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Management of Weaned Pigs 2: Providing additional wet feed for weaners

by 5m Editor
28 April 2002, at 12:00am

By Niamh E. O'Connell, Violet E. Beattie and R. Norman Weatherup - In the second part of the authors two part study into the management of weaned pigs the aim was to assess whether providing additional wet feed at regular intervals in a highly accessible trough improves the performance of weaned pigs.

General introduction

Rearing weaned pigs involves a balance between achieving optimum performance while minimising costs. Achieving high feed intake is central to obtaining optimum performance in weaned pigs, and efficient food conversion is central to minimising costs. Newly-weaned pigs often show low levels of feed intake during the post weaning period, this may reflect difficulty adapting to a solid diet and to using a feeder for the first time (Pluske and Williams 1996). In addition, stress associated with separation from dam and littermates, mixing with unfamiliar animals and relocation to a new environment may contribute to reduced feed intake.

As a consequence there is usually a 'growth check' post weaning, where growth rates can fall from 300 g/day in the week prior to weaning to 100 g/day in the week after weaning. This growth check represents a major production penalty for a number of reasons. Firstly, growth rate in the immediate post weaning period has been shown to affect lifetime performance and even carcase quality (Hutton, 1989). In addition, poor growth rates can extend the amount of time pigs spend in expensive weaner accommodation and can also reduce physiological development. As a result pigs are more susceptible to disease (Partridge, 1989).

The way in which pigs are managed in the post weaning period largely determines performance and cost of production within a given breed. There are a number of factors to be considered, including weaning age, ambient temperature, stocking rate, group size, mixing strategy, feeding regime, and pen and feeder design. The onus is on the manager to manipulate these factors in order to maximise production efficiency. It is becoming increasingly necessary to achieve this while minimising labour and capital expenditure.

The research discussed in this paper involves investigations into two areas of management of weaned pigs: Increasing group size, and Providing additional wet feed (this article). The overall objective is to investigate methods of improving production efficiency in weaned pigs.

This article focuses on the second of these two investigations:

Providing additional wet feed for weaners

Introduction

It has been suggested that one of the factors which leads to low feed intake by pigs during the post weaning period is difficulty adapting to a completely solid diet (Fraser et al., 1998). A possible method of overcoming this is to provide piglets with liquid or 'wet' feed. This has been shown to stimulate feed intake in the post weaning period (Jensen and Mikkelsen, 1998). This increased intake may have additional benefits in terms of helping to maintain the digestive capacity of the gut which can decrease after weaning (Pluske et al., 1997). One of the problems with liquid feeding, however, is poor food conversion due to high levels of wastage (Kornegay et al., 1981).

Feed intake may also be stimulated in the post weaning period by manipulating the way in which feed is presented. Newly-weaned piglets may prefer to feed simultaneously at intervals as they did on the sow prior to weaning. This is not possible with some commercial feeders, however, which offer a limited number of individual feeding spaces. This may lead to problems with access to the feeder which may be exacerbated in groups of small pigs which appear to have a slower rate of eating (O'Connell et al., 2001b).

The aim of this study was to assess whether providing additional wet feed at regular intervals in a highly accessible trough improves the performance of weaned pigs. In addition, the effect of providing additional wet feed for groups of small and large pigs was also assessed in order to determine whether the trough was of particular benefit to small rather than large pigs.

Material and methods

Pre experimental treatment All piglets were born in crated farrowing accommodation and were offered a commercially available creep feed from 10 days of age in a forward creep area. Piglets were weaned at 4 weeks of age and allocated to treatments.

Treatments

This experiment was carried out in two separate studies. In study A pigs were assigned to one of two treatments:
  1. trough containing additional wet feed,
  2. control treatment with no trough.
In study B pigs were assigned to one of four treatments:
  1. small pigs (i.e. <8 kg on average) with access to trough,
  2. small pigs with no access to trough,
  3. large pigs (i.e. >10 kg on average) with access to trough,
  4. large pigs with no access to trough.

Animals and housing

In study A, 240 pigs were mixed into groups of 15 animals at weaning. The groups were balanced for live weight, gender and litter and were assigned randomly to treatment. In study B, 360 pigs were mixed into groups of 15 at weaning and allocated to treatment. The groups were allocated to treatment ensuring that, within each weight category, treatments were balanced for gender, weight and litter.

The pigs were housed in pens measuring 1.1 x 3.5 m with plastic slatted floors. Between 4 and 7 weeks of age the pigs had access to a kennel area heated by a radiant heater. At 7 weeks of age the pigs were moved to identical pens (in the same building) but without the kennel area. The pigs remained here until the end of stage 2 at 11 weeks of age.

