Relationship between residual feed intake and radiated heat loss using infrared thermography in young beef bulls

Residual feed intake (RFI) has been used to select metabolically efficient cattle in beef breeding programs, particularly for sire selection. Adoption of genetic selection using RFI has been limited due to the cost and difficulty of measuring individual feed intake. An alternative method of predicting RFI is to measure radiated heat loss using infrared thermography (IRT) as previous studies have shown promise using this technique to predict metabolic efficiency in mature cows, heifers, and growing bulls. The objective of this study was to explore use of IRT to predict RFI in growing beef bulls. Sixty bulls in each of two years were fed either a forage-based or a grain-based ration. Eye (Ey) and cheek (Ck) surface temperatures were measured using infrared images of the head collected on 16 and 14 sample days in Years 1 and 2, respectively, using a FLIR S60 camera. In Year 2, infrared images were collected continuously using a within-pen FLIR A310 camera system. Bulls were grouped into low, medium and high classes based on ± 0.5 standard deviations of backfat adjusted residual feed intake (RFI_Fat); RFI_Fat values ranged from - 2.27 to + 2.61 kg DM day^-1 (mean=0.0; SD=0.61). Sample day Ey and Ck temperatures were pooled and an average temperature was calculated for individual bulls. Average Ey and Ck temperatures measured using the FLIR S60 and the within-pen camera did not differ significantly across low, medium and high RFI groups (P > 0.05). Temperature deviations associated with extremes in ambient temperature (placing animals outside their thermoneutral zone) or underlying subclinical health problems could bias results in IRT measurements and RFI ranking. Standardization of IRT data and the conditions during measurement is necessary to more accurately assess its potential use to predict RFI.

Effect of yeast-derived products and distillers dried grains with solubles (DDGS) on antibody-mediated immune response and gene expression of pattern recognition receptors and cytokines in broiler chickens immunized with T-cell dependent antigens

This study evaluated the effect of yeast-derived products on innate and antibody mediated immune response in broiler chickens following immunization with sheep red blood cells (SRBC) and bovine serum albumin (BSA). One-day-old male broiler chickens (Ross-308) were randomly assigned to 6 dietary treatments of 9 replicate cages of 5 birds each per treatment. Dietary treatments consisted of a Control diet without antibiotic, and diets containing 11 mg/kg of virginiamycin, 0.25% of yeast cell wall (YCW), 0.2% of a commercial product Maxi-Gen Plus containing processed yeast and nucleotides, 0.05% of nucleotides, or a diet containing 10% of DDGS. On days 21 and 28 post-hatching, 5 birds per treatment were immunized intramuscularly with both SRBC and BSA. One week after each immunization, blood samples were collected. Serum samples were analyzed by hemagglutination test for antibody response to SRBC, and by ELISA for serum IgM and IgG response to BSA. On d 35, 5 birds per treatment were euthanized and the tissue samples from the cecal tonsils were collected to assess the gene expression of toll-like receptors TLR2b, TLR4, and TLR21, monocyte mannose receptor (MMR), and cytokines IL-10, IL-13, IL-4, IL-12p35, and IFN-γ. The results for gene expression analysis demonstrated that the diet supplemented with YCW increased the expression of TLR2b and T-helper type 2 cytokines IL-10, IL-4, and IL-13 relative to the Control; and the expression of TLR4 and IL-13 was upregulated in the nucleotide-containing diet. However, the diets containing antibiotics or Maxi-Gen Plus downregulated the expression of IFN-γ compared to the control. The primary antibody response to SRBC was not affected by diets. However, the diet containing YCW increased the secondary antibody response to SRBC compared to the antibiotic treatment. Neither primary nor secondary IgG and IgM response against BSA were affected by diets. In conclusion, supplementation of the diet with YCW stimulated Th2 cell-mediated immune response indicating the immunomodulatory activities of these products following immunization with non-inflammatory antigens.

