Although the farrowing process has an impact on postnatal piglet survivability and growth performance, information on factors that influence the farrowing process under field conditions is rare. The objective of the study was to determine factors influencing the duration of farrowing and birth intervals in Large White×Landrace crossbred sows. Data were collected from the Pig Industry Board, Acturus, Zimbabwe. The durations of farrowing were log transformed to normalize them, while birth intervals remained skewed after the transformation. As a result, Friedman's test was used to analyse for factors affecting birth intervals. The mean duration of farrowing was 217 min. Number of piglets born alive (NBA), average birth weight and the presence or absence of stillbirths influenced ( P<0·05) the duration of farrowing. The total number of piglets born (NBT) and order of piglets significantly influenced birth intervals ( P<0·05). There was wide variation in birth intervals, with the within-litter coefficient of variation ranging from 50 to 140 percent. The relationship between birth interval and order of birth was: Y=0·1011x2−1·771x+37·917 ( P<0·05). Relative birth order, expressed as a proportion of the total number of piglets born, also showed a significant quadratic relationship with birth interval: Y=0·0021x2−0·121x+23·952 ( P<0·05). The study found that relative birth order, NBA and NBT play an important rôle in influencing birth intervals and duration of farrowing, while parity and piglet weight do not. Logarithmic transformation failed to normalise data on birth intervals, highlighting their highly skewed nature.

Sensor feeding is a liquid feeding system for fattening pigs that is operated with a restricted animal/feeding-place ratio (AFR). The aim of the present study was to quantify the effect of three different AFRs (4:1, 7:1 and 13:1, calculated with a feeding space of 33 cm per animal) on the performance and behaviour of fattening pigs (mean initial weight 26·3 (s.d. 3·3) kg, live weight at slaughter 102 (s.d. 5) kg). The pigs were housed in groups of 40 and each AFR was tested with seven groups (21 groups in total). The daily weight gain of the individual pigs was calculated from the beginning of the experiments until slaughter. Additionally, the lean meat percentage was recorded (AutoFOM). Feeding behaviour was observed by means of 24-h video recording at the ages of 14 and 17 weeks with scan sampling every 5 min. The daily weight gain decreased with increasing AFR ( P<0·01) and females had lower weight gains than barrows ( P<0·001). The lean meat proportion was influenced by the AFR ( P<0·01) and sex of the pigs ( P<0·001). Proportions were highest with the AFR 13:1 and in females. The average number of pigs feeding simultaneously was highest for the AFR of 4:1 ( P<0·01). Moreover, the ingestion rate per day (kg/min) increased with increasing AFR ( P<0·05). The average number of pigs waiting behind other pigs feeding at the trough was highest with the AFR 13:1 ( P<0·001).In conclusion, growth performance and pig behaviour were negatively affected by an AFR of 13:1, which cannot be recommended for use with this feeding system. With an AFR of 4:1 lean meat values were low.

The effects of nutrition on patterns of live-weight change, hair follicle activity, moult, hormone profiles and associated activities of monodeiodinase enzyme types II and III (MDII and MDIII) in cashmere goats were investigated. From 1 week before the winter solstice (mid December), one group of 15 animals was given a ration designed to provide 2·0 × live weight maintenance requirements (high; H) while a second, similar, group was given 0·8 × live weight maintenance requirements (low; L). After approximately 3 months, L animals had significantly lower mean live weights (P<0·01) than H animals. This was associated with lower (P<0·05) overall mean hair follicle activity in L than H animals during the March to May period and a lower overall mean moult score during March and April in L animals (P<0·01) but a similar mean date of moult onset. Mean concentrations of all of the hormones measured exhibited significant changes (P<0·01) with date of sampling. Overall mean concentrations of insulin, tri-iodothyronine and thyroxine did not differ with treatment but, compared with L animals, H animals exhibited higher mean concentrations of prolactin in April and May (P<0·05) and of insulin-like growth factor-1 in December and January (P<0·001). Rates of activity of MDII and MDIII in skin differed with date (P<0·001) but were not significantly affected by nutritional treatment. The MDIII/MDII ratio differed (P=0·05) with month but was significantly higher (P<0·05) in L than H animals in January, only. It is concluded that the reduction in hair follicle activity and the slower onset of moult associated with reduced nutrition were unlikely to be controlled, directly, by differences in activities of MDII or MDIII in skin tissue.

