Eric D. Testroet

Feeding dried distillers grains with solubles affects composition but not oxidative stability of milk

Feeding lactating dairy cows dried distillers grains with solubles (DDGS) increases the concentration of unsaturated fatty acids in the milk from those cows, potentially leading to increased susceptibility to development of off-flavors. Feeding DDGS has been loosely implicated to be a cause of development of spontaneous oxidative off-flavor in milk. We hypothesized that increased feeding of DDGS would accelerate development of off-flavors and that fortification with vitamin E (0.06% wt/wt) or C (0.06% wt/wt) would prevent spontaneous oxidative off-flavors. The objective of this research was to determine the effects of feeding DDGS to lactating dairy cows on several parameters of milk quality as determined by both chemical and sensory evaluations. Twenty-four healthy mid-lactation Holstein dairy cows were fed total mixed rations containing DDGS (0, 10, or 25% dry matter). Cows were blocked by parity and randomly assigned to 1 of 2 groups (12 cows each). Each group received all 3 treatments in a 3-period Youden square design so that each cow served as her own control. Samples of milk from individual cows for proximate analysis and pooled milk for pasteurization and sensory analysis were collected on d 14, 21, and 28 of each experimental period. Pooled milk was assayed for peroxides and free fatty acids and evaluated by a trained sensory panel for the presence of 7 off-flavors common to milk on d 1, 3, and 7. Feeding 25% DDGS caused a significant decrease in daily milk yield. Increased dietary inclusion of DDGS also caused a concomitant decrease in percentage of milk fat and an increase in percentages of both solids nonfat and protein. Milk peroxides and free fatty acids were almost all below the detection limit, and the few exceptions were not found in replicated analyses. Sensory analysis revealed off-flavors only in milk from cows fed 0% DDGS when that milk was stored for 7d and when milk from cows fed 25% DDGS was fortified with 0.06% (wt/wt) vitamin C. Those few detected off-flavor scores were less than 1.5cm on a 15-cm line scale, indicating that the differences are not practically significant. Peroxide values support the findings by the sensory panel that both feeding DDGS at 10 and 25% and vitamin E and C fortification did not practically change the oxidative stability of milk. These results, taken together, indicate that feeding DDGS under our experimental conditions modified milk composition, but did not contribute to the development of off-flavors in milk.

Dried distillers grains with solubles do not always cause late blowing in baby Swiss cheese.

Late blowing in Swiss cheese, a result of unwanted gas production, is unacceptable to consumers and causes economic loss to manufacturers. Cheese processors have raised concerns that feeding dried distillers grains with solubles (DDGS) to cows leads to this defect, in part because of clostridial spores. We hypothesized that spores in DDGS would affect the quality of milk and baby Swiss cheese by promoting late-blowing defects. Thirty healthy multiparous and mid-lactation Holstein cows were fed total mixed ration containing DDGS (0, 10, and 20%; 10 cows per treatment group) by dietary dry matter in a 3×3 Latin square design. One complete milking from all cows within a treatment was collected and pooled for baby Swiss cheese, twice within each month of the 3-mo study. Additionally, individual milk samples from the 3 milkings of one day were collected weekly for proximate analysis. Incubation in reinforced clostridial medium-lactate medium tubes inoculated with milk, cheese, total mixed ration, or manure showed gas formation. Conversely, the DDGS used in our study did not contain gas-producing, spore-forming bacteria. Feeding 20% DDGS decreased milk fat percent and increased the solids nonfat, protein, and lactose percent of milk. After 60 d of ripening, baby Swiss cheese had typical propionic acid Swiss cheese aroma. Regardless of dietary treatment, pinholes, slits, splits, cracks, or a combination of these, were seen throughout most cheeses. Feeding of DDGS increased the amount of long-chain unsaturated fatty acids and decreased short-chain and most medium-chain fatty acids in the baby Swiss cheese. Although feeding cows diets with DDGS modified milk composition, and subsequently cheese composition, DDGS was not a source for gas-producing, spore-forming bacteria or for quality defects in Swiss cheese. Rather, the gas-producing, spore-forming bacteria likely originated from the environment or the cows themselves.

