P. A. Thacker

Alternatives to antibiotics as growth promoters for use in swine production: a review

In the past two decades, an intensive amount of research has been focused on the development of alternatives to antibiotics to maintain swine health and performance. The most widely researched alternatives include probiotics, prebiotics, acidifiers, plant extracts and neutraceuticals such as copper and zinc. Since these additives have been more than adequately covered in previous reviews, the focus of this review will be on less traditional alternatives. The potential of antimicrobial peptides, clay minerals, egg yolk antibodies, essential oils, eucalyptus oil-medium chain fatty acids, rare earth elements and recombinant enzymes are discussed. Based on a thorough review of the literature, it is evident that a long and growing list of compounds exist which have been tested for their ability to replace antibiotics as feed additives in diets fed to swine. Unfortunately, the vast majority of these compounds produce inconsistent results and rarely equal antibiotics in their effectiveness. Therefore, it would appear that research is still needed in this area and that the perfect alternative to antibiotics does not yet exist.

Effects of dietary threonine on performance, plasma parameters and immune function of growing pigs

Sixty-four growing pigs (Beijing Black Landrace Duroc), weighing an average of 17.5 ± 0.5 kg, were divided into four groups with four pens per treatment (two gilts and two castrates per per) and fed diets containing various levels of threonine to determine its effects on performance, plasma levels of free amino acids, plasma urea nitrogen and immune function during a 4 week trial. The basal diet was based on maize and soybean meal, supplemented with rapeseed meal and cottonseed meal, and contained 9.2 g kg 1 lysine and 5.9 g kg -1 threonine. L-threonine was added to the basal diet to provide 6.8, 7.7 and 8.9 g kg -1 threonine in the remaining three diets. On day 7, all pigs were injected with either Bovine Serum Albumin (BSA) or Swine Fever Attenuated Vaccine (SFAV) to determine humoral antibody response. The addition of threonine improved weight gain with the quadratic and cubic polynomial contrasts being significant (p < 0.05). Feed conversion was also significantly improved with the linear, quadratic and cubic polynomial contrasts being significant (p < 0.01). The highest weight gain occurred at 6.8 g kg - threonine and the best feed conversion at 8.9 g kg - threonine. The concentration of plasma urea nitrogen decreased (p < 0.01) and reached a plateau when dietary threonine increased from 5.9 to 6.8 g kg - 1 . Serum threonine increased (p < 0.01) and serum lysine decreased (p < 0.01) as dietary threonine increased, with both amino acids showing sharp inflection points at 6.8 g kg -1 dietary threonine. Increasing dietary threonine levels increased serum IgG concentration (p < 0.01) and anti-BSA antibody (p < 0.01) level. In conclusion, although maximum growth rate of 17-31 kg pigs occurred at a dietary threonine level of 6.8 g kg 1 , higher threonine levels were needed to maximize humoral antibody production and IgG levels.

Effects of the antimicrobial peptide cecropin AD on performance and intestinal health in weaned piglets challenged with Escherichia coli.

This study was conducted to determine the effects of the antimicrobial peptide cecropin on performance and intestinal health in piglets. Newly weaned barrows were randomly assigned to one of three treatments (n=8), including a corn-soybean basal diet or similar diets supplemented with antibiotics (100 mg/kg kitasamycin plus 800 mg/kg colistin sulfate) or 400 mg/kg cecropin AD. On day 13, all piglets were orally challenged with 10(9)CFU/mL of Escherichia coli K88. On day 19, all piglets were euthanized and sampled. Before challenge, piglets fed antibiotics had greater weight gain, feed efficiency, nitrogen and energy retention than the control (P<0.05). E. coli challenge decreased weight gain, feed intake and feed efficiency for the control piglets (P<0.05) but not for the antibiotic or cecropin AD treated piglets. The incidence of diarrhea post-challenge in the antibiotic and cecropin AD treatments decreased compared with the control piglets. The total viable counts of cecal E. coli were lower while the Lactobacilli counts were higher in the antibiotic and cecropin AD treatments compared with the control (P<0.05). Cecropin AD treatment decreased total aerobes while increasing total anaerobes in the ileum (P<0.05). A higher villus height to crypt depth ratio in the jejunum and ileum as well as a deeper crypt depth in the jejunum and higher villus height in the ileum were observed in piglets fed antibiotics or cecropin AD compared with control piglets (P<0.05). Piglets fed the control diet had lower levels of secretory IgA in their jejunum and lower serum IgA, IgG, interleukin-1β and interleukin-6 compared with the other treatments (P<0.05). Overall, these data suggest that cecropin AD enhances pig performance through increasing immune status and nitrogen and energy retention as well as reducing intestinal pathogens in weaned piglets.