Each group of pigs was offered feed ad libitum from two single-space wet and dry feeders. In the trough treatment, 150 g/day of the same feed was also available from a metal trough (length x width x height = 762 x 152 x 76 mm). The trough was placed in the feeding area of the pen (Figure 1) and was secured to the slats with bolts. The feed which was placed in the trough was mixed in a 2:1 ratio with water at ambient temperature and was added to the trough three times daily for 5 days post weaning in study 1, and for 4 days post weaning in study 2. The trough was cleaned out on each occasion before feed was added. In all treatments water was available from a nipple drinker in each single-space feeder and also from a nipple drinker mounted on the wall of the pen.

Diets offered between 4 and 7 weeks of age consisted of commercial starter and stage 1 feeds in pelleted form. From 8 to 11 weeks of age pigs were offered a pelleted cereal/soya based diet ad libitum. This contained 14.2 MJ DE/kg and 22% crude protein and was manufactured at the Agricultural Research Institute of Northern Ireland.

Figure 1: Layout of pen used during post weaning period
(T= trough containing wet feed, F=single-space wet and dry feeders)

Measurements

Pigs were individually weighed at 4, 7 and 11 weeks of age, and feed intake was recorded daily for the first week after weaning and weekly thereafter until 11 weeks of age. Individual growth rates and group feed intake and food conversion ratios were calculated for stage 1 (4 to 7 weeks of age) and stage 2 (7 to 11 weeks of age). Average within-pen variations in daily liveweight gain was calculated for both treatments in study A between 4 and 11 weeks of age.

In addition, feeding behaviour at the single-space feeders was recorded for the first 5 days post weaning in study A using video recorders (2 frames per second). Video tapes were later analysed to determine the number of pigs feeding at the feeder at 10 minute intervals.

Results and Discussion

Effects of providing additional trough
In both studies A and B there were no significant differences between the trough and control treatment in live weight at 4, 7 or 11 weeks of age, the mean values for both studies being 8.8, 15.6 and 33.6 kg respectively (Table 1).

Table 1
Mean live weight (kg) at 4, 7 and 11 weeks of age in studies A and B
Treatment Weight category
Age Control Trough s.e.m. P Heavy Light s.e.m. P
Study A
4 weeks 8.7 8.7 0.00 NS - - - -
7 weeks 15.3 15.2 0.13 NS - - - -
11 weeks 33.4 33.0 0.28 NS - - - -
Study B
4 weeks 8.9 8.9 - NS 10.1 7.6 0.01 <0.001
7 weeks 15.9 15.9 - NS 17.3 14.5 0.17 <0.001
11 weeks 34.1 33.8 - NS 35.9 32.0 0.34 <0.001

In study A pigs with access to the additional trough showed higher levels of feed intake on days 1 and 4 post weaning than pigs without access to the trough (P<0.001 and P<0.05 respectively) (Table 2). There was also a trend for feed intake to be higher on days 2 and 3 post weaning when pigs had access to the additional trough compared to pigs without access (P<0.1). Mean daily feed intake was 7% higher during stage 1 when pigs had access to the additional trough (P<0.05).

In study B feed intake was significantly higher on days 1 and 2 post weaning when the additional trough was provided rather than in the control treatment (P<0.001) (Table 3). However mean feed intake levels during stage 1 and stage 2 did not differ significantly between the trough and no trough treatments in study B.

Providing additional wet feed in a trough had no significant effect on growth rate during stages 1 or 2 in studies A or B. Within-pen variation in daily live weight gain was similar between the trough and no trough treatments (0.0099 and 0.0125 kg/day2 respectively) in study A. In addition, there was no significant effect of providing an additional trough on food conversion during stages 1 and 2 in studies A or B, however there was a 13% poorer food conversion ratio during stage 1 of study A in the trough treatment (Table 2).

Table 2:
The effect of providing additional wet feed in a highly accessible trough on the performance of pigs between 4 & 10 weeks of age in study A
Control Trough s.e.m. P Daily feed intake (g)
Day 1 15 34 1.9 <0.001
Day 2 40 55 5.8 NS
Day 3 80 107 9.3 NS
Day 4 124 156 10.2 <0.05
Day 5 164 158 12.2 NS
Day 6 195 177 14.0 NS
Day 7 218 218 11.1 NS
Stage 1 367 392 5.2 <0.05
Stage 2 1119 1059 28.6 NS
Stages 1 and 2 785 773 13.4 NS
Daily liveweight gain (g)
Stage 1 343 321 14.0 NS
Stage 2 648 652 12.3 NS
Stages 1 and 2 515 510 4.6 NS
Food conversion ratio
Stage 1 1.09 1.23 0.043 NS
Stage 2 1.73 1.63 0.053 NS
Stages 1 and 2 1.53 1.52 0.019 NS

These results show that providing additional feed in a highly accessible trough leads to modest increases in apparent feed intake during the immediate post-weaning period. It should be noted, however, that in the present study the term intake refers to the total amount of feed used and therefore includes both consumed and wasted feed. The fact that increased levels of apparent feed intake in the trough treatment in study A were not accompanied by increased growth rates suggests there was more feed wastage in this treatment. This is supported by the poorer food conversion ratio shown during stage 1 in study A. Previous research at this Institute has also shown greater wastage when feed was offered from shared troughs rather than single-space wet and dry feeders (O'Connell et al., 2001a). This increased wastage with the trough treatment in the present study appeared to be due to the pigs pushing the feed off the trough as there was rarely any feed left in the trough and it was rarely fouled in. It is possible that the lack of rooting substrate in the pens meant that pigs used the trough to perform rooting behaviour in addition to feeding (Beattie et al., 2001).