Standardized ileal amino acid digestibility in wheat, barley, pea and flaxseed for broiler chickens

Bandegan A., Golian, A., Kiarie E., Payne R. L., Crow G. H., Guenter W. and Nyachoti C. M. 2011. Standardized ileal amino acid digestibility in wheat, barley, pea and flaxseed for broiler chickens. Can. J. Anim. Sci. 91: 103–111. Experiments were conducted to estimate ileal amino acids (AA) digestibility in six wheat (exp. 1; 288 birds), seven barley (exp. 2; 252 birds), five pea (exp. 3; 240 birds) and five flaxseed (exp. 4; 216 birds) samples in male Ross broiler chicks. Wheat, barley and pea were the sole source of dietary AA in exps. 1, 2 and 3, whereas, for exp. 4, flaxseed and wheat (50:50 wt/wt) or wheat provided dietary AA. Chromic oxide was the indigestible marker. Birds were fed chick starter for the first 14 d; on day 15 each test diet was randomly assigned to six cages, each with six (exps. 2 and 4) or eight (exps. 1 and 3) birds. On day 21, birds were killed and digesta were sampled to determine the apparent ileal AA digestibility (AID). The standardized ileal digestibility (SID) values were calculated using ileal endogenous AA losses previously determined in our laboratory from birds fed N-free diet. The mean SID values for indispensable AA ranged from 83.7% (Lys) to 93.8% (Phe), 80.4% (Arg) to 90.9% (Phe), 86.0% (Met+Cys) to 94.2% (Arg) and 47.4% (Thr) to 66.7% (Met) for wheat, barley, peas and flaxseed samples, respectively. Overall, SID AA estimates for flaxseed had higher (> 13%) coefficients of variation (CV) compared with other ingredients (CV<6%). These SID AA data will help nutritionists to formulate broiler diets that more closely match the birds' requirements and minimize nutrient excretion.

Morning vs. evening feed delivery for lactating dairy cows

Nikkhah, A., Furedi, C. J., Kennedy, A. D., Scott, S. L., Wittenberg, K. M. Crow, G. H. and Plaizier, J. C. 2011. Morning vs. evening feed delivery for lactating dairy cows. Can. J. Anim. Sci. 91: 113–122. A study was conducted to investigate the effects of changing feed delivery time from morning (0900) to evening (2100) on feed intake, diurnal feed intake patterns, digestion, rumen fermentation, milk production and composition, as well as on several blood metabolites. Eight (four ruminally cannulated) lactating Holstein cows, consisting of four primiparous and four multiparous cows, were used in the study. The change in the time of feed delivery increased the proportion of feed consumed within 3 h of feed delivery in all cows (54.7 vs. 46.3±4.1%, means±SE, P=0.05), but increased daily dry matter intake only in primiparous cows (18.5 vs. 20.4±0.7 kg d−1, P=0.05). Average daily concentrations of blood glucose, lactate, urea and β-hydroxybutyrate (BHBA) as well as rumen pH and concentrations of volatile fatty acids (VFA) were not affected by feed delivery time. However, rumen pH was lower (P<0.05), at 5 and 6 h after feed delivery, while total rumen VFA and acetate were higher (P<0.05) only at 6 h after feed delivery in cows fed in the evening. Also, compared with feed delivery at 0900, feeding cows at 2100 resulted in lower (P<0.05) blood glucose and urea at 2 h after feed delivery, and increased BHBA (P<0.05) at 4 and 6 h after feed delivery. Cows fed at 2100 tended to produce more milk fat than those fed at 0900 (1.11 vs. 0.97±0.07 kg d−1, P=0.08). Milk yield and milk protein were not affected by the time of feed delivery. Changing the feed delivery time from morning to evening increased apparent total tract digestibility of dry matter, nitrogen, and neutral detergent fibre. The results of this study suggest that changing time of feed delivery from 0900 to 2100 increases feed consumption within 3 h after this delivery and rumen fermentation within 6 h after this delivery, changes diurnal patterns of glucose, urea and BHBA in peripheral blood, tends to increase milk fat, and increases nutrient digestibilities.