A serial slaughter trial was carried out to examine the developmental change of physical and chemical body composition in pigs highly selected for lean content. A total of 48 pigs (17 females and 31 castrated males) were serially slaughtered and chemically analysed. Eight pigs were slaughtered at 20, 30, 60, 90, 120 and 140 kg live weight, (LW) respectively. The carcass was chilled and the left carcass side was dissected into the primal carcass cuts ham, loin, shoulder, belly and neck. Each primal carcass cut was further dissected into lean tissue, bones and rind. Additionally, the physical and chemical body composition was obtained for the total empty body as well as for the three fractions soft tissue, bones and viscera. Viscera included the organs, blood, empty intestinal tract and leaf fat. The relationship between physical or chemical body composition and empty body weight (EBWT) at slaughter was assessed using allometric equations (log10y=log10a+b log10 EBWT). Dressing percentage increased from 69·4 to 85·2% at 20 to 120 kg and then decreased to 83·1% at 140 kg LW, whereas percentage of soft tissue, bones and viscera changed from 23·5 to 33·0%, 10·1 to 6·3% and 14·7 to 10·3%, respectively, during the entire growth period. Substantial changes in proportional weights of carcass cuts on the left carcass side were obtained for loin (10·5 to 17·5%) and belly (11·3 to 13·8%) during growth from 20 to 140 kg. Soft tissue fraction showed an allometric coefficient above 1 ( b=1·14) reflecting higher growth rate in relation to the total empty body. The coefficients for the fractions bones and viscera were substantially below 1 with b=0·77 and 0·79, respectively, indicating substantial lower growth relative to growth of the total empty body. Lean tissue allometric growth rate of different primal cuts ranged from b=1·02 (neck) to 1·28 (belly), whereas rates of components associated with fat tissue growth rate ranged from b=0·62 (rind of belly) to 1·79 (backfat). For organs, allometric growth rate ranged from b=0·61 (liver) to 0·90 (spleen). For the entire empty body, allometric accretion rate was 1·01, 1·75, 1·02 and 0·85 for protein, lipid, ash and water, respectively. Extreme increase in lipid deposition was obtained during growth from 120 to 140 kg growth. This was strongly associated with an increase in backfat and leaf fat in this period. Interestingly, breeds selected for high leanness such as Piétrain sired progeny showed an extreme increase in lipid accretion at a range of LW from 120 to 140 kg, which indicates that selection has only postponed the lipid deposition to an higher weight compared with the normally used final weight of 100 kg on the performance test. The estimates obtained for allometric growth rates of primal carcass cuts, body tissue and chemical body composition can be used to predict changes in weight of carcass cuts, determine selection goals concerning lean tissue growth, food intake capacity, etc. and generally as input parameters for pig growth models that can be used to improve the efficiency of the entire pig production system for pigs highly selected for lean content.

