Effects of Feeding Probiotic or Chlortetracycline or a Combination on Nursery Pig Growth Performance

A total of 300 nursery pigs (initial BW 5.9±0.05 kg) were used to determine the effects of feeding chlortetracycline (CTC) with or without probiotics on nursery pig performance. Pigs were weaned at approximately 21-d of age and randomly allotted to pens based on initial BW. Pigs were fed a common pelleted starter diet for 4 d and then weighed, and pens were allotted, in a randomized complete block design based on BW, to 1 of 6 dietary treatments with 10 replications/treatment. The treatments were arranged in a 2×3 factorial with main effects of CTC (0 vs. 440 ppm from d 0 to 42) and probiotic (0, 0.05% Bioplus 2B [Chr. Hansen USA, Inc., Milwaukee, WI], or 0.05% Poultry Star [Biomin America, Inc., San Antonio, TX]). Experimental diets were fed in 2 phases (Phase 1: d 0 to 14 and Phase 2: d 14 to 42) and all diets were fed in meal form. Diets were corn-soybean meal based and were formulated to meet the pigs’ nutrient requirements for each phase of this study. The Phase 1 diets contained specialty protein sources while Phase 2 diets did not. On d 15 and 29, CTC was removed from CTC diets and non-medicated feed was fed for 1 day. For overall performance, there were no interactions (P>0.05) between probiotics and CTC. Pigs fed CTC had improved (P<0.001) ADG, ADFI, and overall BW compared with those fed diets without CTC. Adding Poultry Star to the diet increased (P<0.05) ADFI and BW from d 0 to 14. However there was no difference in ADG or ADFI for the overall d 0 to 42 period. In conclusion, CTC improved nursery pig performance, but there were no consistent benefits of feeding either probiotic alone or in combination with CTC.

CTC	-	+	-	+	-	+
Bioplus 2B1	-	-	+	+	-	-		Probability < P
Poultry Star1	-	-	-	-	+	+	SEM	CTC
d 0 to 42
ADG, g	424	469	405	482	445	473	13.16	0.001
ADFI, g	644	726	625	727	687	728	16.22	0.001
G:F	0.658	0.645	0.645	0.664	0.648	0.650	0.0003	0.795
BW, kg
d 42	24.2	25.6	23.6	26.1	24.8	25.8	0.052	0.001
1No significant interactive or main effects of BioPlus 2B or Poultry Star (P>0.05).