Effects of Monensin and Stage of Lactation on Variation of Blood Metabolites Within Twenty-Four Hours in Dairy Cows

Effects of prepartum administration of a monensin controlled release capsule (CRC) and stage of lactation on variation of blood metabolites within 24 h were determined in 16 dairy cows. Cows were fed a total mixed ration ad libitum twice daily at 0700 and 1300 h. At calving, cows were switched from a close-up dry cow diet to a lactating cow diet. Cows were blood sampled every 3 h for 24 h at 3 stages of lactation, including 1 wk before calving (wk -1), 1 wk after calving (wk 1), and 6 wk after calving (wk 6). Serum concentrations of glucose, beta-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), and urea exhibited significant variation within 24 h. Glucose and NEFA were, respectively, 0.09 and 0.08 mM lower between 1030 and 2230 h than between 2230 and 1030 h. beta-Hydroxybutyrate and urea were, respectively, 95.1 and 0.49 mM higher between 1030 and 2230 h than between 2230 and 1030 h. Monensin did not significantly affect glucose, NEFA, and urea in this study. Monensin reduced BHBA at wk 1, but not at wk -1 or wk 6. Glucose was lower and BHBA and NEFA were higher at wk 1 compared with wk -1 and wk 6. Urea was higher at wk 6 compared with wk -1. The variation within 24 h of glucose, BHBA, and NEFA were not affected by monensin and stage of lactation. Diurnal variation of urea was affected by stage of lactation, but not by monensin.

Multiple trait estimates of genetic parameters for juvenile growth and calving traits in Canadian Angus cattle

Two analyses, both with three calf body weights at birth (BW), weaning (WW) and yearling (YW), one including first calving date (CD1) using a four-trait model, and the other including calving date (CD) and interval (CI) in a five-trait model, were carried out for a pooled population of beef cattle from one herd in Manitoba (n = 3,601), three herds in Alberta (n = 779, 600 and 967) and one herd in Saskatchewan (n = 495) totaling 6442 calving records for years 1984 through 2001.

Genetic association between cows’ stayability to three years of age and juvenile growth traits in Canadian Angus herds

Bivariate linear animal models were fit using MTDFREML programs for the analysis of cows’ stayability to 3 yr (STAY3, n = 1, 703) as a binary scored trait paired with body weights at birth (BW, n = 6,116), 205-d weaning (WW, n = 5,360,) and 1 yr of age (YW, n = 5250) in Angus cattle. For STAY3, the model included a fixed effect due to herd ×year of cow’s birth along with a random direct genetic effect. For each of BW, WW and YW, the model included fixed effects due to herd ×birth year, birth season, birth type, calf’s sex and the age of dam (as linear and quadratic covariates), while the random effects were direct and maternal genetic effects and permanent maternal environmental effects. Survival analysis revealed that the risk of cows, 10 yr or less in age, being culled from five Canadian Angus herds was highest between 2 and 3 yr of age. The direct heritability (h2) estimates for BW, WW and YW were 0.54, 0.73 and 0.47, respectively, and corresponding maternal heritability estimates were 0.14, 0.33 and 0.13, respectively. Furthermore, the direct h2 estimate for STAY3 from three bivariate analyses was 0.23–0.24. Estimates of direct-maternal genetic correlations of BW, WW and YW were -0.18, -0.70 and -0.39, respectively. The direct genetic correlations of STAY3 with BW, WW and YW were -0.15 to -0.09 indicating that selection for growth would have less detrimental influence on the stayability trait of cows. The correlations of direct genetic effects of STAY3 with maternal genetic effects of BW, WW and YW were between 0.20 and 0.25, indicating their favorable relationships as correlated traits. Key words: Stayability, growth traits, heritability, genetic correlations, beef cattle

Genetic diversity among Canadienne, Brown Swiss, Holstein and Jersey cattle based on mitochondrial D-loop sequence variation