Three hundred young rabbits were divided into three groups at weaning and given ad libitum a control diet (C), or an experimental diet in which 0·20 of control diet was substituted by maize ear (E) or by whole maize plant (P) in order to examine their effects on fattening rabbits performance, carcass characteristics and meat quality. No significant differences were found in live-weight gain (45 g/day) or in food intake between diets but food conversion ratio was higher in the P group (2·4 g dry matter (DM) per g gain) than in E group (2·2 g DM per g gain). The rate of mortality was similar in the three groups. No differences between groups on live weight (2152 g) or in the digestive tract weight (437 g) were found and the dressing yield was similar in the three groups. At constant carcass weight, the carcasses of rabbits of the P group had lesser lumbar circumference and higher length to circumference ratio (P<0·0001) than of the C or E groups. No differences were found in the weights of liver or thoracic viscera, but kidneys of rabbits of P group were lighter than of the C or E groups. No differences between groups were found in the weights of scapular fat, perirenal fat, forelegs or thoracic cage, but the loin of rabbits of P group was heavier (291 v. 286 g) than in the other groups. Meat of rabbits P had higher L* and b* parameters of colour and higher water-holding capacity (P=0·003) but the meat of rabbits of the control group had less lipids (31 v. 36 g/kg meat) and more moisture (739 v. 735 g/kg meat) than of the experimental groups. The proportion of protein was higher in E group than in P group. Intra and intermuscular fat of hind leg meat from rabbits ‘maize’ substituted was more monounsaturated than control rabbits (34·2 v. 32·5 g·100 g lipids) and had lesser saturated: monounsaturated ratio (1·2 v. 1·3) indicating a more desirable meat from a nutritional point of view, but had less n-3 fatty acid content. Loin meat of the rabbits given E and P diets seems more tender than one fed conventionally (10·4 v. 11·4 kg) and meat of the rabbits ‘whole maize plant’ had more grass flavour (P=0·009) which is a positive factor for acceptability of consumers.

The experiment was undertaken to quantify the α and γ-tocopherols accumulation in muscle and backfat from Iberian pigs given food free-range as affected by the time of free-range feeding or the weight gained during the fattening in free-range. Pigs were given their food in a free-range production system with pasture and acorns (Quercus rotundifolia) for different periods of time: 46 days (free-range 3), 83 days (free-range 2) and 111 days (free-range 1). A control was given food free-range for 0 days. In addition another experiment was developed to determinate the effect of the the weight gained on the tocopherols accumulation at a similar period of time (111 days) given food free-range: one group gained 68·7 kg of weight (free-range A) and the other 43·6 kg (free-range B). The concentration of γ-tocopherol significantly (P<0·0001) increased after 83 days of feeding in the longissimus dorsi (LD) and biceps femoris (BF) muscles, and after 111 days in the inner and outer backfat layers. The concentration of α-tocopherol was not statistically affected by the days of free-range feeding in any case. Iberian pigs that put on more weight had significantly (P< 0·0001) higher concentration of α and γ-tocopherols in the inner and outer backfat layers, and α-tocopherol in the BF muscle than those given food free-range B. However, no differences were detected in the proportion of α-tocopherol in the LD and γ-tocopherol in the LD and BF. The γ-tocopherol content of LD and BF muscles depending on the days of feeding were adjusted to linear and quadratic regressions (R2=0·8705 and 0·8697, respectively), while the outer and inner backfat layers were linear equations (R2=0·8480 and 0·8119, respectively). However, the γ-tocopherol concentration as affected by the weight gained in free-range showed in all tissues a linear and a quadratic trend that were adjusted to exponential responses. The α-tocopherol content was affected by the γ-tocopherol concentration in muscle and outer backfat layer. The tocopherol concentration (α and γ-tocopherols) in the backfat layers may discriminate better between the pigs of high quality that were given food free-range for a long period of time and those that stayed an intermediate period. However, to discriminate between the pigs on formulated food and those given food free-range, the quantification of the γ-tocopherol concentration in muscle could be a better indicator.