Chito-oligosaccharide reduces diarrhea incidence and attenuates the immune response of weaned pigs challenged with Escherichia coli K88.

Seventy-two barrows (Landrace × Large White, initial BW of 4.9 ± 0.3 kg and 17 ± 3 d old) were used to determine if dietary chito-oligosaccharides can replace antibiotics as a means to reduce signs associated with infection in weaned pigs challenged with Escherichia coli. Pigs were assigned to 1 of 4 treatments in a randomized complete block design using 6 pens per treatment with 3 pigs per pen. The treatments consisted of pigs fed the unsupplemented corn-soybean meal diet challenged or unchallenged with E. coli K88 and pigs fed the same diet supplemented with 160 mg of chito-oligosaccharides or 100 mg of cyadox/kg and challenged with E. coli K88. On d 7, 1 group of pigs fed the unsupplemented diet, as well as all pigs fed diets containing chito-oligosaccharides or cyadox, were orally dosed with 30 mL of an alkaline broth containing E. coli K88. Another group of pigs fed the unsupplemented diet was orally dosed with 30 mL of sterilized alkaline broth. Fecal consistency was visually assessed each morning from d 7 to 14. Blood samples were collected at 0, 24, 48, and 168 h postinfection. On d 14 postchallenge, all pigs were killed to evaluate intestinal morphology and determine E. coli concentrations in the intestine. During the postchallenge period (wk 2), unsupplemented pigs challenged with E. coli had decreased (P < 0.05) BW gain, feed intake, fecal consistency, villus height, villus height:crypt depth ratio, and plasma IGF-1, and increased (P < 0.05) diarrhea incidence, E. coli counts in the intestine, plasma interleukin-1β, plasma IL-10, and IGA-positive cells in the jejunal and ileal lamina propria, compared with unchallenged pigs. Supplementation with cyadox largely mitigated these effects. Although chito-oligosaccharide reduced the incidence of diarrhea, the growth performance of E. coli-challenged pigs supplemented with chito-oligosaccharide was not better than that of unsupplemented pigs challenged with E. coli. Therefore, chito-oligosaccharide, at the amount used in this experiment, does not seem to be an effective substitute for antibiotics as a growth promoter for newly weaned pigs challenged with E. coli.

Effects of stachyose on performance, diarrhoea incidence and intestinal bacteria in weanling pigs.

A three-week trial was conducted to evaluate the effects of the oligosaccharide stachyose on performance, diarrhoea incidence and intestinal bacterial populations in weaned pigs (7.96±0.2kg). A total of 144 crossbred (Landrace × Large White × Duroc) pigs weaned at 28 days were allotted to one of four treatments with six pens per treatment and six pigs per pen. The experimental diets were based on maize, dried whey and whole-fat milk and were supplemented with 0, 1 or 2% stachyose. A fourth diet contained no milk but instead contained 20% soybean meal to provide 0.78% stachyose and 0.21% raffinose. Inclusion of 1 or 2% stachyose in the diet depressed growth compared with pigs fed the control diet. Pigs fed the soybean meal diet gained weight at a rate similar to pigs fed the diet containing 1% added stachyose. Diarrhoea incidence was highest for pigs fed the soybean meal diet and lowest for pigs fed the control diet, with pigs fed the diets containing stachyose being intermediate. Pigs fed 1% stachyose had more lactobacilli in the ileum as well as more bifidobacteria in the caecum and colon than control pigs. They also had fewer enterobacteria in the colon. In contrast, pigs fed the diet containing 2% stachyose had fewer lactobacilli and bifidobacteria in the jejunum, ileum and caecum than did control pigs. Volatile fatty acids in the ileum, caecum and colon were highest for pigs fed 1% stachyose and lowest for pigs fed 2% stachyose. Volatile fatty acid concentrations were not significantly different between pigs fed the soybean meal diet and those fed the control. The overall results of this experiment indicate that the oligosaccharide stachyose had a negative effect on pig performance and its presence may partially explain the poorer performance observed when soybean meal is used as the sole source of supplemental protein in cereal-based diets fed to weaned pigs.

