C. T. Whittemore

Reproductive performance, body weight and body condition of breeding sows with differing body fatness at parturition, differing nutrition during lactation, and differing litter size

One hundred and two Large White × Landrace Fl hybrid sows were allocated over four parities in a factorial design to two levels of target P2 backfat thickness at parturition (20 mm, F v. 12 mm, T), two levels of lactation feeding {ad libitum, H v. 3 kg/day, L), and two sizes of sucking litter (six v. 10). Sows attained 13 mm P2 when first mated at 126 kg live weight. Fatness (P2, mm) at weaning was significantly influenced by target fatness at parturition (14·2 v. 9·3), lactation feeding level (13·7 v. 10·0), and litter size (12·7 v. 11·0). Changes in backfat (P2, mm) during 28-day lactation were significantly influenced by target fatness at parturition (—5·0 v. —2·5), lactation feeding (-2 0 v. —5·4), and litter size (—2·9 v. -4·6). Sow live weight (kg) at weaning was significantly influenced by target fatness at parturition (211 v. 192), lactation feeding (218 v. 186), and litter size (208 v. 196). Changes in live weight (kg) during 28-day lactation were significantly influenced by target fatness at parturition (—26 v. — 12), lactation feeding (—5 v. —31), and litter size (—12 v. —25). With multiparous sows only, total food intake during 28-day lactation was negatively related to total food intake in pregnancy. Change in backfat (P2, mm) during 28-day lactation = -0·28 - 0·27 P2 at parturition + 0·04 lactation food intake — 0·50 litter size. Change in live weight (kg) during 28-day lactation = -3·8 — 0·15 live weight post partum + 0·36 lactation food intake — 3·3 litter size. Sows with target fat levels of 20 mm P2 at parturition had better food conversion efficiencies than sows with target fat levels of 12 mm. Target fatness at parturition, and especially lactation food intake, but not litter size, significantly influenced the interval (days) from weaning to oestrus in parity 1 (9·1 v. 14·2 and 7·8 v. 15·3, but 11·6 v. 11·5), while n i subsequent parities only litter size influenced the interval (days) from weaning to oestrus (6·0 v. 8·0). Birth weight (kg) of piglets was influenced only marginally by target fatness at parturition (1·4 v. 1·2) in parity 1, and not by the other factors, or in subsequent parities. Piglet growth rate was affected by both target fatness at parturition and litter size, but by lactation feeding level only in the last week of lactation. The relationship between fatness at weaning (mm) and the weaning to oestrus interval (days) for primiparous sows can be expressed as 26·6 — 1·28 P2. High level feeding in lactation imparted production and efficiency benefit in both primiparous and multiparous sows, while pregnancy feeding to a target of 20 mm rather than 12 mm at parturition was of benefit for primiparous sows.

Nutrition reproduction interactions in primiparous sows

Abstract Selection for genotypes of pigs with increased growth rate, larger mature size, reduced levels of body fatness and greater prolificacy has resulted in a need to reassess nutritional requirements of primiparous sows, there being a substantial effect on all phases of the reproductive cycle. These effects are greater than in the multiparous sow, probably because of marked differences in growth ambitions which create a conflict of interest for the metabolism of the immature breeding sow. Where feeding is adequate and conception not premature, there is no evidence to support special increases or decreases in nutrient supply to enhance ovulation rate, embryo survival, or late gestation foetal growth. There is no proven influence of gestation feed intake on lactation feed intake independent of body fatness at parturition. Lactation feed intake limitation renders the primiparous sow prone to severe maternal lipid and protein losses required in the support of lactation. Conventional intakes are usually below those required daily to attain energy and nitrogen balance. Excessive negative balances will utilise available labile body lipid and body protein, and reproductive efficacy is compromised. Overall, it would appear unwise to allow P2 backfat depth to fall below 14 mm or to rise above 25 mm (lipid:protein ratio > 1:1 and

Effect of group size on feeding behaviour, social behaviour, and performance of growing pigs using single-space feeders