Polymorphisms creating 36 unique haplotypes were observed with in breeds at 55 sites in the displacement loop (D-loop) region of the mitochondrial DNA (mtDNA) consisting of 814 bp. The majority (56%) of the differences observed were the result of nucleotide substitution events with 19 transitions, 12 transversions, 11 deletions, 12 insertions and 1 inversion. In all cases, the insertions and deletions were of a single nucleotide. Canadienne cattle were found to have 60% unique haplotypes within the population compared to 89% in Brown Swiss, 90% in Holstein and 100% in Jersey cattle, possibly reflecting the narrow genetic base in the Canadienne breed. The degree of sequence divergence in the D-loop region of mtDNA was based on samples from 20 Canadienne, 9 Brown Swiss, 10 Holstein and 10 Jersey cattle and a phylogenetic analysis showed that these cattle (Bos taurus) were not evolutionarily distinct. All four breeds grouped together when a strict consensus tree was generated. Intra-breed variability proved to be high for the Canadienne, Holstein and Jersey breeds (57–73%) but not the Brown Swiss breed (29%). The Canadienne and Brown Swiss (45%), and Brown Swiss and Holstein (43%) showed the lowest degree of inter-breed variability. The greatest variability among the four breeds was between Canadienne and Jersey (80%) cattle. These findings question the validity of phenotypic assessment of genetic diversity, such as Canadienne cattle being described as “Black Jersey”. Key words: Genetic distance, phylogenetic analysis, D-loop sequence, cattle

Feed intake, growth and carcass parameters of swine consuming diets containing low levels of deoxynivalenol from naturally contaminated barley

The ubiquitous nature of deoxynivalenol (DON) in the eastern prairie region of Canada necessitates the development of strategies to enhance the utilization of affected grains by swine producers. To this end, an experiment was designed to determined the impact of low levels of DON on feed intake and growth of swine. 144 Cotswold pigs (initial weight = 23.4 kg ± 0.3 SE) were assigned to receive diets containing either 0, 1 or 2 ppm DON in the final feed (four pens, each containing six barrows and six gilts, per treatment). The final DON contents of the diets were derived by diluting DON-contaminated barley (DON = 4.9 ppm) with DON-free barley. Diets were formulated to provide a minimum of 13.4 MJ kg-1 digestible energy (DE) and 0.81% total lysine, and the same diets were used throughout the grow-finish period. Feed intake (per pen basis; kg d-1), body weight gains (kg d-1) and feed conversion were measured on a weekly basis. Pigs were slaughtered at approximately 110 kg and indices of carcass merit collected. The presence of 2 ppm DON depressed feed intake by 7.6% (P < 0.05) relative to 0 ppm DON controls, with pigs consuming the 1 ppm DON diet having intermediate levels of feed depression. However there was no significant effect of DON on average daily gain or feed conversion at any stage of the experiment, The presence of DON in the diet increased the proportion of animals reaching 110 kg, estimated from individual regression curves, at times greater than the median value (169.5 d; chi-squared analysis P < 0.05), in gilts, but was without effect on barrows (median = 158.2 d). Measures of carcass weight, index, backfat thickness, and depth of lean over the loin were not affected (P > 0.05) by the presence of DON in the diet, irrespective of gender, however there was significant linear effect of DON (P < 0.05) on the loin premiums received, with higher values realized with increasing DON content in the diet. The current data provide evidence that grains containing DON could be used in the diets of barrows to provide 2 ppm in the final feed however, caution is required when considering their utilization for gilts. Key words: Deoxynivalenol, feed intake, performance, swine, barley, carcass merit

Genetic diversity among Canadienne, Brown Swiss, Holstein, and Jersey cattle of Canada based on 15 bovine microsatellite markers

