Introduction

Reduced quality diets and removal of in-feed antibiotics negatively impacted nursery performance but not days to market or carcass characteristics (Skinner et al., 2014). C.L. Levesque of the University of Guelph and co-authors there and at the University of Illinois-Urbana Champaign.

Physiological mechanisms involved in periods of reduced and improved growth could be related to digestive capacity and digestive enzyme activity (Levesque et al., 2012a). Results of denatured gradient gel electrophoresis of ileal microbial community diversity suggested that post-weaning nutrition had a long-term effect and permanently altered ileal mucosa-associated but not ileal digesta, microbiota composition (Levesque et al., 2012b).

The objectives of this study were to:

1. describe the ileal bacterial profile during periods of reduced and compensatory growth and
2. determine whether early nutritional insult permanently altered the profile of ileal mucosa bacterial populations.

Materials and Methods

Forty-eight pigs, weaned at 21±1 day of age (6.4 ± 0.3kg bodyweight), were fed diets ad libitum containing either high (H) or low (L) quality protein sources with (A+) or without (A-) chlorotetracycline for six weeks in a three-phase regime (Phase 1, 7 days; Phase 2, 14 days; Phase 3, 21 days).

The H diets contained highly digestible protein sources, whereas, the L diets were primarily corn-soybean meal based diets with a small amount of whey protein and fishmeal in Phase 1.

Pigs were killed at two and eight weeks post-weaning and a 40-cm section of the distal ileum was taken for DNA extraction of mucosa-associated bacteria.

Ileal sections were rinsed, washed vigorously to remove mucosal bacteria and the wash was centrifuged to pellet the cells. Total DNA was extracted using a commercially available kit (Powersoil® DNA isolation kit). After PCR amplification, pyrosequencing of the PCR amplicons was performed using a 454 Genome Sequencer. Data presented as sequence percentage at each taxonomic level were analysed as repeated measures using the MIXED procedure of SAS.

Results

Mucosal bacteria clustered more closely by weekk post-weaning than starter diet treatment and there was no starter diet effect on bacterial diversity at week 2 or 8.

Firmicutes made up 91 and 96 per cent of total reads at weeks 2 and 8, respectively. Bacterial genera (expressed as percentage of sequences) in ileal mucosa of pigs collected at two and eight weeks of age indicated Lactobacillus were more abundant at week 2 and Clostridium were more abundant at week 8 post-weaning (Figure 1).

Figure 1. Bacterial genera (expressed as percentage of sequences) in ileal mucosa of pigs collected at 2 and 8 weeks of age fed High- or Low-quality protein with (A+) or without (A-) in-feed antibiotic

Regardless of week post-weaning, Clostridium, Lactobacillus, Sarcina and Streptococcus were the predominant genera. The proportion of Clostridium paraputrificum increased (P=0.003) from week 2 to 8 in pigs fed L (0.8 versus 13 ± 2 per cent) but did not change in pigs fed H (3 versus 6 ± 2 per cent; Table 1).

The proportion of Clostridium leptum decreased (P=0.02) from weeks 2 to 8 in pigs fed L (27 versus 1 ± 6 per cent) but did not change in pigs fed H (11 versus 5 ± 6 per cent). Furthermore, the proportion of Sarcina genus tended to decline from week 2 to 8 in pigs fed Low but tended to increase with post-weaning in pigs fed H diet (P=0.08).

Discussion and Implications

Ileal mucosa bacterial profiles were affected more by week post-weaning than by nursery diet, concluded Levesque and co-authors.

The impact of nursery diet quality was primarily at the species level. The increase in potentially beneficial bacteria and decrease in potentially pathogenic bacteria at week 8 in pigs on the low-quality diet may, in part, explain the compensatory growth observed at week 8 in these pigs.

This further stresses the importance of considering long-term changes in gut microflora when evaluating feeding strategies for young pigs, added the scientists.

References

• Skinner L.D., C.L. Levesque, D. Wey, M. Rudar, J. Zhu, S. Hooda and C.F.M. de Lange. 2014. Impact of nursery feeding program on subsequent growth performance, carcass quality, meat quality, physical and chemical body composition of growing-finishing pigs. J. Anim. Sci. Accepted.
• Levesque C.L., H. Yu, J. Gong and C.F.M. de Lange. 2012b. Ileal mucosa-associated, but not digesta, bacterial profiles in grower pigs are influenced by nutrition and use of antibiotics for starter pigs. J Anim Sci. 90 Suppl 4:448-50.
• Levesque C.L, L. Skinner, J. Zhu and C.F.M. de Lange. 2012a. Dynamic changes in digestive capability may contribute to compensatory growth following a nutritional insult in newly-weaned pigs. J Anim Sci. 90 Suppl 4:236-8.

Acknowledgement: Financial support for this research was provided by Ontario Pork, NSERC and OMAF/MRA. Technical assistance provided by Emily Miller, Julia Zhu and Doug Wey, is gratefully acknowledged.

Reference

Levesque C.L., S. Hooda, K.S. Swanson and C.F.M. de Lange. 2014. Mucosal bacteria associated with periods of reduced and compensatory growth in pigs. Proceedings of 33rd Centralia Swine Research Update. II-27–II-28.

Further Reading

Read other papers from the Centralia Swine Research Update 2014 by clicking here.

July 2014