Field Evaluation of a Bioregulator Containing Live Bacillus cereus Spores on Health Status and Performance of Sows and their Litters
Abstract
The efficacy of Paciflor, a bioregulator containing live Bacillus cereus CIP 5832 spores, was assessed in sows during late pregnancy and lactation, as well as in their piglets up to the growing phase. Two groups each of 30 pregnant gilts and sows received normal feed (T1 group), or feed with 85 g Paciflor per ton feed (T2 group), from 15 days prior to farrowing up to the end of the lactation period. Furthermore, 15 litters of the T1 group and 15 litters of the T2 group, were offered normal feed from the 5th to the 70th days of life (T1.1 and T2.1 groups, respectively), while the remaining 15 litters each of the T1 and T2 groups received the same feed but including Paciflor at a dose of 100 g/ton (from day 5 to day 49) and 50 g/ton (from day 50 to day 70). These pig litters were T1.2 and T2.2, respectively. No differences were seen between the T1 and T2 groups with respect to the clinical observations (loss of appetite, fever, mastitis, metritis and returns to oestrus, treatments applied, deaths, or removals to the slaughterhouse), gestation length, bodyweight of sows at farrowing or litter-size at birth. However, during lactation, the fat content of the dam’s milk was increased (0.46% more fat), the body weight loss of sows was reduced and the number of weaned pigs per sow was increased (0.6 more pigs per litter) after administration of Paciflor (P < 0.05). Weaning to service interval was also reduced by 1 day (P < 0.05). Moreover, piglets receiving Paciflor with their feed (T1.2 and T2.2 groups) showed less incidence of scours and lower mortality compared to the untreated piglets (T1.1 and T2.1 groups), particularly those pigs originating from Paciflor-treated dams (T2.2 group) (P < 0.05). Despite the fact that no difference was seen between groups with regard to the amount of feed consumed, the feed conversion ratio of Paciflor-treated piglets (T2.2 and T1.2) was significantly improved compared to that of the untreated piglets (T2.1 and T1.1) (P < 0.05). With respect to weight gain, for the Paciflor-treated piglets, those born to Paciflor-treated mothers (T2.2) were 0.56 kg heavier than those born to untreated dams (T1.2) (P < 0.05). It is concluded that administration of Paciflor in dams during the end of pregnancy and during lactation, as well as to their offspring during suckling and the flat-deck period is beneficial for the survival and growth of the piglets.
Introduction
The intestinal flora of a newborn starts to be established immediately after birth, and its balance is crucial for effective digestion and maximal absorption of nutrients, as well as for adequate body resistance against infectious diseases (Dufresne, 1998). Any stressor that may disturb the equilibrium of commensal micro-organisms within the gut will adversely affect the growth and health of the young animal. Despite the fact that a piglet is a separate individual, its viability up to the age of weaning greatly depends upon its mother in an indirect manner (colostrum and milk quantity and quality, diseases acquired by the dam, dam’s aggressive behaviour, etc.). It is therefore reasonable that mortality of the suckling pigs can further be reduced by improving the health and productivity of their mother during pregnancy and lactation.
To prevent or control both pre-weaning and post-weaning illnesses, antibiotics in the creep feed or grower’s ration have been used with good results (Kyriakis et al., 1994, 1995, 1996, 1997a, b). Furthermore, antibiotics incorporated into the feed of the pregnant sows, usually at a growth promoter dosage, appear to improve the viability of their progeny (Kyriakis et al., 1992a; Kantas et al., 1996, 1998). However, the recent demand for minimal use of antibiotics in the production of animal protein for human consumption challenges scientists to explore alternative ways, other than antibiotics, of preventing diseases.
Probiotics are live cultures of certain bacteria or yeasts, which potentially bioregulate the commensals’ equilibrium within the gut. Several studies have proved that these bioregulators have beneficial effect in the intestine and protect against Escherichia coli diarrhoea when administered orally to piglets (Alvarez et al., 1996; Breton and Munoz, 1998; Tournout et al., 1998; Kyriakis et al., 1999). However, the effect of probiotics on the health of the sow and gilt, and whether this effect extended to her offspring, was not well established.
This study was designed in order to assess the efficacy of Paciflor, a bioregulator containing live Bacillus cereus CIP 5832 spores, in sows during late pregnancy and lactation, as well as in their piglets up to the growing phase.
Materials and Methods
Description of bioregulator
Paciflor (Hoechst Roussel Vet GMBH, Wiesbaden, Germany) is a bioregulator containing live spores of the strain CIP 5832 of Bacillus cereus in a dry powder form (at least 1010 colony-forming units/g) which is incorporated in the feed. In this study, Paciflor powder was mixed in the feed meals.
