Probiotics and antibiotics as additives for sows and piglets during nursery phase

The purpose of this study was to evaluate the effects of the use of probiotics in diets for sows and piglets on performance and morphophysiologic parameters and the incidence of diarrhea in piglets during 28 days after weaning. A total of 120 pigs weaned at 21 days of age from 24 litters whose sows (primiparous) received probiotics or antibiotics from the 94th day of gestation until weaning. It was used a complete randomized design in a 2 × 3 factorial (probiotics or antibiotics for sows and three diets for piglets antibiotics, probiotics or probiotic-antibiotic combination) with four replicates of five animals to evaluate the performance and incidence of diarrhea. At 28 days of experiment, two animals from each plot were sacrificed for histological parameter measurement of the pH of the stomach, jejunum and cecum. The association antibiotics + probiotics in the diet of pigs resulted in greater weight gain and feed intake in animals born from of sows which received probiotics during the gestation and lactation phases. When females received antibiotics, the piglets receiving only probiotics showed higher consumption, but there were no differences for feed conversion. The use of antibiotics + probiotics in diets for piglets reduced the pH of the cecum and, when associated with the use of probiotics for sows, villous:crypt ratio in the jejunum increased. The use of growth promoters did not affect stomach pH neither the incidence of diarrhea. Supply of probiotics in the diet of sows during the gestation and lactation phases associated to the use in the diet of piglets after weaning is effective in maintaining animal performance, to histophysiological conditions in the gastrointestinal tract and control of diarrhea during the nursery phase.


Introduction
It is a general consensus that daily weight gain in the first week after weaning has an enormous impact on subsequent performance.Specific dietary additives are incorporated at this stage in order to improve performance and benefit the health of animals.In addition to antibiotics other additives have been also used as prebiotics, probiotics and corresponding combinations (synbiotics), and acidifying (Tokach et al., 1992) for decades.
At weaning, the pig is challenged in terms of nutritional, thermal, and emotional health, a fact that affects the behavior and the hormonal balance of the animals (Orgeur et al., 2002).Regarding to nutrition, milk is completely replaced by a diet usually dry and less digestible.With the loss of lactogenic immunity, transfer to a new housing and in many cases, the rearrangement of litters, the consumption of food becomes low and variable, contributing to the increased incidence of diarrhea.At the same time, there is an occurrence of atrophy and loss of villus in the small intestine due to colonization of pathogenic bacteria, leading to losses in digestion and absorption of nutrients.In many cases, it is necessary a period from 10 to 14 days for animal to recover the level of energy consumption as in the days prior to weaning.
In this context, the use of antibiotics as growth promoters has reduced the negative effects of early weaning (Budiño et al., 2005).However, the idea of abolishing the use of these substances with these purposes has forced the use of alternative substances, such as probiotics, which have also shown the ability to improve the performance of weanling pigs (Estienne et al., 2005), but not always with satisfactory results.
The idea that the pigs should be ready for weaning during lactation is solid among pig farmers.We also know that the health of pigs is directly related to the health of its mother, since the first bacteria that colonize the gastrointestinal tract of piglets are from the environment.
Furthermore, the prevention of diarrheal diseases, the concept of administration of live microorganisms that act by antagonizing pathogenic bacteria appears to be effective.The exact fashion in how this antagonism is manifested is not completely understood and it may occur through production of inhibitory compounds such as lactic acid or by competition for nutrients and adhesion sites (Alexopoulos et al., 2001).However, contrasting results illustrate the complexity of interactions between dietary components, the microbiota (and metabolites), the enterocytes and the local immune system (Lallès et al., 2007).
In this sense, the present study was conducted to evaluate the use of probiotics in the diets of mothers and piglets on performance, morphological and physiological parameters and incidence of diarrhea for 28 days after weaning.

Material and Methods
The experiment was conducted in the Departamento de Zootecnia at Universidade Federal de Lavras, Lavras, in southern Minas Gerais.
The beginning of the experiment used 24 gilts at 94 ± 2.3 days of gestation, housed in individual cages during gestation, where they remained until the 107th day of gestation.In this group, 12 received standard diet (control) and antibiotic (amoxicillin 50%, 400 g per tonne) and 12 received a diet containing probiotic (250 ppm -Table 1) instead of antibiotics, all at the daily quantity of 2.5 kilograms.After lactation, the animals began to receive rations of milk, also made for both groups.
During lactation, the litters of each group were distributed according to the diets of the sows in three groups: one group received antibiotics added to the diet (amoxicillin and colistin at 50% in 400 and 240 per ton, respectively), the other orally received probiotics at 1, 3, 12 and 21 days of age and added to the diet at the beginning of the treatment (1,000 ppm), and the third group received probiotics, also orally, on the same days and added to the diet (1,000 ppm) associated to the antibiotics.At the end of lactation, all piglets were weighed and transferred to the nursery.
In the nursery, 120 pigs originating from 24 litters were homogenized within each group of experimental diets, at initial weight of 6.19 + 0.72 kg.The animals were kept in groups of five in pens containing automatic feeder and pacifier type drinker and they were weighed at the beginning, at 14 and 28 days of nursery.The supplied rations followed the same protocol stipulated for lactating: antibiotic, probiotic and antibiotic-probiotic, at the sameconcentrations.