The objective of the present study was to test the reliability of the analysis method of the reflectance spectrum of fat in the zone of light absorption by carotenoid pigments developed in lambs to trace grass feeding in calves. Six feeding treatments were compared in suckling calves: ad libitum cocksfoot hay plus ad libitum concentrate or half level of ad libitum concentrate (HH and HL), ad libitum cut grass plus ad libitum concentrate or half level of ad libitum concentrate (GH and GL), ad libitum highland grazed grass plus ad libitum concentrate (PH); ad libitum medium quality cocksfoot hay plus dam's milk (C0). Groups HH, HL, GH, GL and PH were slaughtered at approximately 10 months of age, after 150 days of experimental feeding diet. C0 calves were slaughtered at the beginning of the experiment at approximately 6 months of age. The concentration of carotenoids was analysed by HPLC on diets and calves' plasma at slaughter. The reflectance spectrum of perirenal and subcutaneous fat were measured at slaughter and expressed as AVI units. Plasma carotenoid content was higher (P<0·05) in PH and GL calves than in HH, HL and GH calves. There was an effect (P<0·05) of feeding treatment and measurement site on AVI. Values obtained for perirenal fat were higher (P<0·05) than those obtained for subcutaneous fat. For plasma carotenoid content and for AVI values in both fat tissues there was no overlapping between hay-fed calves on the one hand and GL or grazing calves on the other hand. However, there was some overlapping between hay-fed calves and GH calves. For plasma carotenoid content, values for C0 calves overlapped with values of GH and GL calves. For both fat tissues AVI values of C0 calves overlapped with values of HH, HL, GH and GL calves. AVI of cut grass fed calves (GH and GL groups) increased linearly (P<0·05) with average daily grass intake for both tissues considered. AVI in subcutaneous fat tissue decreased linearly (P<0·05) with average daily concentrate intake but this relation was not significant for AVI in perirenal fat (P>0·05). Plasma carotenoid concentration and the reflectance spectrum of the fat in the zone of light absorption by carotenoid pigments could be used to trace grass feeding in calves. Results obtained in this study suggest that different fatty tissues could differ in their reliability and interest for traceability of grass-feeding, depending on the animal age and production system.

A total of 166 crossbred does were used to study the possible long term effect of two types of crossbred does (H1 v. H2, old and current generations, respectively) from the cross of different generations of lines selected for litter size, the use of a feeding programme based on a low-energy diet during the rearing and the administration of a high-energy diet during reproductive life, on the performance and body condition of multiparous pregnant does. Selection did not affect the live weight (LW) of does at the effective artificial insemination (AI; 4257 g), the LW change (+12·3 g/day) and food intake (172 g dry matter (DM) per day) until the 28th day of pregnancy. However, H2 does showed greater LW losses during the pre-partum period than H1 does (120+g; P<0·05), perhaps related to their higher prolificacy (+1·1 total pups born; P<0·05). H2 does showed a higher perirenal fat thickness (PFT) at first AI (+0·12 mm; P<0·05) than H1 does, these differences disappearing at effective AI. Females given a high-energy reproduction diet showed a lower LW at effective AI than those receiving a medium-energy diet (4210, 4305 g, respectively; P<0·05). However, type of reproduction diet did not affect the LW and PFT changes of pregnancy does, reaching partum with a similar PFT (8·83 v. 8·93 mm) and maintaining the differences in LW. Pregnant does given high-energy diet consumed 20 g DM and 1·4 g digestible protein per day less than does receiving medium-energy diet until the 28th day of pregnancy, but their digestible energy (DE) intake was significantly higher (+78 kJ DE per day; P<0·05). Does given high-energy diet showed a significantly lower litter size at birth (−0·7 pups; P<0·05), although there were no significant differences in the number of pups born alive (9·54 and 9·76 pups for high and medium-energy diets, respectively). Pups from does given high-energy diet were slightly weightier than those from medium-energy diet (+5·4 g; P<0·05). Multiparous pregnant does that received a low-energy diet ad libitum during the rearing period and first pregnancy showed a higher LW at effective AI (+137 g LW; P<0·05) but a lower PFT (−0·26 mm; P<0·05) than those females that received a medium-energy diet restricted during this same period. These differences were maintained at parturition (+142 g LW and −0·20 mm; P<0·05). Feeding programme during rearing affected neither the food intake of multiparous pregnant does until the 28th day of pregnancy, nor the litter size and weight at birth. The interval between parturitions was not affected by the selection for litter size or the reproduction diet received, but was longer for does that received the low-energy diet ad libitum during the rearing period (+2·9 days; P<0·05). In conclusion, rabbit selection programmes by litter size seem to be working well, but high energy reproduction diets, frequently used to cover their higher energy requirements, must be used carefully out of lactation in the long term to avoid a reduction in litter size.