Molecular Structure and Metabolic Characteristics of the Proteins and Energy in Triticale Grains and Dried Distillers Grains with Solubles for Dairy Cattle

To our knowledge, there is no research on the molecular structure of triticale grain in comparison with other types of cereal grains and metabolic characteristics of the protein and energy in this grain and its coproducts, called dried distillers grains with solubles (DDGS), for dairy cattle. The objective of this study was to identify differences in molecular structures of proteins among grains and their DDGS using a molecular spectroscopy technique, namely, DRIFT, and to determine the nutrient profile and supply to dairy cattle. The protein molecular structure studies showed a difference (P < 0.01) in the amide I to amide II ratio and the α-helix to β-sheet ratio between grains and their DDGS. The energy content was similar for triticale grain and DDGS. There were differences in the protein and carbohydrate subfractions (P < 0.05) and the ruminal degradability of DM, CP, and NDF (P < 0.01) between triticale grain and DDGS. Triticale grain and DDGS had similar intestinal digestibility of rumen undegraded CP. However, triticale DDGS had higher (P < 0.01) predicted total metabolizable protein and degraded protein balance than triticale, indicating that triticale DDGS is a superior protein source for dairy cattle as compared with triticale grain. Bioethanol processing induced changes in the protein molecular structure.

Effects of expeller pressed camelina meal and/or canola meal on digestibility, performance and fatty acid composition of broiler chickens fed wheat–soybean meal-based diets

This experiment was conducted to compare the effects of graded levels of camelina meal and/or canola meal on digestibility, performance and fatty acid composition of broiler chickens. A total of 180-day-old male broiler chicks were randomly assigned to one of the six treatments. The control diet was based on wheat and soybean meal and contained 15% canola meal. The experimental diets contained 3%, 6%, 9%, 12% or 15% camelina meal added at the expense of canola meal. Chromic oxide (0.35%) was added to all diets as a digestibility marker. On the morning of day 22, birds were killed by cervical dislocation and their abdominal fat pad was obtained. The apparent total tract digestibility of dry matter and energy as well as nitrogen retention all declined linearly (p < 0.01) with increasing levels of dietary camelina meal. Weight gain (p < 0.01) and feed intake (p = 0.08) were linearly reduced as the level of camelina meal in the diet increased. Feed conversion ratio was also negatively affected by camelina meal (p < 0.01). Birds fed diets containing 15% camelina meal had significantly higher (p < 0.01) levels of polyunsaturated fatty acids, total n-3 fatty acids, total n-6 fatty acids and a significantly lower ratio of n-6 to n-3 fatty acids (p < 0.01) than birds fed canola meal. In conclusion, the inclusion of camelina meal in their diet significantly reduced the growth and feed conversion ratio of broilers compared with canola meal. However, the potential to incorporate n-3 fatty acids into carcass tissues may provide some justification for including camelina meal in poultry rations.