Trial farm
This trial study was conducted in a farrow-to-finish pig farm with a capacity of 350 sows and an annual production of 6500 slaughter pigs. The farm had its own feed-mill. The piglets on the farm were weaned in weekly batches of approximately 130 ± 20 animals, each at the age of 25 ± 3 days. On flat decks, pigs were separated in pens of 10 animals each and remained there until the age of 10 weeks. After that age, the animals were moved to the fattening unit, where they remained until slaughter at the age of 23–24 weeks (body weight of 95–100 kg).
Gilts on the farm were served during their second oestrus. Each sow or gilt was twice served by the same boar, 12 and 24 h after oestrus detection. The whole breeding population was vaccinated against Aujeszky’s disease virus (ADV), swine influenza virus (SIV), parvovirus, atrophic rhinitis-causing bacteria and toxins, Escherichia coli, Clostridium perfringens and Erysipelothrix rhusiopathiae. For the control of endo/ectoparasites, all adults were treated with ivermectin twice a year. Virginiamycin had been routinely used in the sows’ diets according to previous studies (Kantas et al., 1998; Alexopoulos et al., 1998), but some time before the start of this trial this growth promoter was withdrawn because of its exclusion from the EC market. Soon after this withdrawal, an increased mortality rate occurred on the farm amongst the suckling piglets, due to mastitis-metritis-agalactica (MMA) syndrome, which had been moderately controlled by the virginiamycin. So at the time of the trial an increased mortality rate of suckling piglets was present.
Experimental design
Sixty Large White × Landrace pregnant gilts and sows, divided in two groups of 30 animals each, were used for the experiment. The first group of dams, designated T1, received normal feed with no antibiotics or growth promoters from the day of entering the farrowing house (15 days prior to farrowing) up to the end of the lactation period (28 days after farrowing). The other group of sows/gilts, designated T2, was fed during the same period with the same feed as T1, but Paciflor was mixed in with the feed at an inclusion level of 85 g Paciflor per ton of feed. Furthermore, 15 litters of the T1 group and 15 litters of the T2 group, were offered normal feed with no antibiotics or growth promoters from the 5th day after their birth up to the 10th week of age (designated T1.1 and T2.1, respectively), while the remaining 15 litters of each of the T1 and T2 groups received the same feed as the piglets of the T1.1 and T2.1 groups, but with 100 g Paciflor per ton of feed (from day 5 to day 49) and 50 g Paciflor per ton of feed (from day 50 to day 70) added. These pig litters were designated T1.2 and T2.2, respectively.
Feeds were meals prepared using local ingredients from the feed mill on site. Sows were fed a lactation feed as follows: from 15 days prior to the expected farrowing day up to 5 days prior to farrowing 3.5 kg of feed/sow/day and then the quantity was gradually decreased by 0.5 kg/sow/day up to the day of farrowing, when no feed was given to the sow. The feed allowance during the first 5 days of the lactation was gradually increased to the maximum of 2 kg plus 0.5 kg per suckling piglet/sow/day, which was maintained until weaning. Specification of the sow feed (on an air-dry basis) was the following: digestible energy 14.2 MJ/kg, crude protein 17%, fibre 5.4%, lysine 1%, calcium 0.95% and total phosphorus 0.82%. The piglets from the 5th to the 49th day after farrowing were offered a creep feed ad libitum and from day 50 to day 70 a weaner feed without added antibiotics and/or antibacterials was given. Specifications of the piglet feeds (on an air-dry basis) were the following: for the Creep feed: digestible energy 15 MJ/kg, crude protein 22%, fibre 2.2%, lysine 1.5%, calcium 1% and total phosphorus 0.8%; and for the weaner feed: digestible energy 14.2 MJ/kg, crude protein 19–20%, fibre 3.5%, lysine 1.4%, calcium 0.8% and total phosphorus 0.7%.
The trial was performed in six sequential weekly batches of dams and their piglets (five replicates). Sows/gilts were allocated to the groups considering: their bodyweight at their previous service (the average bodyweights of the group were not to differ), and their parity [so that dams of different parities (i.e. gilts, parity 1 or 2, parity 3 or 4, parity 5 or 6, parity 7 or more) were equally represented in each of the T1 and T2 groups]. Litters of sows and gilts within the same experimental group were equalized to 10 piglets/dam during the 3rd day after farrowing by adding or removing one or two piglets, but no more. Thus, each of the four groups of piglets was formed by 150 pigs.
Observations and sampling
The dams and their pigs were observed daily for clinical signs throughout the trial period. Dams were weighed at various times (at service prior to farrowing, at farrowing, at weaning, at postweaning service) and the number of pigs born and weaned, the length of gestation and the weaning to service interval were recorded. The milk of all sows was sampled at the 3rd and 15th days of lactation in order to measure its fat content according to procedures recommended by the Association of Official Analytical Chemists (1990).
