Summary

A total of 400 nursery pigs (initially 12.5 lb) were used in a 20-day study to evaluate the effects of varying porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae (M-hyo) vaccination timing on growth performance of pigs fed commercial segregated early weaning (SEW) and transition diets from four different sources.

At weaning (day 0), pigs were blocked by weight and randomly allotted to one of eight treatments. Treatments were arranged in a 2 × 4 factorial on the basis of vaccination timing (0 or 8 days after weaning) and diet source (A, B, C or D). There were five pigs per pen and 10 pens per treatment.

Initially, SEW and transition diets were budgeted at 1 and 5 lb/pig, respectively. The SEW and transition diets were formulated to similar Kansas State University specifications but made by different manufacturers. Feeders were emptied on day 8, and a common phase 2 diet was fed for the remainder of the trial. On days 0, 4, 8 and 20, pigs were weighed and feed disappearance was measured to determine average daily gain (ADG), average daily feed intake (ADFI) and feed conversion rate (F/G).

Diet source influenced (P<0.001) ADG during the first 4 d of the trial. Pigs fed diet B had increased (P< .001) body weight (BW) (day 4) and ADG (days 0 to 4) than pigs fed all other diets, and diet D pigs exhibited increased ADG compared to pigs fed diet C. On day 8, diet source effects remained significant (P≤0.02) for pig weights (day 8) as well as ADG and ADFI (days 4 to 8 and 0 to 8). Pigs fed diet A had higher (P<0.01) ADG (days 4 to 8) than pigs fed the other three diet sources. Pigs fed diets A and B had similar ADFI but their ADFI (days 4 to 8) was greater (P≤0.02) than that of pigs fed diets C and D. There were no effects of diet source from days 8 to 20.

Pigs vaccinated on day 0 had lower (P<0.01) BW (day 8) and ADG and ADFI (days 4 to 8 and days 0 to 8) than pigs vaccinated on day 8. From days 8 to 20, pigs vaccinated on day 8 had lower (P=0.05) ADG.

Overall (days 0 to 20), diet source and vaccine timing did not influence growth performance, although pigs fed diet C had a numeric decrease (P=0.06) in ADFI. Nursery pigs in this trial were initially affected by both SEW/transition diet source and vaccination timing, but the influence of these factors lessened with time. Despite the transient nature of these effects, however, data obtained during this trial indicate that nursery pig growth performance is affected by diet source and vaccine timing immediately post-weaning, and these factors should be taken into consideration when managing weaning groups.

Introduction

Positive growth performance of nursery pigs is an essential component of successful swine production. However, recent reports from field observations indicate that some producers have experienced difficulty in starting or maintaining weaned pigs on feed, which results in decreased performance and production.

These reports seem to coincide with widespread adoption of porcine circovirus type 2 (PCV2) vaccination in growing pigs. Many weaned pigs receive PCV2 and other vaccinations at or near the time of weaning, though vaccination timing is not consistent in the swine industry. Other management factors affect pig performance and have been well characterised in research reports. For instance, it is well known that different diet formulations affect pig performance in the nursery. However, there is limited data on the potential effect of diet source. It has been suggested that nursery diet sources and vaccination timing may be important factors influencing this post-weaning problem.

The objective of this study was to investigate the effects of diet source as well as PCV2 and Mycoplasma hyopneumoniae (M-hyo) vaccination timing on pig growth performance.

Procedures

A total of 400 weaned pigs (31 gilts and 369 barrows) were used in a 20-day growth trial. Pigs were blocked by weaning weights (12.5 lb average) and randomly allotted to one of eight treatments. Because of the uneven number of gilts, 7 of the 8 treatments groups within one block contained four gilts each, and the remaining group contained three gilts.

Initially, each pen contained five pigs, and there were 10 pens per treatment. Treatments included segregated early weaning (SEW)/transition diet source (A, B, C or D) and vaccination timing (0 or 8 days after weaning). The SEW and transition diets were obtained from 4 commercial sources, and each diet was formulated to similar specifications (Table 1). At weaning (day 0), each pen received 1 lb per pig of SEW diet, and SEW diets were placed in the feeders at allotment. Transition diets were added to the feeders on top of the SEW diet and fed until day 8 (approximately 3 lb per pig). On day 8, feeders were emptied and refilled with a common phase 2 diet, which was fed for the duration of the trial.