The genetic diversity among Canadienne, Brown Swiss, Holstein, and Jersey cattle was estimated from relationships determined by genotyping 20 distantly related animals in each breed for 15 microsatellites located on separate chromosomes. The Canadienne, Holstein, and Jersey cattle had an average of six alleles per loci compared with five alleles for Brown Swiss. Furthermore, a number of potentially breed-specific alleles were identified. The allele size variance among breeds was similar, but varied considerably among loci. All of the loci studied were equally heterozygous, as were Brown Swiss, Canadienne, and Holstein cattle (0.68-0.69) whereas Jersey cattle showed lower heterozygosity (0.59). The within-breed estimates of genetic distance were greater than zero and significant. The genetic distance between Canadienne and Holstein (0.156), Brown Swiss (0.243), and Jersey (0.235) was negligible, suggesting close relationship. Concurrently, Brown Swiss and Holstein (0.211) cattle also demonstrated close relationship. In contrast, the Jersey breed was genetically distant from the Brown Swiss and Holstein cattle (0.427 and 0.320, respectively). The characterization of Canadienne cattle, as part of the genetic resource conservation effort currently underway in Canada, underscores the difficulty in scientifically establishing unique breeds. Therefore, the need to consider all relevant morphological characteristics and production performance in combination with available cultural, historical, pedigree, and molecular information becomes relevant when identifying breeds for conservation.

Transfer of omega-3 linolenic acid and linoleic acid to milk fat from flaxseed or Linola protected with formaldehyde

Four Holstein cows were randomly assigned to four treatments in a 4 × 4 Latin square design. The primary objective of this study was to measure the transfer and increased level of omega-3 fatty acid C18:3 in milk by feeding sup plemental protected fat from flax and, second, to measure the transfer and increase in level of C18:2 by feeding supplemental protected fat from linola. The four dietary treatments were total mixed rations (TMR) plus i) control-no added fat, ii) high levels of protected Linola containing high linoleic acid content, iii) low level of protected flax containing high linoleic acid content and iv) high levels of protected flax containing high linolenic acid content. Linola is a variety of Solin containing approximately 74% linoleic acid, which was developed from flax. These supplements were added to the diet as a top dress and provided 454 g fat (high level) from the protected Linola product, 187 g fat (low level) from the protected flax product and 410 g fat (high level) from the protected flax product. Treatments had no effect on feed intake, milk yield or milk content of fat, protein or solids not fat. Medium chain fatty acids, C12:0 to C16:0, were significantly lower (P < 0.05) in the milk of cows fed supplemental fat. Milk stearic acid (C18:0) was significantly greater in the milk fat from cows fed Linola vs. control, but was unaffected by other dietary treatments. Milk linoleic acid (C18:2) was significantly higher at 10.3% in the milk of cows fed the protected Linola vs. the control at 4.8%. Linolenic acid (C18:3) was not affected by feeding Linola, but was significantly greater in the milk of cows fed the high level of protected flax (6.4% vs. 0.8% in the control). This represents an eightfold increase, while the low level of protected flax diet increased C18:3 by 3.9-fold in milk fat. Supplementing dairy cow diets with a formaldehyde-treated flax product at acceptable levels of fat for high producing cows results in a milk fat high in omega-3-linolenic acid. Key words: Flaxseed, cow, milk, fatty acids, linoleic acid, linolenic acid

Development of a multipurpose feed enzyme analyzer to estimate and evaluate the profitability of using feed enzyme preparations for poultry

Previous studies have demonstrated that a log-linear equation could accurately predict chick performance when a feed enzyme was added to a diet and that the slope of the equation provided a measure of the efficacy of different enzymes. The objective of the study was to develop a software package, a Multipurpose Feed Enzyme Analyzer (MPFEA), based on an equation designed to evaluate the profitability of using feed enzymes. A high correlation between the efficacy of different feed enzymes (B values, the slopes of the equations) and the maximal profits was obtained when feed enzymes were added to a barley-based diet (r2 = 0.99, P < 0.0005). In contrast, there was a low correlation between the B values and the maximal profits when a feed enzyme was added to different cereal-based diets (r2 = 0.61, P = 0.2171). It appeared that there is not always a close association between efficacy of an enzyme when added to different cereal-based diets and the corresponding profitability. The MPFEA was highly versatile, as any combination of inputs such as the amounts of a feed enzyme and a substituted cereal required to yield a profit level could be determined. In conclusion, the MPFEA can accurately evaluate profitability of using different feed enzymes; select the most profitable cereal for a given feed enzyme; determine the optimal amounts of a feed enzyme, a cereal, or both; and even estimate the alternate price for a feed enzyme and a cereal. It should provide a useful tool for nutritionists.

