance in crossbreeding with prolific breeds. For all analysed traits the amount of heterosis has been estimated from various information sources: midparent value, F 1 , F 2 , B 1 (backcrosses), one of the parent breeds. The use of prolific breeds mostly leads to an improvement in the reproductive characters. The breed differences are decisive for all traits. The reproduction traits generally show higher heterosis effects than the production traits, but this statement cannot be held as a rule. For international comparisons in future the traits must be standardized.

A new and more effective piece of equipment for grading of pig carcasses (the KSA-meter), which automatically registers lean- and fat thicknesses on the warm carcass, has been constructed. The paper describes two investigations, which were carried out to examine the estimation of the lean content of the carcass from different measurements of fat and muscle depths, using this equipment. The results showed that it is possible to explain 65–75% of the variation in percentage lean in the carcass on the basis of three fat measurements and one measurement of muscle depth (RSD = 2.00−1.80). Body length did not improve the precision of estimating carcass lean percentage. The KSA-meter is now used in all factories in Denmark, and carcasses are paid according to estimated lean percentage, i.e., according to the real carcass value.

In this paper information has been summarized on natural factors affecting sexual development in the ewe. Considerable differences exist both between and within breeds of sheep in the age and body weight at puberty. Genetic as well as environmental factors, and the interaction between these, clearly affect sexual development. Of the environmental factors, the plane of nutrition during rearing and the time of birth appear to be of the greatest importance. Generally, faster growth is associated with enhanced reproductive performance in ewe lambs, i.e. earlier attainment of puberty, more intense oestrous activity and higher conception and lambing rates when mated. However, compared with mature ewes, the young females normally express lower reproductive efficiency. The potential contribution of the ewe lamb should be considered in relation to methods of improving the lifetime productivity of the ewe.

The objective of the present review was to consider the dietary factors involved in the adjustment of voluntary feed or energy intake in the growing pig. Energy concentration was the primary factor to be taken into account, in relation to growth potential and lean-tissue gain as affected by age, sex and genotype, as well as climatic environment. The effect of protein level and amino acid balance on voluntary feed intake is reviewed in the second part of the paper, by considering the compensatory increase in feed consumption following a moderate deficiency in the limiting amino acid or total protein, and the performance benefit to be expected from correcting amino-acid excesses in common diets. Finally, the separate regulations of energy and protein intakes are analyzed through self-selection of two dietary portions with different protein-energy ratios. The results obtained are further evidence that protein intake is separately regulated from energy intake and that both controlling mechanisms interact in determining overall feed intake.

The recent results of research carried out on housing and climatic conditions for early weaned piglets are reviewed in the present paper. Piglets weaned at 3–4 weeks of age are, in most cases, raised on a totally wired floor in weaning houses. The optimum area per animal and the number of piglets per pen depend on their age and weight at entry and leaving of the weaning house, respectively. The “all-in-all-out” management system is shown to improve the growth performance of piglets. The effects of some physical components of the thermal environment (air temperature, wind speed and relative humidity) on the growth, energy and nitrogen metabolism of the piglet were analysed. An interaction between the air temperature and the feeding level, on the one hand, and the air temperature and the management system (type of floor, piglets raised individually or in groups) on the other, was found. However, no definite conclusions can be drawn about the optimum environmental conditions for early weaned piglets.

In this first paper of a series, Dutch central test results are examined for genotype × environment interaction (G × E) and the data are further used to estimate genetic correlations between the various evaluations of growth and carcass quality, as used in the distinct environments of the breeding programme. G × E in pig breeding programmes is outlined as genotypes expressing different phenotypes in the distinct levels of the breeding programme or even in different environments within a level (e.g. herds). In most studies on G × E, the expectation of genetic correlation between similar traits measured in different environments has been taken to be one. Estimated correlations between similar traits measured on central tested pigs in this study indicate however, that expectations should be smaller, especially for carcass characteristics. Genetic correlations of carcass backfat thickness (CB) with ultrasonic backfat thickness (UB), normally used in on-farm tests, were 0.61 and 0.57 for Dutch Landrace (NL) and Dutch Yorkshire (GY), respectively. Correlations of UB with backfat class, as used in commercial fattening, were 0.25 and 0.42. Genetic correlations of ham + loin % with type class were 0.60 and 0.94. In future analyses of G × E these differences in genetic background of the traits should be taken into account. Genotype × batch and genotype × sex interactions were investigated for daily gain and feed conversion ratio. No significant interactions were found. However, for daily gain between arriving at the station and the end of the test, as well as for weight for age at the end of the test, genotype × batch interaction was significant (P < 0.05). The possible causes of these interactions are discussed. For slaughter characteristics genotype × month interactions were not of significance.