Use of computerized feed intake recording (CFIR) equipment allows automatic recording of individual feed intake of animals kept in groups. However, current CFIR systems have only one feeding space per social group which may lead to increased competition for access to the feeder. The present experiment examined the effect of increased competition around a single-space feeder on individual performance and behaviour by manipulating the number of pigs per feeder. 150 male crossbred pigs were penned at 34 ± 0.3 kg (mean ± SE) in groups of 5, 10, 15, or 20 for 29 days with one single-space computerized feeder per pen and 1.06 m2/pig. Pigs kept in groups of 20 made fewer but longer visits to the feeder and ate more and faster than pigs kept in the smaller groups (7.1 vs. 14.3 visits/day, P < 0.01; 6.91 vs. 4.64 min/visit, P < 0.05; 214 vs. 119 g/visit, P < 0.05; 31.6 vs. 25.9 g/min, P < 0.05; means of group size 20 vs. means of group size 5, 10, and 15, respectively). No differences were found between group sizes in daily feed intake, daily live-weight gain and feed conversion ratio (overall means: 1490 g/day, 725 g/ day and 2.09 g/g, respectively). Mean number of aggressive interactions initiated and won were significantly lower for the two largest group sizes on the day of grouping. A rank index based on pairwise aggressive interactions was not correlated to any of the production or feeding behaviour variables. No significant effect of group size was found on mean number of attempts to displace other pigs from the feeder. The change in feeding pattern in the largest groups appears to represent an adaptation to the constraint placed on their feeding behaviour and they succeed in adjusting to the lack of feeding space as there were no significant differences between groups in production variables. A correlation between performance and social behaviour may have been disguised by environmental factors such as space allowance and straw provision or, alternatively, aggression and growth may be independent characteristics.

Technical review of the energy and protein requirements of growing pigs: food intake

A review of work reported in the literature was used to present quantitative descriptions of protein use in the growing pig. These are detailed in the text, which also points to preferred values, and to anomalies and lacunae. The review was prepared with the objective of allowing from its content the inclusive and quantitative modelling of amino acid requirement. Requirement was approached as the sum of the component factors: maintenance and protein retention. Ileal true digestible protein and amino acid requirements are presented in a form consistent with that forwarded for energy. Thus both energy and protein elements can be conceptualized within a single coherent framework. Priority uses for absorbed amino acids were assumed to be (a) to support endogenous protein losses resultant from the passage of food and incomplete re-absorption prior to the terminal ileum, (b) to replace lost hair and skin, and (c) to cover the basic maintenance losses which will occur as a result of minimal protein turn-over even when protein retention is zero. The bulk of the protein requirement was directly linked to the daily rate of protein retention, for which the linear-plateau response was accepted. For determination of the maximum rate of protein retention the Gompertz function was proposed, although the use of a single value throughout the growth period was not dismissed. The balance of amino acids for protein retention is specified as different from that for maintenance. Central to the approach was the proposal that the inefficiency of use of ileal digested ideal protein, even when not supplied in excess, was an expression of protein losses occurring as a result of protein turn-over. The requirement for the satisfaction of the losses from protein turn-over occurring as a consequence of protein retention, and therefore additional to the requirements for maintenance, was identified. Quantification was attempted with sufficient success to warrant its inclusion into requirement estimation. It was concluded that this element addressed previously inadequately explained protein utilization inefficiencies. Algorithms are presented based upon protein turn-over which appear to be consistent with empirical findings.

Impact of biotechnology on (cross)breeding programmes in pigs.