Piglets were individually weighed at day 0 (day of birth), day 49 and day 70. Consumption of feed was recorded weekly per pen and the average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR) of the piglets were calculated. Diarrhoea was evaluated on pen basis using the following formula: Pen diarrhoea score=[(Pig1 × days of scouring) + … + (Pig10 × days of scouring)]/(70 days).
During the trial, pooled samples of each batch of sow and piglet feed were collected from the farm mill and sent to Hoechst Roussel Vet in order to assess the quality and to confirm the proper spore content of the feed.
Statistical evaluation
Each recorded parameter per experimental group was subjected to one-way analysis of variance using the General Linear Models (GLM) procedure of the SAS system (Version 6.12 for Windows 1996; Site No: 84912001/SAS Institute Inc. Cary, NY 27513, USA). Duncan’s multiple range test was used to compare means and Pearson’s χ2 test to compare percentages.
Results
As presented in Table 1, clinical observations of sows did not reveal any differences between groups T1 and T2 (P > 0.05). Loss of appetite, fever, mastitis, metritis and returns to oestrus were seen to a similar degree in both T1 and T2 dams, and in several cases, treatments were applied. However, a tendency for improvement was detected in the dams of T2 compared to the T1 group with regard to loss of appetite (P=0.06), pyrexia (P=0.08) and mastitis (P=0.09). No deaths of sows were seen and no removals to the slaughter house were necessary in any of the sow groups.
Administration of Paciflor in the last 15 days of gestation did not affect gestation length, bodyweight of sows at farrowing or litter-size at birth (Table 2). However, several positive effects were observed in dams when Paciflor’s administration was extended up to weaning. Thus, during lactation, the fat content of the dam’s milk was increased (0.46% more fat), the loss of bodyweight of the sows was reduced by 2.3 kg and the number of weaned pigs per sow was increased (0.6 more pigs per litter) (P < 0.05). Weaning to service interval was reduced by 1 day, while no effect was seen in sow bodyweight at time of service (Table 2) (P < 0.05).
Several of the piglets from the groups not receiving Paciflor with their feed (T1.1 and T2.1 groups), developed yellow watery diarrhoea, mainly during the first 4 weeks of their life. Diarrhoea scores from birth up to the end of the experiment, e.g. 70 days of age, were 0.079 ± 0.019 and 0.075 ± 0.022 for the T1.1 and T2.1 groups, respectively. Significantly less scours were seen in the two Paciflor-treated groups of piglets (T1.2 and T2.2 groups), which were scored 0.019 ± 0.009 and 0.016 ± 0.009, respectively, for the same period (P < 0.05).
As presented in Table 3, mortality in all groups of piglets during the first 3 days of life was between 3.26% and 7.22% with no differentiation amongst the groups. After the equalization of the litters to 10 pigs per dam, the overall mortality from day 4 to day 70 was high for the non-medicated litters (T1.1 and T2.1) when compared to the Paciflor-medicated piglets (T1.2 and T2.2). In particular, the mortality of the dam-medicated–piglet-medicated group (T2.2 group) was significantly lower than that of all the other groups (P < 0.05). Further analysis to the component stages showed that the reduction of mortality in Paciflor-treated piglets was marked throughout the high-risk suckling period (P < 0.05). The majority of deaths during this period (92%) was due to wasting because of diarrhoea.
As shown in Table 4, by the end of the measurements, the piglets that had received Paciflor performed significantly better with respect to bodyweight, ADG and FCR, compared to those that consumed untreated feed (P < 0.05). Paciflor-treated piglets born to Paciflor-treated mothers (T2.2) were 0.56 kg heavier than those born to untreated dams (T1.2). Of the untreated piglets, those born to Paciflor-treated mothers (T2.1) were 0.57 kg heavier than those born to untreated dams (T1.1), but they were still 0.56 kg lighter than the piglets of the T1.2 group (P < 0.05). Despite the fact that no difference was seen between groups with regard to the amount of feed consumed, the FCR of Paciflor-treated piglets (T2.2 and T1.2) was significantly improved compared to that of untreated piglets (T2.1 and T1.1) (P < 0.05).