This paper considers some of the ‘non-nutritional’ aspects of feeding bulky diets to pigs, including behaviour, health and disease, climatic interactions and considerations of water and waste storage requirements. Aspects of behaviour relate chiefly to effects associated with the increased intake of fibrous diets needed to meet the animal's feed requirements and their subsequent digestion and utilisation. Addition of fibre to diets alleviates disease problems, such as gastric ulceration and gastro-enteritis, although the mode of action is not clearly understood. There are also important thermoregulatory characteristics resulting from the high heat increment of fibrous diets, making them more appropriate under colder conditions. The inclusion of fibrous feedstuffs appears to decrease water consumption, and hence urine volume, but increases the production of faeces of high particle size. This may create handling and disposal problems in slurry-based systems of production. There are therefore both positive and negative effects associated with the feeding of bulky diets to pigs.

New systems for estimating the requirements of ruminants for dietary protein involve separate estimates of the extent to which microbial and undegraded dietary protein meet the animal's net requirements for amino acids. The paper provides a brief review of the factors influencing both the synthesis of microbial protein and the amounts of dietary protein that escape the rumen undegraded. Although quantitative data on many of these factors are now emerging, the extensive nature of most sheep-production systems makes their application in a precise quantitative manner difficult. It is suggested that considerable improvements in production could be achieved by using the principles in a qualitative sense. For low-producing animals such as dry ewes, pregnant ewes up to a few weeks before lambing, and ‘store’ lambs, microbial protein will meet the animal's net requirements for amino-acid nitrogen provided that the animals have not been previously subjected to a specific protein deficiency. In contrast, the maximal yield of microbial protein will not meet the net requirements of high-producing animals, such as young, fast-growing lambs, and ewes in the final few weeks of pregnancy and during early lactation. These animals require protein supplements which at least in part escape degradation in the rumen.

This paper reports the results of a study, on a random-breeding Merino flock maintained at Trangie, New South Wales, of the genetic relationship between ovulation rate ( OR ) at 4 ages (18, 30,42 and 54 months) and testicular diameter ( TDM ) at 3 ages (5, 8 and 12 months). Genetic correlations between OR and TDM were estimated from (i) dam-son covariances derived from Least Squares ANOVA methods (approximately 450 dam-son pairs utilized for estimation of each of the 12 covariances) and (ii) from paternal half-sib genetic covariances using Restricted Maximum Likelihood methods (30–100 sire groups with 5–10 male and female progeny per group). Genetic variances were estimated from the same flock. Generally the genetic correlations between the male and female traits at different ages did not differ significantly. The pooled estimate between OR and TDM was 0.35 ± 0.08 from the dam-son covariance method, and 0.16 ± 0.11 from the half-sib covariance method. The size of these estimates suggests that useful genetic response in ovulation rate would result from selection on testicular size in Merino flocks. The results of sheep selection experiments involving testicular size are discussed in the light of the new information arising from this study.

This paper outlines the major principles involved in beef production from grassland. It reviews the major management systems and discusses the factors influencing the variations in efficiency and profitability. The data and conclusions are largely based on information collected by the British Meat and Livestock Commission. The main aspects are: 1. (1) High concentrate prices are forcing farmers to use grass more efficiently. 2. (2) Beef systems can utilise a wide range of grassland types. In particular beef cows can use poor pastures in difficult environments. 3. (3) A brief outline of the United Kingdom beef industry is given together with detailed descriptions of different production systems. The choice of system should depend on the available physical and financial resources. 4. (4) These systems are based on target levels of performance, they are not rigid but may be adapted to suit individual farm situations. 5. (5) Within a single system there is a wide range is performance and profitability and a direct relationship between daily liveweight gain and gross margin per animal. It is important to obtain maximum gains during the grazing season. 6. (6) There is a wide variation in the effective use of grass. In practice there is no relationship between the use of nitrogen and output per hectare, nor between stocking rate and daily gain per animal. There is a strong relationship between stocking rate and gross margin per hectare. 7. (7) As more grass and less concentrates are used the growth rate decreases and the slaughter weight increases. Producers with the best financial results within a system use less feed but achieve better liveweight gains.