Abstract Crossbreeding programmes in pigs exploit between breed complementarity of additive genetic effects and heterosis generated by non-additive genetic effects. Within breed, improvement programmes may focus on additive effects and hence the enhancement of complementarity, but non-additive variation is not generally used in within line selection or for mate selection at the multiplier or commercial level. In this paper, we discuss the impact of new biotechnological tools, particularly molecular markers, multiple ovulation and embryo transfer (MOET), and cloning, on structures and methods in crossbreeding. At the between line level, genetic marker information could allow better prediction of heterosis in novel crosses from information on genetic distances. Within the crossbreeding structure, the same technique might be applied at the multiplier and commercial level to exploit specific combining abilities of particular animals. Combining simple MOET and cloning protocols could radically alter the dissemination of crossbreeding benefits and their delivery to the farmer. The combination of MOET, cloning and genomic tools could result in speed genetics programmes, i.e. fast introgression and recurrent selection methods. Thus, the ultimate impact of biotechnology will be increased rates of progress, efficient use of variation, reduced genetic lag, and the removal of one or two tiers in the breeding pyramid. The costs of new technologies are discussed briefly.

Feeding behaviour of growing pigs using single or multi-space feeders

Most studies of the feeding behaviour of group housed growing pigs have used computerized single-space feeders, which result in a pig:trough ratio which differs from that found on commercial pig farms, where multi-space feeding troughs are used. The present experiment compared the feeding patterns of group housed, growing pigs given access to either a computerized single-space feeder or a four-space feeding trough. Eighty cross-bred entire male pigs (initial live-weight 32.3 ± 0.62 kg; mean ± s.e.) were allocated to groups of ten, and each group given access to one of the two feeder types. The feeding behaviour was measured automatically fro the single-space feeders, and determined for the four-space trough treatment from video tapes, where feeder visits were counted and timed, combined with daily weights of the food eaten per group. Pigs given access to a four-space trough visited the feeder much more frequently (84.5 vs. 14.3 visits day−1; s.e.d. = 5.3; P < 0.001), and for shorter durations (0.67 vs. 4.67 min per visit; s.e.d. = 0.36; P < 0.001), eating only a little per visit (24 vs. 149 g per visit; s.e.d. = 14; P < 0.001) compared with pigs kept in the groups given access to a computerized single-space feeder. High levels of allelomimetic feeding were shown by pigs using the four-space trough, with 61% of all visits initiated whilst one or more pigs were already feeding. Also, a higher proportion of visits were made adjacent to a feeding pig than would have been expected by change (0.59 vs. 0.50; P < 0.001). No significant differences were found between treatment in the rate of feeding or daily feeder occupation. The differences in feeding pattern did not result in differences in production variables in terms of daily feed intake, daily live-weight gain, and feed conversion ratio. A bout analysis was applied to the data using frequency distributions of length of intervals between visits. For pigs using the four-space trough visits could justifiably be collapsed into feeding bouts, whereas this was not the case for visits displayed by pigs using the single-space feeder. Pigs using the four-space trough showed a high frequency (0.64) of changes between spaces within each feeding bout. This may represent exploratory or sampling behaviour, which may aid the pig in obtaining a nutrient-sufficient diet should many different food items be available. Comparing feeding bouts from the four-space feeders to visits from the single-space feeders revealed no differences between the two types of feeders, indicating that single-space feeders constrain the feeding pattern mainly in terms of preventing changes between trough-spaces within bursts of feeding.

Growth of body components in young weaned pigs

Four experiments with 133 piglets of between 21 and 55 days of age were used to examine, by slaughter and chemical analysis, the composition of the body of young pigs. Following removal from the sow, the lipid content of the empty body decreased from about 15 to 7·6%, and in the subsequent 4 weeks had recovered only slightly to between 7·7 and 10·9%; with the exception of pigs with a particularly high intake of energy whose 42-day lipid content had increased to 13·2%. Where Y 3 was the lipid gain, X 1 the digestible energy intake (MJ) and X 2 the ratio of digestible energy to digestible crude protein (g), over all experiments Y3 = 7·83 X 1 + 4945 X 2 −1260. There was little change in the protein content of pigs consequent upon the effects of either removal from the sow, pig age, diet type or nutrient intake. Over all experiments and slaughter weights; P = 0·164 W −100, where P was the protein content of the body (g) and W the empty body weight (g). The efficiencies of conversion of digestible energy to energy gain in body protein and lipid were 0·36 and 0·33 respectively, associated with a constant (daily maintenance) term of 0·462 MJ ME/kg LW 0·75 . The low value for lipid is as would be expected for animals catabolizing lipid within the experimental period.

