M. S. Kerley

Effects of dietary supplementation with fructooligosaccharides on colonic microbiota populations and epithelial cell proliferation in neonatal pigs

Summary: Two experiments were conducted with neonatal pigs to determine the effects of feeding fructooligosaccharides on cecal and colonic microbiota, proliferation of cecal and colonic epithelial mucosa, and short-chain fatty acid concentrations in the cecum. Experiment 1 consisted of feeding neonatal pigs diets containing either 0 or 3 g fructooligosaccharides/L of formula for 15 days and then examining the large intestine for changes in cecal and proximal colonic microbiota; cecal pH; short-chain fatty acid concentrations; morphology of cecal, proximal, and distal colonic epithelial mucosa; gross necropsy; and his-topathology. Supplementation with fructooligosaccharides (FOS) did not alter cell counts of viable bifidobac-teria organisms or total anaerobic microbiota, cecal pH, or concentrations of short-chain fatty acids. Cecal mu-cosal cell density and labeled cells increased with FOS consumption. Proximal colonic mucosal crypt height, leading edge, labeled cells, proliferation zone, and labeling index increased with FOS consumption. Distal colonic mucosal crypt height, leading edge, cell density, labeling index, and labeled cells increased with FOS consumption. Gross necropsy and histopathology found no significant lesions. In Experiment 2, neonatal pigs were fed diets containing either 0 or 3 g fructooligosaccharides/L of formula for 6 days. Fecal samples were collected on the first full day of feeding and on days 3 and 6 after initiation of feeding. On days 1 and 3, concentrations of bifidobacteria were similar between diets; however, on day 6, pigs consuming FOS tended to have greater numbers of bifidobacteria (p = 0.08). These data suggest dietary consumption of FOS will enhance bifidobacteria populations and prevent colonic epithelial mucosa atrophy in neonates fed an elemental diet.

Genome-wide association analysis for feed efficiency in Angus cattle

Estimated breeding values for average daily feed intake (AFI; kg/day), residual feed intake (RFI; kg/day) and average daily gain (ADG; kg/day) were generated using a mixed linear model incorporating genomic relationships for 698 Angus steers genotyped with the Illumina BovineSNP50 assay. Association analyses of estimated breeding values (EBVs) were performed for 41 028 single nucleotide polymorphisms (SNPs), and permutation analysis was used to empirically establish the genome-wide significance threshold (P < 0.05) for each trait. SNPs significantly associated with each trait were used in a forward selection algorithm to identify genomic regions putatively harbouring genes with effects on each trait. A total of 53, 66 and 68 SNPs explained 54.12% (24.10%), 62.69% (29.85%) and 55.13% (26.54%) of the additive genetic variation (when accounting for the genomic relationships) in steer breeding values for AFI, RFI and ADG, respectively, within this population. Evaluation by pathway analysis revealed that many of these SNPs are in genomic regions that harbour genes with metabolic functions. The presence of genetic correlations between traits resulted in 13.2% of SNPs selected for AFI and 4.5% of SNPs selected for RFI also being selected for ADG in the analysis of breeding values. While our study identifies panels of SNPs significant for efficiency traits in our population, validation of all SNPs in independent populations will be necessary before commercialization.

Comparison of agar plate and real‐time PCR on enumeration of Lactobacillus, Clostridium perfringens and total anaerobic bacteria in dog faeces

Aims:  To compare agar plate and real‐time PCR methods on enumeration of total anaerobic bacteria, Lactobacillus and Clostridium perfringens in dog faeces.

Impact of reduced marker set estimation of genomic relationship matrices on genomic selection for feed efficiency in Angus cattle.

BackgroundMolecular estimates of breeding value are expected to increase selection response due to improvements in the accuracy of selection and a reduction in generation interval, particularly for traits that are difficult or expensive to record or are measured late in life. Several statistical methods for incorporating molecular data into breeding value estimation have been proposed, however, most studies have utilized simulated data in which the generated linkage disequilibrium may not represent the targeted livestock population. A genomic relationship matrix was developed for 698 Angus steers and 1,707 Angus sires using 41,028 single nucleotide polymorphisms and breeding values were estimated using feed efficiency phenotypes (average daily feed intake, residual feed intake, and average daily gain) recorded on the steers. The number of SNPs needed to accurately estimate a genomic relationship matrix was evaluated in this population.ResultsResults were compared to estimates produced from pedigree-based mixed model analysis of 862 Angus steers with 34,864 identified paternal relatives but no female ancestors. Estimates of additive genetic variance and breeding value accuracies were similar for AFI and RFI using the numerator and genomic relationship matrices despite fewer animals in the genomic analysis. Bootstrap analyses indicated that 2,500-10,000 markers are required for robust estimation of genomic relationship matrices in cattle.ConclusionsThis research shows that breeding values and their accuracies may be estimated for commercially important sires for traits recorded in experimental populations without the need for pedigree data to establish identity by descent between members of the commercial and experimental populations when at least 2,500 SNPs are available for the generation of a genomic relationship matrix.