Electronic monitoring of mounting behavior in beef cattle on pasture

An automated heatmount detection system was employed to detect estrus for artificial insemination in 57 beef cows. First service conception rate was 84.2% and the pregnancy rate was 89.5% for a 42-day breeding season. Duration of estrus was 9.6 h, sx = 0.5 h and mounting activity was lowest during the dark part of the day.

Effect of fungal biomass in alfalfa hay on intake and total tract digestion in growing beef calves

Two experiments were conducted to determine effects of fungal biomass (FB), as determined by glucosamine analysis, in alfalfa hay on intake and total tract digestion when fed to growing beef calves. Mycotoxins were not detected in hays used for these experiments. A feedlot trial using 40 weaned Angus calves (270.2 +/- 9.7 kg) showed that DM intake was not affected (P > .05) by FB content of the hay diets. No adaptation response was observed when animals with no previous exposure to molded feed were introduced to hay containing various levels of FB. Hematocrit and plasma cortisol levels were not affected (P > .05) by the presence of FB in the hay. Eight steers were used, in two 4 x 4 Latin squares, for intake and total tract digestibility determinations of two alfalfa hays having similar nutrient profiles but differ in FB concentrations. Hays were fed in long or chopped form. Level of FB did not affect (P > .05) DM intake or total tract DM digestibility. Neutral detergent fiber and ADF digestibilities were 5.4 and 3.7 percentage units higher (P < .05), respectively, for hay with a high vs low FB concentration. Forage chopping reduced (P < .05) DM, NDF, ADF, and CP digestibilities; the effect being similar for the two hay types tested. Results suggest that FB concentrations ranging from 2.9 to 5.5 mg/g of DM do not affect DM intake, however, nutrient digestion can be influenced by molding during field wilting or storage.

Genetic evaluation of lamb performance in Outaouais Arcott and Suffolk sheep, their crosses and Canadian Arcott- or Hampshire-sired three-breed crosses

A crossbreeding study was used to assess the growth performance of the Outaouais Arcott and Suffolk breeds, their two breed crosses and specific three-breed crosses sired by either Canadian Arcott or Hampshire rams. In a sheep flock maintained under a semi-confinement management system, Suffolk lambs, weighing 3.8 kg at birth, were not significantly heavier than Canadian Arcott- or Hampshire-sired crossbred lambs. Lambs of the Outaouais breed were 26% lighter (P < 0.05) than those of the Suffolk breed, and their two breed crosses had birth weights between the two parental purebreds. The relative ranks among the breeds and their crosses had not changed by 42 d of age with lamb weights ranging from 10.6 to 12.6 kg. By 120 d of age the Canadian Arcott- and Hampshire-sired lambs weighed approximately 28–29 kg and were not significantly different in weight from the Outaouais and Suffolk breeds and their two breed crosses. Additive and maternal genetic effects m the Suffolk breed were significantly greater than in the Outaouais breed for birth weight by 12.9 and 12.6% respectively. By 42 d, no difference was detected between breeds for direct genetic effect. However, the maternal effect favoured the Suffolk breed by 15.8% (P < 0.05). By 120 d, the direct genetic effect was significantly greater in the Outaouais breed by 9.8%, but maternal genetic effects continued to favour the Suffolk breed by 12.5% (P < 0.05). Heterosis effects were generally small (< 3.1%) and not significant for lamb weights. The terminal sire breeds showed no significant difference between Canadian- and Hampshire-sired lamb weights. Generally, results obtained for two analyses (least squares model and multi-trait animal model) of the same data set were consistent. However, the animal model would be preferable when estimating parameters and breeding values from an unbalanced data set with unequal subclass frequencies. Key words: Lambs, weight, genetic effects, heterosis, animal model