A total of 166 crossbred does were used to study the possible long-term effect of two types of crossbred does (H1 v. H2, old and current generations, respectively) from the cross of different generations of lines selected for litter size, the use of a rearing programme based on a low-energy diet, and the administration of a high-energy diet during reproductive life, on the performance and body condition of lactating rabbit does and their litters until slaughter. The body condition of the reproductive rabbit does increased in the successive cycles to the fourth parturition, being maintained from this moment on. Animals more selected for litter size at weaning presented a greater food intake (+3%; P<0·05) and milk yield (+6%; P<0·05) during the first 21 days of lactation, which could be related to greater maternal aptitude. The difference in the weight of pups at slaughter time (+24 g for H2 respect to H1 pups) was one third lower than that expected from the generation response of the paternal line (0·45 g/day), perhaps related to the different enteropathy incidence depending on the genetic type. The use of a high-energy diet during the reproduction period increased the milk yield (+22%; P<0·05) of does, as the growth (+16 g at weaning day; P<0·05) and survival index (+2%; P<0·05) of the litters during lactation, but could produce a more sudden weaning of pups as a consequence of their lower pre-weaning food intake (−42%; P<0·05), which has been related with a greater health risk index during the growing period (+4·2%; P<0·05). Reproductive does given a high fibre diet during the rearing period (from 3 kg live weight to 28th day of the first pregnancy) reached parturition with a higher live weight than does that received a moderate energy diet restricted during this same period (+142 g; P<0·05). All other parameters controlled for the lactating does and their litters were not affected by the type of diet received during the rearing period. Females that were not effectively mated at first AI (11 days post partum) showed a greater increase in their perirenal fat thickness between partum and the 11th day of lactation than those lactating females that showed an effective mating (+0·22 v. +0·37 mm, respectively; P<0·05).

In this paper we report on the results of a recent dissection experiment in The Netherlands where prediction formulae for the percentage lean meat in pig carcasses with the Hennessy Grading Probe (HGP) and a vision system (from now on referred to as Vision) were determined. Predictions with the HGP were based on one fat and one muscle depth measurement only, while predictions with Vision were based on as many as 115 direct and derived measurements. The data from this dissection experiment were used to illustrate the statistical calculations involved in relation to the number of carcass measurements. Prediction with instruments that gather a large number of measurements per carcass is not covered by the present European Community (EC) regulations. Therefore the calculations were conducted according to new regulations for statistical methodology in pig carcass grading that are expected to be adopted by the EC in the near future. The calculations included consideration of 3 subpopulations (females, entire males and castrated males). The Vision data were also used to show that ordinary regression after selection of a subset of carcass measurements severely under estimates the accuracy of prediction: instruments and associated prediction formulae are seemingly much more accurate than they truly are. When standard regression methods are used for instruments that gather a large number of measurements, there is a considerable risk that measurement instruments will be selected for the wrong reasons. Accuracy of approved instruments may not even comply with the EC-regulations, with poor consequences for harmonization within the EC.

Fat quality, in particular, firmness is a main contributor to meat appearance, shelf life, taste, and human health. The current study was conducted to examine the fluctuation and criteria of porcine fat firmness. Several physiochemical methods were performed on 237 porcine perirenal fat samples that were obtained randomly from a commercial market. The relationship between perirenal fat and the middle subcutaneous fat layer was investigated to predict carcass fat quality. Each physiochemical property of the perirenal fat showed considerable variation as a 40-fold difference in firmness was observed between the most extreme samples. Differences between these extremes were 19°C in melting point, 0·0043 for refractive index, and 18 g per 100 g fatty acid methyl esters for saturated fatty acids (SFA) concentration. Strong curvilinear relationships were found between Instron and sensory firmness scores (R=0·90–0·96, no.=24). On the basis of these relationships, classification of the perirenal fats obtained from the commercial market was defined. Fats possessing firmness values of less than 7 N have undesirable fat quality, whereas fat samples with values greater than 16 N were not popular in the market. From these data, we conclude that fats of 7–16 N in firmness value were preferred by consumers. Firmness values of perirenal fat samples correlated significantly with the stearic acid (C18:0) and SFA concentrations of samples of the middle subcutaneous fat layer (r=0·68, 0·57, P<0·01). These results indicate that there are wide fluctuations in the porcine fat quality, and that fats ranging in Instron firmness values between 7 and 16 N are most acceptable to consumers. And, subcutaneous fat may prove to be a valuable indicator of whole body pork fat quality.