Literature on the genetic variation in Voluntary Feed Intake (VFI) and traits related to VFI under ad lib. and restricted feeding has been reviewed. Also differences between breeds and selection lines are reviewed and discussed. Heritability estimates of VFI show average values of 0.12–0.59, with larger variation on real ad lib. feeding compared to “to appetite” feeding twice a day. It is also concluded that the genetic correlation between feed intake and gain is higher under ad lib. feeding than under restricted feeding, and that genetic correlation between daily gain and feed/gain decreases from about −0.9 under restricted feeding to about −0.6 under ad lib. feeding. Results from a Norwegian selection experiment indicate that there is no correlated response in daily feed intake (feeding “to appetite”) when selecting on backfat and daily gain, while other selection experiments, where feed conversion ratio has been the major component of the selection index, show reduced appetite. The present paper discusses the danger of reduced appetite in selection programmes that maximize short-term economic gain, and the importance of selection objectives and feeding regime on the genetic correlations between VFI and other production traits. A comparison is also made between population parameters of Norwegian and Danish Landrace pigs.

Several Danish investigations were carried out in order to elucidate the influence of nutrition, sex and slaughter weight on the body composition in pigs. In this paper we discuss whether selection of breeding animals should be based mainly on: (1) per cent meat in the carcass, (2) a combination of per cent meat, daily gain and feed consumption per kg live weight gain, or maybe better, (3) a combination of per cent meat and feed consumption per kg meat produced. Investigations comprising five different energy and protein levels and 1100 pigs slaughtered at live weights varying from 80 to 120 kg showed that both feeding intensity and slaughter weight influenced the carcass composition. Increasing feeding intensity and increasing slaughter weight caused a deterioration in the ratio between meat and subcutaneous fat. The feeding intensity had only little influence on kg meat produced whereas increasing feeding intensity caused an increase in kg subcutaneous fat produced. The females contained more meat than did the male castrates. Besides, the deterioration in carcass composition due to increasing slaughter weight and feeding intensity were lower in the females than in the male castrates. Daily gain increased with increasing feeding intensity. The investigations indicate maximal protein synthesis to take place within the live weight area of 90–100 kg. High correlations were found between the chemical composition of the different anatomical fractions in 90-kg pigs. The empty pigs (live weight minus the content of the digestive tract) weighed on average 80.8 kg, of which 42.0% was dry matter. The dry matter contained 41.1% protein, 51.1% chemical fat, 7.7% ash and 7080 kcal per kg. The meat fraction contained 55% of the protein, 30% of the chemical fat and 38% of the energy in the empty pigs.

Fattening of young boars in practice does not develop because of the occurrence of boar odour. In this paper a survey is given of the experiments in this field in The Netherlands. A consumer test involving 720 families divided into four groups judging cutlets or belly cuts from boars or gilts revealed that only a low percentage of the consumers were able to recognize boar odour. It should be taken into account that the boars used in this test had a strong boar odour. Besides that an expert panel considered smoked sausages acceptable in which meat and fat from boars with a strong boar odour was mixed up to a certain extent: up till 25% if consumed cold and between 6 and 12% if consumed warm. The incidence of boar taint as ascertained by meat inspection services in about 2 200 boars was very low: about 6% had a slight odour and only about 1% had a strong odour. Unexpected was the finding that there was no difference in frequency between the boars below and beyond 80 kg carcass weight. In spite of these findings the few consumers sensitive to boar odour should be protected. Pilot experiments with the use of a handsealer in the slaughterline are encouraging, so that boar carcasses with a strong odour may be selected already in the slaughterline. Based on the results of the fattening experiments in The Netherlands the economical advantage of fattening boars over hogs has been calculated. With 10.5 million slaughter pigs in 1972 the profit should have been about 75 million guilders. It is stated that sufficient evidence seems to be available to convince the authorities that removal of statutory bars to fattening uncastrated males should be considered at international and national levels.