Genetic evaluation of ewe performance in Outaouais Arcott and Suffolk sheep and their crosses

Ewes from a newly developed sheep breed in Canada, the Outaouais Arcott, consistently out-performed Suffolk ewes in prolificacy at birth and at 42 d of age by 0.37 lambs at first parity and by 0.55 and 0.41 lambs, respectively, over all parities. In contrast, mean litter weights of Suffolk and Outaouais ewes did not differ at these times. Additive genetic effects in prolificacy and litter weight tended to favour the Outaouais breed over the Suffolk breed at first parity. Corresponding values over all panties were significant, favouring the Outaouais, for both prolificacy and litter weight at 42 d of age. Suffolk ewes excelled in maternal genetic effects for litter weight for all parities at birth and 42 d of age. Reciprocal cross ewes of the Outaouais and Suffolk breeds were similar (P > 0.05) in prolifacacy and litter weight. In general, crossbred ewes consistently exceeded Suffolk ewes in prolificacy but were not significantly different from Outaouais ewes. Though not always significant, crossbred ewes exceeded the average of their purebred parents m prolifacacy and litter weight. Furthermore, estimates of heterosis were always positive, and the 19% value for litter weight at 42 d of age at first parity was significant. This study, conducted over 6 yr, demonstrates the superiority of the Outaouais breed for production of commercial crossbred ewes to perform in a moderately intensive, semi-confinement operation. This superiority exists in addition to the previously-established ability of the Outaouais ewe to produce large litters in an 8-mo breeding cycle. Key words: Ewes, prolifacacy, litter weight, genetic effects, heterosis

The incidence and distribution of ochratoxin A in western Canadian swine

A survey of swine destined for slaughter in Manitoba was conducted to examine the incidence of ochratoxin A (OA) in swine herds from different regions of Manitoba throughout the year 1989-90. Thirty-six percent of the serum samples which were collected from 1600 pigs contained detectable levels of OA. The identity of this toxin was confirmed using liquid chromatography-mass spectrometry and enzymatic hydrolysis. There was a significant effect of the region from which the herds originated, as well as the season in which the samples were collected on both the incidence (p < 0.001) and concentration of OA (p < 0.001). In July, 65% of the samples contained detectable levels of OA, compared with 38, 21 and 17%, in April, October and January respectively. Furthermore, 24% of the samples collected in July contained greater than 15 ng/ml of OA, while only 2, 9, and 1% of the samples collected in April, October and January respectively, contained greater than 15 ng/ml of OA. Based on the six samples collected from each herd, it appears that the presence and concentration of OA within a herd may be estimated from a limited number of animals per herd.

A simple model for predicting the response of chicks to dietary enzyme supplementation

Two experiments with Leghorn chicks and data from five publications were analyzed to determine whether a simple general equation could be used to predict the relationship between the amount of a crude enzyme added to a diet and chick performance. The maximum improvements in weight gain and feed: gain ratio in Leghorn chicks fed rye diets containing different concentrations of enzymes were as high as 61 and 42%, respectively. Regression analyses demonstrated that there was usually a high linear correlation (r2 > 0.9, P < 0.05) between the concentration of the enzyme when transformed into its logarithmic value and weight gain or the feed:gain ratio. The general prediction equation was Y = A + B(logX), where Y is the performance value (i.e., weight gain, grams), A is the intercept (y-axis), B is the slope of the line (change in performance per units of enzyme in the diet), and X is the amount of enzyme in the diet. The slope of the line provides an index of the overall efficacy of the enzyme treatment. The log-linear model shows that for every ninefold increase in amount of enzyme in the diet (i.e., when the amount was increased to 10 times the starting amount), there was only a doubling of improvement in chick performance. High correlations (r2 values) were also obtained when data from the literature were analyzed. The equation was applicable to different classes and ages of poultry fed diets containing rye, wheat, barley, and lupins. These studies demonstrate that there is a linear relationship between the amount of enzyme added to the diet, when expressed as a logarithmic value, and the corresponding performance of chickens.

