Summary For the last several decades, antimicrobial compounds have been used to promote piglet growth at weaning through the prevention of subclinical and clinical disease. There are, however, increasing concerns in relation to the development of antibiotic‐resistant bacterial strains and the potential of these and associated resistance genes to impact on human health. As a consequence, European Union (EU) banned the use of antibiotics as growth promoters in swine and livestock production on 1 January 2006. Furthermore, minerals such as zinc (Zn) and copper (Cu) are not feasible alternatives/replacements to antibiotics because their excretion is a possible threat to the environment. Consequently, there is a need to develop feeding programs to serve as a means for controlling problems associated with the weaning transition without using antimicrobial compounds. This review, therefore, is focused on some of nutritional strategies that are known to improve structure and function of gastrointestinal tract and (or) promote post‐weaning growth with special emphasis on probiotics, prebiotics, organic acids, trace minerals and dietary protein source and level.

This study evaluated the effect of feeding low protein (LP) diets for 7 or 14 d after weaning or a high protein (HP) diet for 14 d after weaning on postweaning diarrhea (PWD), indices of protein fermentation, and production in pigs infected or not infected per os with an enterotoxigenic strain of Escherichia coli. A total of 72 female pigs weaned at aged 21 d with initial BW of 5.9 ± 0.12 kg were used in a 3 × 2 factorial arrangement of treatments. The factors were 3 feeding regimens associated with different combinations of feeding duration and diet CP level: (i) HP diet (256 g of CP/kg) fed for 14 d after weaning, (ii) LP diet (175 g of CP/kg) fed for 7 d after weaning, and (iii) LP diet fed for 14 d after weaning; and infection or noninfection with an enterotoxigenic strain of E. coli (10 7 cfu/ mL, serotype O149:K91:K88) at 72, 96, and 120 h after weaning. The LP diets were fortified with crystalline Ile and Val to achieve an ideal AA pattern. A second-stage diet (213 g of CP/kg) was fed to pigs at the conclusion of each feeding regimen, and the study finished 4 wk after weaning. None of the diets contained antimicrobials. Feeding the LP diets decreased (P < 0.001) plasma urea nitrogen, fecal ammonia nitrogen concentrations, and the incidence of PWD, but increased (P = 0.001) fecal DM content compared with pigs fed HP in the 2-wk period after weaning. Infection increased shedding of β-hemolytic E. coli (P < 0.001), the incidence of PWD (P < 0.001), and fecal ammonia nitrogen concentrations (P < 0.01), but did not interact with feeding regimen, after weaning. Pigs challenged with E. coli grew more slowly (P < 0.001) and had decreased G:F (P < 0.01) compared with nonchallenged pigs in the 4-wk period after weaning. Feeding an LP diet for 7 or 14 d after weaning markedly reduced the incidence of PWD after infection with β-hemolytic E. coli. Infection was associated with decreased indices of protein fermentation in the distal gastrointestinal tract but did not compromise the growth of weaner pigs in the 4-wk period after weaning.

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Nutrient digestibility and the effect of high dietary inclusion of canola meals from Brassica napus black (BNB) and Brassica juncea yellow (BJY) on growing and weaned pigs performance were determined. In Exp.1, 6 ileal cannulated barrows (initial BW = 20.7 ± 1.5 kg) were used to determine the apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of AA in BNB and BJY. Pigs were allotted to diets containing either BNB or BJY as the sole source of protein in a crossover design to give 6 replicates per diet. The SID of all AA in BNB and BJY were similar. In Exp. 2, 168 weaned pigs (initial BW = 7.61 ± 0.76 kg) were assigned in a randomized complete block design to 7 diets (n = 24) consisting of a wheat-soybean meal-based control diet and 6 diets containing 5, 10 or 15% of canola meal derived from either BNB or BJY to determine the effect of different dietary inclusion on growth performance over a 28-d period postweaning. Diets were formulated to contain similar NE and SID of Lys. There were no differences in growth performance among treatments. In Exp. 3, 162 weaned pigs (initial BW = 7.26 ± 0.70 kg) were used to determine the effect of high BNB and BJY inclusion level without or with multicarbohydrase supplementation on growth performance and apparent total tract digestibility (ATTD) of CP, DM, and GE. A wheat-soybean meal-based control diet and 8 diets containing 20 and 25% of either BNB or BJY without or with added multi-carbohydrase were formulated (n = 18) to contain comparable NE and similar SID of Lys contents. Feeding the diets containing 25% of BNB or BJY supported similar growth performance as those containing 20%. The multi-carbohydrase had no effect on growth performance but improved (P < 0.05) the ATTD of DM, CP, and GE compared with those fed nonsupplemented diets irrespective of canola meal type. Diets containing 25% canola meal had lower (P < 0.05) ATTD of DM, CP, and GE regardless of canola meal type compared with the 20% canola meal diets. There was an interaction (P < 0.05) between canola meal type and inclusion level on ATTD of DM in which ATTD of DM decreased with increasing inclusion of both canola meal types. Results of the current study indicate that both BNB and BJY can be included up to 25% in weaned pig diets without compromising performance as long as the diets are formulated on an NE and SID of Lys basis. Also, enzyme addition improved the ATTD of CP, DM, and GE in weaned pigs in both BNB and BJY diets.