Pigs were vaccinated intramuscularly with commercially available PCV2 (Circumvent, Intervet) and M-hyo (Respisure 1; Pfizer) vaccines on day 0 or 8 after weaning. The vaccines were administered according to label instructions. Pigs were weighed on days 0, 4, 8 and 20, and feeders were weighed on day 4, 8 and 20 to determine feed disappearance. From this data, average daily gain (ADG), average daily feed intake (ADFI) and feed conversion rate (F/G) were calculated.

Data were analysed as a randomized complete block design by using the PROC GLIMMIX procedure of SAS. Pen was considered the experimental unit for this analysis. Differences between treatments were determined by using least squares means (P<0.05)

Results

There were no significant (P<0.05) interactions observed between diet source and vaccine timing during this trial (Table 2). However, there was a trend (P=0.07) toward a diet source and vaccine timing interaction effect on F/G between days 0 and 8. For pigs fed diet B, the day 0 vaccinates had improved F/G compared with pigs that were not vaccinated until day 8. In contrast, day 0 vaccinates fed diets A and C demonstrated poorer F/G during the first 8 days of the trial than their counterparts that were vaccinated on day 8. This interaction trend disappeared after day 8, and no additional trends or significant interactions were observed during the remainder of the trial.

From days 0 to 4, pigs fed diet B had greater (P<0.001) ADG than pigs fed the other three diet sources (Table 3). Pigs fed diet D also had greater (P<0.05) ADG than pigs fed diet C, with pigs fed diet A being intermediate. The improved gain resulted in pigs fed diet B having heavier (P<0.001) average weights on day 4 than pigs fed the other diets. From days 4 to 8, pigs fed diet A had greater ADG (P<0.002) than pigs fed the other diets. Pigs fed diets A and C had greater (P<0.02) ADFI than pigs fed diets B and D. For the overall period when SEW and transition diets were fed (days 0 to 8), pigs fed diet C had lower (P<0.001) ADG and ADFI than pigs fed diets A and B, with pigs fed diet D being intermediate. As a result of the differences in ADG, pigs fed diets A and B were heavier (P<0.001) on day 8 than pigs fed diet C.

Diet sources fed from days 0 to 8 did not influence pig performance from day 8 to 20, when all pigs were fed a common diet. Al-though a trend (P = 0.06) was observed for a diet effect from days 0 to 20 for ADFI (indicating increased intake for pigs fed diet A and B compared with pigs fed diet C), the differences between diets sources from days 0 to 8 were not substantial enough to cause a lasting effect on pig performance in the second phase of the trial or overall. Because SEW and transition diets were formulated to similar specifications, the transient effects of diet source seen in the first phase of the trial may be due to diet ingredient quality and source as well as manufacturing differences between the commercial suppliers.

Vaccinating pigs with PCV2 and M-hyo vaccines on day 0 decreased (P≤0.01) ADG and ADFI from days 4 to 8 and 0 to 8 and pig weights (day 8; Table 4). From days 8 to 20 after weaning, the pigs vaccinated on day 8 grew slower (P=0.05) than those vaccinated at weaning (day 0).

According to this data, vaccination caused a temporary reduction in the growth performance of both day 0 and 8 vaccinates. Because of the stresses of vaccination, this transient decrease in performance is expected but because the pigs were not weighed as often during phase 2 (day 8 to 20) as during phase 1 (day 0 to 8), it is not possible to determine whether one vaccine timing treatment group was more severely affected immediately post-vaccination. However, because previous research has indicated that growth performance in the first week after weaning is a risk factor for subsequent nursery performance, the authors speculate that the decrease in performance around the time of weaning may have a greater potential for longer term effects than a decrease in performance in subsequent phases of the nursery period.

Overall (days 0 to 20), diet source and vaccination timing did not significantly affect growth performance of nursery pigs. However, performance was significantly affected by both of these factors throughout the first phase of the trial, indicating that diet source and vaccination do play a role in growth of nursery pigs during certain periods. Because pig weight and feed disappearance data were not collected as often during phase 2 as during phase 1, further studies investigating diet source and vaccine timing should be conducted to gain a better understanding of their effects on growth performance.

It is evident that these factors do influence nursery pig growth performance to some extent; thus, vaccine timing and diet source should be considered when making health and management decisions for weaning groups.

Further Reading

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