Bifidobacterium bifidum
3.33 x 10 6 Enterococcus faecium 1.66 x 10 6 Lactobacillus acidophilus 3.33 x 10 6 Lactobacillus plantarum 1.66 x 10 5 Source: Levels of product warranty.This phase used a completely randomized design in a 2 × 3 (piglets from mothers which were and were not fed probiotic and three experimental diets for piglets) scheme in a plot time-split (14 and 21 days of the experiment) with four replicates and five animals per pen (experimental unit) for performance in a randomized block in a 2 × 3 factorial with four replicates of two animals for measurement of histological parameters of jejunum and stomach and fecal pH.
The experimental diets for mothers (gestation and lactation) and pigs (initial and pre-starter) were formulated following the recommendations by Rostagno et al. (2005) (Table 2).
Diets were given ad libitum to the piglets.The supplied food and orts were weighed to determine consumption of each pen.Water was provided ad libitum throughout the experimental period.
For analysis of fecal score, the feces were placed daily in stalls on a scale from 0 to 3, in which 0 was adopted for normal stool and 3 for pasty stools.Figures 1 and 2 correspond to the stool with normal structure, but with discoloration, and pasty stools, respectively.
At 35 days of age (14 days of the experiment in the nursery), two pigs from each treatment were euthanized after desensitization power to analyze the pH of the stomach and cecum and to obtain samples of proximal jejunum.The measurement of pH was made using a pH meter F-1003 ® Bernauer.Samples of jejunum (approximately 4 inches) were washed in distilled water and fixed in Bouin's solution (saturated aqueous picric acid, formaldehyde and acetic acid) for 24 hours.After that time, the material was washed and preserved in 70% alcohol for future analysis.The preparation of the slides was done in a laboratory of the Departamento de Medicina Veterinária/UFLA, using the technique described by Junqueira & Junqueira (1983).
The analyzed variables were weight gain, average daily weight gain in the nursery, average daily feed intake, feed conversion, villus height, crypt depth and villous: crypt of the jejunum ratio, gastric pH and cecal and fecal score.The data were subjected to analysis of variance and F test to compare treatments between the headquarters and SNK at 5% to compare the diets of piglets.
For fecal score, nonparametric statistics were used since the data did not reach normality even after transformation.In this case, the data were submitted to a Chi-square test and means were compared by Kruskal-Wallis.
All tests were performed using the statistical computing Sisvar (Ferreira, 2000).
Moreover, considering all the piglets from mothers which received antibiotics in the diets, consumption by animals that received probiotic only in the initial phase was higher (P<0.05)when compared to the other.This same effect was not observed (P>0.05) when the animals were from mothers which received probiotics in the diets.
For feed conversion, there was interaction (P<0.05) between diet of the sows and diet of piglets (Table 3).At 14 days of nursery, it was observed that the piglets from mothers which received antibiotics during late gestation and lactation, use of antibiotics in the starter diet promoted (P<0.05)better result than the diets containing probiotics, while this effect was not observed (P> 0.05) in animals from mothers that received antibiotics.Comparing the combination antibiotic-probiotic for piglets, it was better (P>0.05) in animals from mothers which received a probiotic, which was not observed when antibiotic and probiotic was used alone in the diets of piglets.There was no effect (P>0.05) of additives or matrix or size at 28 days of nursery.Alexopoulos et al. (2001Alexopoulos et al. ( , 2004) ) observed increased weight gain up to 49 days of age in the group sow and piglets fed with probiotics.Similar results were obtained by Estienne et al. (2005), when the authors observed weight gain and satiety for weaning pigs after receiving probiotics and housed in a mixture of litters.However, Taras et al. (2006) found no effect of the probiotic on the performance of the animals after weaning.According to these studies, the variation in results obtained from the literature may be related to genetics, the strain used as probiotic and especially to environmental conditions.In the latter case, the health challenge that the animals are subjected may directly affect the effect of additives on the intestinal health of animals.
In this study, the use of Bifidobacterium bifidum, Enterococcus faecium, Lactobacillus acidophilus and Lactobacillus plantarum resulted in better performance after weaning when used in the diet of mothers during gestation /lactation and it can be used to replace antibiotics in initial and pre-starter diet of piglets.Moreover, the greatest weight gain of piglets fed antibiotic-probiotic, from breeders which received probiotics in the diet, suggests Table 3 -Piglets performance receiving additives in diet, from sows that were also treated with antibiotic or probiotic during gestation and lactation even greater benefits for the combined use of these additives in diets for mothers and piglets.Taras et al. (2007) observed that supplementation of diets with Bacillus cereus var.toyoi did not increase weight gain but it improved feed conversion of piglets weaned at approximately around 8%.Furthermore, using Enterococcus faecium did not result in significant effect on the overall performance of the animals in the same stage.