Discussion
Piglets are born with sterile digestive tracts which are colonized by an indigenous microflora (lactobacilli, bacteroid and fusiform bacteria, clostridia, enterococci, enterobacteria, etc.). Some of these micro-organisms, which are potentially harmful (e.g. Escherichia coli), remain at constant numbers as long as antagonistic lactobacilli or enterococci grow in the gut. Disturbance of this equilibrium favours overgrowth of the pathogenic bacteria, causing enteric disease. Killing or inhibiting the growth of the pathogenic bacteria, and not only by the administration of antibiotics, is a way of treating an infectious diarrhoea. However, in terms of prevention, the concept of administering live micro-organisms which act antagonistically to the harmful bacteria appears to be better. The exact way in which these antagonistic bioregulators (probiotics) act is not fully understood. They may produce compounds such as lactic acid, which are inhibitory to the growth of other pathogens (Havenaar et al., 1992; Vandevoorde et al., 1992), or they may compete with other pathogens for nutrients (Freter, 1992; Raibaud, 1992), or for attachment sites (Pollmann et al., 1980; Pedersen and Tannock, 1989; Fuller, 1992; Johnson and Conway, 1992; Stewart et al., 1993). It was also suggested that piglets receiving probiotics appear to have more advanced systemic and local immunity, so these bioregulators may exert some role by improving immunological mechanisms (Lessard and Brisson, 1987; Perdigon et al., 1990; Rodriguez-Ropon et al., 1998).
The present study, was designed in order to see the effect of a bioregulator containing Bacillus cereus spores on the health of the sow and gilt, and whether this effect could extend to her offspring. The results have clearly shown that Paciflor had positive effects in both the mother and the piglet. In dams, the beneficial effect of the bioregulator was seen only during lactation and it was apparent as a reduction in the loss of sows’ bodyweight and a shortening of the weaning to service interval, both important parameters of female productivity. Although the action of probiotics in adult animals has not been well studied, a possible explanation could be that the microflora balance in the gut of these animals is optimized – as is the case in young animals – and a better utilization of nutrients is taking place, improving the body condition of the sow. Additionally, the shortening of the weaning to service interval, observed in the group administered bioregulator, could be attributed to the improvement of the body condition of the sow at weaning, since it is well established that there is a high correlation between body condition of the sow at weaning and the weaning to oestrus interval (Dial et al., 1992).
In piglets, Paciflor had both a direct and an indirect positive effect in both component periods. The direct effect arose from the treated feed consumed by the piglet with the consequence being the optimization of the commensals within the gut. This optimization was apparent by the reduction of the incidence of scours and mortality in the T1.2 group of pigs compared to the T1.1 group. The difference of 1.13 kg between the bodyweight of the pigs in the T1.2 and T1.1 groups represented the ‘clear’ direct effect of Paciflor on the piglets. Such a direct benefit of probiotics has been well documented by several studies (Alvarez et al., 1996; Breton and Munoz, 1998; Tournout et al., 1998; Kyriakis et al., 1999).
A smaller indirect effect of Paciflor for the piglet arising from the mother was also documented in the present trial. This effect was measured as equal to the 0.57 kg of piglet bodyweight at the age of 10 weeks (e.g. the difference between the T2.1 and T1.1 groups). The milk of the Paciflor-treated sows contained more fat than that of untreated sows and for this reason may be of higher nutritional value. The increased fat content of the milk was possibly due to the optimization of microbial digestion within the gut, a mechanism similar to that applying for ruminants, e.g. the appropriate ingestion of roughage has a positive effect on fat content of the milk. Previous studies have also shown that the consumption of dam’s milk of high fat content by piglets has a beneficial effect in their growth (Haydon and Hale, 1988; Kyriakis et al., 1992b). Sows fed with Paciflor are also likely to excrete faeces representative of their gut microflora, e.g. fewer pathogenic germs and high numbers of Bacillus spores. These faeces are spread in the farrowing pen and create a better (or even helpful) environment for the newborn pig, for colonization of the sterile gut in advance of delivery and before the consumption of creep feed. A third way in which a piglet can indirectly profit from its mother is by consuming her medicated food, but this appears not to be as important as the other two routes.
In general, the mortality rate of suckling piglets in the trial farm was high, as can be seen from the figures in the control groups. This can be attributed to a high prevalence of MMA syndrome, occurring on the farm at the time of the trial, as a consequence of the withdrawal of virginiamycin from the sows’ diet, because of its previous exclusion from the market. MMA syndrome and consequently piglet mortality had been reasonably controlled by the use of virginiamycin, as also shown in previous studies (Kantas et al., 1998; Alexopoulos et al., 1998). Data from this trial further demonstrated that administration of the bioregulator Paciflor in the sow’s diet had a tendency to reduce some symptoms of MMA, such as loss of appetite, pyrexia and mastitis, while it had a beneficial effect by reducing diarrhoea and subsequent mortality in suckling piglets. Further investigations are needed to clarify in which way a bioregulator has such beneficial results in sows and their litters.
Nevertheless, according to these results, piglets profit more from their feed than from their mother and this is obvious from the diarrhoea and mortality results, as well as from performance parameters (group T1.2 performed better than T2.1). The benefits from bioregulator are additive and both sources can be used by the piglet, as can be seen from the performances and health data of the T2.2 group, which were the best of all.