Effects of single-space feeder design on feeding behaviour and performance of growing pigs

Computerized food intake recording systems of various designs are used by research, centres and breeding companies to monitor the individual food intake of pigs kept in groups. In the present experiment, three feeder designs are compared in order to estimate the effect on performance and feeding behaviour. Ninety entire male pigs (34 (s.e. 0·6) kg) were allocated in three replicates to pens of 10 pigs; each pen containing one of three different feeder entrance designs: low (head-guard), medium (full-length standard race), and high (enclosed pneumatic race) protection against disturbance of the feeding pig. No significant differences were found between treatments in daily food intake, daily live-weight gain, food conversion ratio, number of visits per day and daily feeder occupation. Pigs with access to an enclosed race had longer visits than pigs on the two other treatments, and they also ate more per visit (4·8, 4·8 and 6·2 (s.e.d. = 0·37) min per visit; 172, 157, and 202 (s.e.d. = 11·1) g per visit; means of low, medium and high protection, respectively). The enclosed race was not only the most protective, it was also the most difficult to enter, and this decreased accessibility of the food may have given rise to the changed feeding pattern displayed by pigs using this type of race. Access to a feeder with low protection resulted in a faster rate of eating (36·9, 33·2, and 32·8 (s.e.d. = 0·82) g/min; means of low, medium and high protection, respectively) indicative of a more forced feeding behaviour.

The relationship between body dimensions of living pigs and their carcass composition.

The performance of a visual image analysis (VIA) system was tested with regards to its potential to determine in vivo carcass composition and conformation, either alone, or in conjunction with other in vivo measures such as live weight and backfat depth. Pigs of both sexes of a commercial type were reared and slaughtered at weights ranging from 50 to 120 kg. Feeding was ad libitum on diets ranging from 0.14 to 0.19 kgkg(-1) crude protein content to produce animals of a range of body condition. Two analyses were carried out: the first analysis addressed the relationship between dimensionless carcass and VIA indices; the second analysis assessed the relationship between carcass composition and VIA body shape using detrended carcass and VIA data, which were produced by removal of allometric growth trends. A statistically significant relationship (P<0.05) between in vivo VIA body size and shape and carcass muscle dimensions and composition was found for most body regions. Adjusted R(2) statistics ranged between 0.13 and 0.54 for relative fat weights and between 0.14 and 0.51 for relative lean weights. The predictive power of the regression models, indicated by R(2)-like statistics for prediction, was approximately 70% of the adjusted R(2) values. The descriptive and predictive powers of the corresponding models generally strengthened if VIA indices were combined with other in vivo measurements. The relationships between in vivo and carcass measures remained statistically significant (P<0.05) after removal of the growth trends, although adjusted R(2) statistics generally decreased. The predictive power of models corresponding to the detrended measures was, however, weak. The results show in vivo VIA measurements to be useful in the estimation of muscle size, carcass conformation and composition, all of which are of significant importance to the pig production, marketing and processing industries.

A case for size and shape scaling for understanding nutrient use in breeding sows and growing pigs

Abstract New Visual Image Analysis technologies now allow the hitherto unattainable measurement of animal size and shape. Knowledge of size and shape (and volume) in addition to weight gives new dimensions to pig description. Sow body condition, and consequent nutrient requirement, can be directly and objectively determined for the first time since weight was questioned as an adequate datum upon which to base sow feeding requirements. Relationships could now be drawn for a more direct determination of fitness for slaughter, and of nutrient requirements; in the latter case evidently for maintenance but, on reflection, also for growth. So familiar has the scale of weight become that it is ill appreciated that weight is often used not only for its own sake but rather as an indirect estimation of size and shape. This paper examines the value of the estimation of size and shape for animal description in relation to nutrient use; if not to replace weight entirely, then at least to augment it.