In relation to histological parameters of the jejunum (Table 4), it was shown that the use of antibiotics in diet for sows resulted (P<0.05) in maximal height of villus in piglets at 14 days after weaning (35 days of age).This does not necessarily result in better animal performance.There was interaction (P<0.05) for crypt depth and villous:crypt ratio.When probiotic was used in the diet of the mothers, the use of probiotics associated with antibiotics in the diets of pigs allowed (P<0.05) a lower depth of crypts and higher villus:crypt ratio.These same results were observed (P<0.05) when using antibiotics in the diet for piglets and sows.
These results are consistent with those obtained by Utiyama et al. ( 2006), who did not report the beneficial effects of probiotics to improve gut integrity in piglets but according to these authors, the greatest benefit would be exercised for villus by antibiotics reducing the microbial metabolism and the decrease of metabolites, which would be toxic to the intestinal epithelium.Moreover, Budiño et al. (2005) found no difference between antibiotics and probiotics for villus height in the jejunum of piglets at 14 days after weaning.Lodemann et al. (2008) observed discrete effects of probiotics on the absorptive and secretory properties of the epithelium of the mucosa in the jejunum and intestinal transport.Only a small increase in the transport of L-glutamine was observed in the group treated with probiotics.
It was not observed effects (P>0.05) for the use of additives in diets of mothers and piglets in the stomach pH of animals slaughtered 14 days after weaning (Table 5).However, the use of probiotics associated with antibiotics resulted in cecal pH lower than when antibiotics were used only in the diet of piglets.This low pH could be related to better intestinal health of animals, however, there were no correlation among these results with the performance of animals.
The fecal score of piglets until 28 days of nursery was not affected (P>0.05) by the use of different growth promoters or their combinations in the diet of piglets or sows(Table 6).According to Taras et al. (2006), while studies with pigs and poultry have shown that probiotics have a positive effect on the feces, many of them show only a slight improvement in weight gain and feed conversion.According to these authors, the challenge may not be high enough to show the benefit of the use of probiotics on this factor.In this case, the diarrhea would occur due to less pathogenic microorganisms that cause self-limiting infections.Taras et al. (2007) found that probiotics led to a significant reduction in the incidence of diarrhea after weaning compared with the control group, regardless of the application form, the concentration in the diet and when you start treatment.These results indicate that probiotics may somehow contribute to the health of pigs, but if used as part of a broad concept by integrating management factors and other additives, as described above.Scharek et al. (2007a, b) found that supplementation with probiotics in the diet of mothers and piglets  demonstrated a positive effect on the intestinal immune system of piglets at weaning (28 days) and during the nursery phase.Moreover, the prevalence of Escherichia coli associated with pathogenic groups was lower with the use of probiotics, indicating better health status of pigs in this study.
In general, probiotics that contain different strains of bacteria appear to be effective since they increase the possibility of predominance of one or more strain in different situations (Walsh et al., 2008) and they may be used to reduce post-weaning diarrhea instead of antibiotics.However, other factors must also be considered for control of diarrhea after weaning, such as nutrition and environmental conditions to which animals are subjected.

Conclusions
The use of probiotics in the diet of sows in late gestation and during lactation, associated with the use of probiotics in the diet of piglets after weaning is effective in maintaining animal performance, the histo-physiological conditions of the gastrointestinal tract and the incidence of diarrhea during the nursery phase.

Table 2 -
Composition of the experimental diets

Table 4 -
Features of the jejunum of piglets receiving additives in the diet, from sows which also received antibiotics or probiotics during gestation and lactation

Table 5 -
Gastric and cecal pH of piglets receiving additives in the diet, from sows who received antibiotics or probiotics during gestation and lactation 1 Not significant at Chi-square (P>0.05)test.