Twenty-four castrated males were used to study the effect of breed (Large White v. Creole (LW v. CR)) and feeding level (0·70, 0·80, 0·90, and 1·00 ad libitum) on growth performance and protein deposition (PD) and lipid deposition (LD) between 30 and 60 kg in growing pigs under tropical climatic conditions; the CR pigs are raised in the Caribbean area and can be qualified as fat and slow growing pigs. Daily protein and amino acids supplies were calculated to be non-limiting for protein gain. Total PD and LD were measured according to the comparative slaughter technique. Digestibility coefficients of energy and nutrients were estimated over a 10-day period at 45 kg live weight. Neither the breed nor the feeding level influenced the apparent digestibility coefficients of dietary nutrients; only energy digestibility was increased at reduced feeding levels (P<0·05). Average daily gain increased linearly with the increase of metabolizable energy (ME) intake and the slope of the relationship was lower in CR than in LW pigs (30·4 v. 36·6 g per additional MJ ME). The food conversion ratio was not affected by feeding level but it was significantly higher in CR than in LW pigs (2·88 v. 2·36 kg /kg; P<0·001). Daily PD increased with ME intake according to a linear relationship in both breeds and the slope was significantly affected by breed (3·1 v. 4·2 g/MJ ME in CR and LW pigs, respectively; P<0·001). In contrast, the increase of LD and total energy retained with ME were higher in CR than in LW pigs (8·4 v. 6·4 g/MJ and 0·40 v. 0·36 MJ/ MJ ME, respectively; P<0·001).

Embryo transfer studies have demonstrated that high plane feeding in early pregnancy is detrimental to the successful establishment of pregnancy in adolescent but not mature ewes. To further examine this relationship with ewes that conceive naturally and to investigate its effects on foetal development, 102 Greyface and Texel×Greyface ewes (body condition score (BCS) 3·8) and 114 Texel×Greyface adolescent ewes (BCS 3·3) were allocated to one of three treatments following a synchronized mating. From day 1 to 31 of pregnancy, animals were offered grass nuts (10·2 MJ metabolizable energy (ME) per kg dry matter (DM); 163 g crude protein per kg DM) at one of three levels to supply approximately 2·0 (H); 1·0 (M) and 0·6 (L) of their predicted ME requirements for maintenance. Increasing the post-mating plane of nutrition resulted in significant increases in ewe live weight (P<0·001) and BCS (P<0·001) during the treatment period. When diets were standardized for all animals during mid pregnancy (days 31 to 105), L ewes gained more live weight (P<0·05) and BCS (P<0·001) than H ewes. Early pregnancy nutrition had no effect on the conception rate of mature ewes; however adolescent ewes on the H and M treatments had lower conception rates (P<0·05) than those offered the L diet (0·59, 0·61 and 0·82 respectively). As a result, L adolescent ewes tended to have a higher mean total lamb birth weight per ewe mated (P=0·09) although lamb output at weaning was not influenced by plane of nutrition. Lambs born from adolescent mothers had lower lamb birth weights (P<0·001) and a shorter mean head length, crown-rump length and thoracic girth (P<0·001). Foetuses from H ewes had longer hind legs than those from L ewes on day 83 of gestation (P<0·05) and at term (P<0·05). The results of this study suggest that allowing adolescent but not mature ewes to lose live weight and body condition can increase the proportion of productive ewes following a natural service.