Apparent feed intake from the trough accounted for 60, 57, 30, 20 and 17% of total apparent feed intake from days 1 to 5 respectively. This was reflected in a reduced average daily number of animals observed at the single-space feeders when pigs had access to a trough during the first week after weaning in study A (trough treatment: 5.7, control treatment 6.5, s.e.m. 0.24 pigs, P<0.05) (values shown are square root values taken in order to normalise data). The decline shown in the proportion of feed used from the trough over the first 5 days post weaning may reflect a development in feeding behaviour. It is possible that the ability to perform synchronous feeding behaviour becomes less important, and the ability to eat undisturbed by penmates more important during the first week after weaning. In addition, it is also possible that all pigs had learned to use the single-space feeder by the end of the first week and were therefore less reliant on the trough.

The lack of improvement in performance in the present study suggests that there is no overall benefit in providing newly-weaned pigs with additional wet feed in a trough. It is possible, however, that the trough may have benefited certain pigs in the group without affecting overall performance. Evidence from study 1 (increasing group size) suggests that small pigs may have difficulty gaining access to feeders in small groups, therefore these pigs may have benefited by the addition of the trough in the present study.

Effect of providing additional trough for groups of small pigs

The effects of weaning weight and of provision of wet feed in a trough in study B are given in Table 3. There were no significant interactions between weaning weight and providing additional wet feed on any of the parameters measured. Therefore providing wet feed in a highly accessible trough does not provide any additional advantage to groups of small pigs over groups of large pigs. However the average weaning weight of small pigs in the present study was 7.6 kg which may be greater than the average weaning weight of small pigs on commercial units. It is possible that providing wet feed may have greater benefits for pigs weaned at lighter weights whose digestive systems are less physiologically mature.

Table 3:
The effect of providing additional wet feed in a highly accessible trough and of size at weaning on pig performance in study B
Feed Size
Control Trough P Large Small s.e.m. P
Food intake (g/d)
Day 1 15 34 <0.001 25 24 1.5 NS
Day 2 45 69 <0.001 59 55 3.8 NS
Day 3 102 103 NS 107 99 6.6 NS
Day 4 149 155 NS 158 146 6.3 NS
Day 5 178 168 NS 175 171 7.4 NS
Day 6 211 215 NS 220 206 9.8 NS
Day 7 269 262 NS 271 259 10.8 NS
Stage 1 398 400 NS 415 383 10.2 <0.05
Stage 2 1128 1089 NS 1146 1071 20.3 <0.05
Stages 1 & 2 817 796 NS 835 778 13.6 <0.01
Growth rate (g/d)
Stage 1 348 350 NS 356 342 8.3 NS
Stage 2 677 664 NS 691 650 10.0 <0.05
Stages 1 & 2 537 530 NS 548 519 7.1 <0.05
Food conversion ratio
Stage 1 1.15 1.15 NS 1.17 1.12 0.015 <0.05
Stage 2 1.67 1.65 NS 1.66 1.65 0.026 NS
Stage 1 & 2 1.52 1.50 NS 1.53 1.50 0.019 NS

Management

Use of the troughs resulted in increased capital expenditure and increased labour with no overall improvement in performance. In addition, use of troughs reduced housing capacity. Each trough occupies 0.12 m2 which is over half the space allowance of a stage 1 weaner (0.2 m2). The troughs also reduced the unobstructed area in the pen and care may be needed in the location of the troughs. If the trough is placed in the feeding area then it may block access to the feeders, and if it is in the dunging area then it may lead to increased dunging in the sleeping or feeding areas, or increased fouling of the trough.

Conclusions

  • Increased labour and capital expenditure
  • No improvement in performance
  • No particular benefit for groups of small pigs

General summary for management of weaned pigs

General summary for management of weaned pigs
Increasing group size Providing additional wet feed
Stage 1 growth no effect no effect
Stage 1 food conversion ratio no effect poorer
Stage 2 growth no effect no effect
Stage 2 food conversion ratio poorer no effect
Variability in groups reduced no effect
Capital expenditure reduced increased
Labour no effect increased
Production efficiency Improved Reduced

Acknowledgements

The authors gratefully acknowledge funding for this research from the Pig Production Development Committee in conjunction with the Ulster Farmer's Union Pigs Committee, and from the Department of Agriculture and Rural Development for Northern Ireland. We also wish to thank the staff of the pig unit at the Agricultural Research Institute of Northern Ireland for excellent technical assistance and care of the animals.
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