Variation in the mineral content of cereal grains grown at selected locations throughout Manitoba

Cultivars of wheat, barley, oats and rye were grown at 12 locations throughout Manitoba over 2 consecutive years. The concentrations of macrominerals Ca, P, Mg, K and S, and of microminerals Cu, Zn, Mn and Fe in the grains were determined and found to differ (P < 0.05) among cultivars of each grain. These differences among cultivars were considered to be minor, however, when comparisons between mineral concentrations and dietary requirements of economically important livestock were made. Location and year of growth (environmental variance) were factors affecting the concentrations of Cu, Zn and Mn, accounting for 72–96% of the total variance in these mineral concentrations (total variance = environmental variance plus cultivar × environmental variance). The concentrations of macrominerals in cultivars of wheat or barley differed among locations and year of growth, with cultivar × environment effects accounting for 25–50% of the total variance observed, except for S where these effects accounted for 86–87% of the total variance; this percentage was lower for oats and rye where a lower number of cultivars or locations was evaluated. Variation in mineral concentrations in the four Manitoba-grown grains was often considerable with coefficients of variation ranging from 8.5 to 40.1%. With all cereal grains, supplemental Ca, P, K, S, Cu, Zn, and Mn would be required to insure adequate dietary intakes for ruminants in general and Mg for lactating dairy cows, with Ca, P, Zn and Fe required for swine and poultry, Mn required for poultry and K required for some classes of poultry. Supplemental Cu would be required with wheat-based diets fed to swine and poultry. Key words: Minerals, wheat, barley, oats, rye, Manitoba

Effects of dietary fat source on sudden death syndrome and cardiac sarcoplasmic reticular calcium transport in broiler chickens

Wheat and soybean diets supplemented with either tallow or sunflower oil (SFO) were fed to broiler chicks. Variables examined included performance, incidence of sudden death syndrome (SDS), and cardiac sarcoplasmic reticular (SR) calcium transport. The phospholipid content of heart tissues was also determined. Birds fed the SFO diet gained significantly (P < .05) more weight over the first 21 days of age and had a significantly better feed:gain ratio (P < .01). The incidence of SDS mortality up to 39 days of age was also lower (P < .05) for SFO-fed birds than for those fed the tallow diet. Calcium (45Ca2+) uptake and calcium-magnesium 5'-adenosinetriphosphatase (Ca2+ + Mg(2+)-ATPase) activity in cardiac SR vesicles did not differ due to diet (P > .05). However, compared with similar weight pen-mates showing no disease signs, SDS birds had depressed 45Ca2+ uptake (P < .01) and Ca2+ + Mg(2+)-ATPase (P < .05) of cardiac SR vesicles. The phosphatidylcholine concentration in the cell membranes of heart tissue of tallow-fed birds was significantly higher (P < .05) than in SFO-fed chicks. No differences were seen in other phospholipid constituents. The SDS birds, however, had significantly (P < .05) lower phosphatidylethanolamine plus phosphatidylglycerol, sphingomyelin, and total phospholipid concentrations in the heart tissues than the pen-mate controls. The results support the hypotheses that SDS in broilers is a cardiac dysfunction associated with defective cardiac SR membrane function and that dietary fat type is implicated with the syndrome.

Estimation of nitrogen-corrected true metabolizable energy of two different barley samples with and without enzyme supplementation over different excreta collection times

The TMEn values of two barley samples and a corn sample with and without enzyme addition were determined in an experiment conducted over two consecutive weekly periods. Adult roosters were not influenced by the high beta-glucan content of Scout barley, which had a higher energy value (3.70 kcal/g DM) than the Bedford barley (3.44 kcal/g DM). Overall the energy value of the grain increased 3% due to enzyme supplementation. The 48-h excreta collection time was considered to be adequate for TMEn determination.