The effect of residual feed intake classification on forage intake by grazing beef cows

Although feed intake and efficiency differences in growing cattle of low and high residual feed intake (RFI) classification have been established, little is known about the difference in grazed forage intake between beef cows of known RFI classification. Two experiments were conducted using Hereford cows for which RFI had been determined as heifers using the GrowSafe 4000E feed intake system, after which heifers had been divided into thirds as low RFI, mid RFI, and high RFI. During Exp. 1, 2 replicates of low and high RFI cows (n = 7/replicate) in mid- to late-gestation were blocked to 1 of 4 non-endophyte-infected tall fescue paddocks (1.8 to 2.4 ha), which they grazed continuously for 84 d during summer. Using grazing exclosures, weekly rising plate meter readings, and forage harvests every 21 d, average forage DMI was calculated. Low and high RFI groups did not differ (P > 0.05) in BW change or BCS change over the trial (19.5 vs. 22.1 kg of BW gain and 0.11 vs. 0.10 BCS gain), but low RFI cows had a 21% numerically lower DMI than high RFI cows (12.4 vs. 15.6 kg/d; P = 0.23). The average area needed per paddock over the trial was similar for low and high RFI cows (1.71 vs. 1.82 ha; P = 0.35), and the average DM on offer over the trial was less for low RFI than for high RFI cows (4,215 vs. 4,376 kg; P = 0.06). During Exp. 2, 3 replicates of low and high RFI cows with their calves (n = 4 pair/replicate) strip-grazed stockpiled and early spring growth tall fescue paddocks (0.7 to 0.9 ha) for 60 d in late winter and early spring. Because of limiting forage availability and quality at trial initiation, cow-calf pairs were also fed 3.31 kg/pair of pelleted soyhulls daily. Pre- and post-grazed forage samples were harvested for 4 grazing periods, and forage growth was estimated using a growing degree days calculation and on-site weather station data. Performance did not differ (P > 0.05) between low and high RFI cows throughout the experiment (18.4 vs. 26.6 kg of BW gain and -0.04 vs. 0.15 BCS gain). Despite the utilization of forage offered being similar for low and high RFI cow-calf pairs (P > 0.05), low RFI cows and their calves had an 11% numerically lower DMI than high RFI pairs (12.5 vs. 14.1 kg/d; P = 0.12). We concluded that either no intake differences existed between low and high RFI cows or that current methodology and small animal numbers limited our ability to detect differences.

Effect of dietary crude glycerol level on ruminal fermentation in continuous culture and growth performance of beef calves

Continuous culture and in vivo experiments were conducted to measure changes in ruminal fermentation and animal performance when crude glycerol was added to diets. For the continuous culture experiment (n = 6), diets consisted of 4 levels of crude glycerol (0, 5, 10, and 20%) that replaced corn grain. Dry matter and OM digestibility decreased linearly (P < 0.05) when crude glycerol increased in the diet, and no effect (P = 0.20 and 0.65, respectively) was observed for CP and NDF digestibility. Total VFA concentration and ammonia did not change (P > 0.05) due to crude glycerol level. Microbial efficiency increased quadratically (P = 0.012) as crude glycerol increased, whereas microbial N flow did not differ (P = 0.36) among treatments. As crude glycerol increased in the diet, crude glycerol digestibility decreased (P < 0.05). Seventy-two crossbred steer calves (250 ± 2.0 kg) were assigned to 4 treatments: 0, 5, 10, and 20% crude glycerol that replaced corn grain. Animals were fed for a total of 150 d. No differences (P = 0.08) between treatments were measured for DMI. Average daily gain and GF responded quadratically (P < 0.05), with 10% crude glycerol resulting in the greatest values. In the second in vivo experiment, 100 crossbred steer calves (300 ± 2.0 kg) were assigned to 5 treatments: 0, 5, 10, 12.5, or 15% crude glycerol replaced corn grain. Calves were fed for a total of 135 d. No significant differences (P > 0.05) were measured in growth performance. For Exp. 3, one hundred heifer calves (270 ± 2.0 kg) were assigned to 4 treatments: 0, 5, 10, or 20% crude glycerol that replaced hay. No differences (P > 0.05) were measured in animal performance. We concluded that crude glycerol addition to a diet did not negatively affect ruminal fermentation, and addition of up to 20% in concentrate and hay-based diets should not affect performance or carcass characteristics.