The influence of growth hormone injections on the endocrine and metabolic status of gilts

Twelve Yorkshire x Landrace prepubertal gilts were assigned equally to treatments involving daily injections of either porcine growth hormone (GH, 90 micrograms/kg) or vehicle buffer from 150 to 159 d of age. Blood samples were obtained every hour from 0600 hr at 153 d until 0500 hr at 154 d of age, inclusively. At 0800 hr on 154 d, gilts received an injection of 500 IU PMSG, followed 96 hr later by 250 IU hCG. Gilts were slaughtered at 163 d and the ovaries recovered for an assessment of the ovarian response to the gonadotrophic stimulation. Five control gilts (83%) exhibited a normal ovulatory response but only one GH gilt (17%) was so designated (P less than 0.05). There was no apparent effect of treatment on serum concentrations of LH, FSH or cortisol. Growth hormone treatment reduced serum concentrations of T4 (P less than 0.001) and prolactin (P less than 0.02), but increased serum GH (P less than 0.001), T3 (P less than 0.06), insulin (P less than 0.001) and glucose (P less than 0.001). Serum concentrations of free fatty acids (FFA) were not significantly altered by exogenous GH. The concomitant elevation of serum insulin and glucose suggests that an insulin-resistant state was induced which, if evident at the ovarian level, may be a factor mediating the adverse effects of exogenous GH on ovarian function. The data presented also suggests that circulating concentrations of thyroid originating hormones are altered by exogenous GH.

Aj-rel and Aj-p105, two evolutionary conserved NF-κB homologues in sea cucumber (Apostichopus japonicus) and their involvement in LPS induced immunity.

The nuclear factor κB (NF-κB) has been evolutionary conserved from insects to mammals and plays a major regulatory role in the initiation of physiological responses. In this study, we identified and characterized a primitive and functional NF-κB pathway active in the immune defence of the sea cucumber (Apostichopus japonicus). The ancient NF-κB homologues, Aj-rel and Aj-p105, share numerous signature motifs with their vertebrate orthologues, notably the Rel Homology Domain, Rel Protein Signature DNA Binding Motif, Nuclear Localization Signal and the Ankyrin Repeats for Aj-p105. Phylogenetic analyses indicate that these homologues belong to class I and II of NF-κB respectively. We examined the dimerization of Aj-rel and Aj-p105 and our results demonstrated that Aj-rel forms heterdimers with Aj-p105 and the degradation product of Aj-p105, namely Aj-p50. We further observed that LPS stimulation led to the degradation of Aj-p105 and the nuclear translocation of Aj-rel and Aj-p50. Taken together, our data indicate that the NF-κB signaling cascade is active in sea cucumber and plays a crucial role in regulating their immune defence. Our results increase the available information on sea cucumber immunity and provide new information for use in the study of the comparative and evolutionary aspects of immunity.

Composition and nutritive value of acidulated fatty acids, degummed canola oils and tallow as energy sources for starting broiler chicks

Abstract Two experiments were conducted to determine the nutritive value of various lipid sources when fed to starting broiler chicks. In Experiment 1, two replicates of 96 and 144 1-day-old, male broiler chicks were fed diets supplemented with 80 g kg−1 of either tallow, acidulated fatty acid (AFA), water degummed canola oil or super degummed canola oil. Each diet was fed ad libitum to ten pens of six birds. In Experiment 2, 72 1-day-old broiler chicks were fed diets supplemented with 80 g kg−1 of either tallow or AFA or a combination of 80 g kg−1 AFA and 10 g kg−1 glycerol. Each diet was fed ad libitum to four pens of birds with three males and three females per pen. All diets (meal form) were based on wheat and soya-bean meal and contained chromic oxide (5 g kg−1) as a digestibility marker (Table 1). Chicks were weighed individually at the start of the experiment and at weekly intervals thereafter for the duration of the 3 week feeding trials. Feed consumption was determined on a pen basis at the time of the weekly weighing. During the third week of each experiment, samples of droppings were collected in order to measure nutrient retention. In Experiment 1, birds fed the diets supplemented with either the water degummed or the super degummed canola oil gained faster (P feed gain ratio (P feed gain ratio, liver and heart weight, serum cholesterol or nutrient retention as a result of treatment. Fat source had a significant (P