Nutritional skewing of conceptus sex in sheep: effects of a maternal diet enriched in rumen-protected polyunsaturated fatty acids (PUFA)

BackgroundEvolutionary theory suggests that in polygynous mammalian species females in better body condition should produce more sons than daughters. Few controlled studies have however tested this hypothesis and controversy exists as to whether body condition score or maternal diet is in fact the determining factor of offspring sex. Here, we examined whether maternal diet, specifically increased n-6 polyunsaturated fatty acid (PUFA) intake, of ewes with a constant body condition score around the time of conception influenced sex ratio.MethodsEwes (n = 44) maintained in similar body condition throughout the study were assigned either a control (C) diet or one (F) enriched in rumen-protected PUFA, but otherwise essentially equivalent, from four weeks prior to breeding until d13 post-estrus. On d13, conceptuses were recovered, measured, cultured to assess their capacity for interferon-tau (IFNT) production and their sex determined. The experiment was repeated with all ewes being fed the F diet to remove any effects of parity order on sex ratio. Maternal body condition score (BCS), plasma hormone and metabolite concentrations were also assessed throughout the study and related to diet.ResultsIn total 129 conceptuses were recovered. Ewes on the F diet produced significantly more male than female conceptuses (proportion male = 0.69; deviation from expected ratio of 0.5, P < 0.001). Conceptus IFNT production was unaffected by diet (P > 0.1), but positively correlated with maternal body condition score (P < 0.05), and was higher (P < 0.05) in female than male conceptuses after 4 h culture. Maternal plasma hormone and metabolite concentrations, especially progesterone and fatty acid, were also modulated by diet.ConclusionThese results provide evidence that maternal diet, in the form of increased amounts of rumen-protected PUFA fed around conception, rather than maternal body condition, can skew the sex ratio towards males. These observations may have implications to the livestock industry and animal management policies when offspring of one sex may be preferred over the other.

Hardwood silvopasture management in North America

Hardwood silvopasture management has great potential throughout the Central Hardwood Region in the United States, but has been little utilized due to the lack of available information on its application. However, more than one-third of farm woodlands within the region are being grazed without the benefit of the application of silvopasture principles. The University of Missouri Center for Agroforestry has undertaken a major research initiative to further develop and build upon the fragmented information that is available on hardwood silvopastoral management. Ten years of screening forage species (grasses and legumes) for shade tolerance has clearly demonstrated that many cool-season forages benefit from 40% to 60% shade when grown in Missouri – a finding that could likely be extrapolated to the entire region of the Midwestern United States. Grazing trials have proven to be successful in the short-term. Long-term research is currently underway to fully document the interactions between hardwood trees, cattle and forage.

Use of lignin extracted from different plant sources as standards in the spectrophotometric acetyl bromide lignin method

A nongravimetric acetyl bromide lignin (ABL) method was evaluated to quantify lignin concentration in a variety of plant materials. The traditional approach to lignin quantification required extraction of lignin with acidic dioxane and its isolation from each plant sample to construct a standard curve via spectrophotometric analysis. Lignin concentration was then measured in pre-extracted plant cell walls. However, this presented a methodological complexity because extraction and isolation procedures are lengthy and tedious, particularly if there are many samples involved. This work was targeted to simplify lignin quantification. Our hypothesis was that any lignin, regardless of its botanical origin, could be used to construct a standard curve for the purpose of determining lignin concentration in a variety of plants. To test our hypothesis, lignins were isolated from a range of diverse plants and, along with three commercial lignins, standard curves were built and compared among them. Slopes and intercepts derived from these standard curves were close enough to allow utilization of a mean extinction coefficient in the regression equation to estimate lignin concentration in any plant, independent of its botanical origin. Lignin quantification by use of a common regression equation obviates the steps of lignin extraction, isolation, and standard curve construction, which substantially expedites the ABL method. Acetyl bromide lignin method is a fast, convenient analytical procedure that may routinely be used to quantify lignin.

Source of dietary fiber fed to dogs affects nitrogen and energy metabolism and intestinal microflora populations

Twenty-eight adult ovariohysterectomized dogs were fed one of four diets differing in type of dietary fiber to assess the effects of fiber on energy digestibility, partitioning of nitrogen (N) components, and changes in intestinal microflora. Dietary fiber sources were beet pulp (BP), short-chain fructooligosaccharides (FOS), cellulose (C) and a fiber blend (FB; BP, gum talha, and FOS). Dry matter (DM) intake was reduced and DM digestibility was increased for dogs fed the FOS diet. Fecal N and microbial N excretion (g/day) was greater with the FB diet. This diet tended to reduce urinary N excretion. Bacterial characterization of intestinal contents found that FOS increased total aerobic bacteria in the distal colon. Fiber Blend decreased counts of Clostridium spp. in the ileum. We concluded that fermentable fiber sources increase microbial growth in the colon, and have the potential to trap and remove N from the body.