Short communication: No antimicrobial effects from one source of commercial dried distillers grains with solubles

Because residual antibiotics in dried distillers grains with solubles (DDGS) could lead to inadvertent feeding of antibiotics to animals, the objective of our study was to determine if a commercial DDGS contained antibiotics. The DDGS used in a feeding study, and milk from cows fed the DDGS, were below the detection limits for at least 17 antibiotics. Additionally, we evaluated if DDGS had any antimicrobial effect against Salmonella Typhimurium, Listeria innocua, Escherichia coli ATCC 25922, Staphylococcus aureus, Pediococcus acidilactici, Lactobacillus casei, Lactobacillus acidophilus, Bacillus licheniformis, Paenibacillus odorifer, Pseudomonas fluorescens, and Paenibacillus amylolyticus using the disk diffusion seeded agar overlay method. Neither the buffered nor nonbuffered water-soluble fractions of DDGS yielded clear zones around disks, indicating that the water-soluble DDGS fraction had no antimicrobial properties against any of the microorganisms tested. The absence of antibiotic residues in DDGS and milk samples in this study confirmed that this source of DDGS can be used as livestock feed without fear of inadvertent feeding of antibiotics.

A novel and robust method for testing bimodality and characterizing porcine adipocytes of adipose tissue of 5 purebred lines of pig

ABSTRACT Adipocyte sizes from adipose tissue of mature animals form a bimodal distribution, thus reporting mean cell size is misleading. The objectives of this study were to develop a robust method for testing bimodality of porcine adipocytes, describe the size distribution with an informative metric, and statistically test hypertrophy and appearance of new small adipocytes, possibly resulting from hyperplasia or lipid filling of previously divided fibroblastic cells. Ninety-three percent of adipose samples measured were bimodal (P < 0.0001); therefore, we describe and propose a method of testing hyperplasia or lipid filling of previously divided fibroblastic cells based upon the probability of an adipocyte falling into 2 chosen competing “bins” as adiposity increases. We also conclude that increased adiposity is correlated positively with an adipocyte being found in the minor mode (r = 0.46) and correlated negatively with an adipocyte being found in the major mode (r = −0.22), providing evidence of either hyperplasia or lipid filling of previously divided fibroblastic cells. We additionally conclude that as adiposity increases, the mode of the major distribution of cells occurs at a larger diameter of adipocyte, indicating hypertrophy.

Iodine values of adipose tissue varied among breeds of pigs and were correlated with pork quality

ABSTRACT Our objectives were to investigate fatty acid composition variation amongst adipose tissue sites, breed effects on fat quality, and the relationship of pork fat quality to fresh pork quality. Barrows and gilts (n = 347) of five purebred and one commercial crossbred line were fed commercial swine diets with DDGS inclusion at 30% (as fed) from 31.8 kg body weight until 30-d prior to harvest at 111.4 kg. Immediately after harvest, hot carcass weight was determined, adipose tissue was collected from the back, belly, and jowl, and meat samples were taken from the longissimus muscle for evaluation of pork quality. Iodine values (IV) varied between anatomical site and breed. Jowl fat IV were correlated to back and belly fat IV. Minor but significant correlations were observed between IV and meat quality characteristics. These results support our hypotheses that minor relationships exist between fat and fresh pork quality and that IV vary by anatomical location.

Lactational Performance of Holstein Dairy Cows Fed Two Levels of Full-fat Corn Dried Distillers Grains with Solubles

and Implications The lactational performance of 30 healthy multiparous Holstein dairy cows was tested when cows were fed 0, 10, and 20% dried distillers grains with solubles (DDGS) that contained 13.6% fat on a dry matter (DM) basis. Cows fed 10% DDGS on a DM basis experienced a reduction in milk fat percentage of 0.5 percentage points, but did not perform differently in other measures than did cows not fed DDGS. When cows were fed 20% DDGS on a DM basis, every common measure of feed utilization was impacted negatively. Introduction An important consideration when choosing any feed ingredient to include in a ration is the influence that the feed ingredient has on the productivity of the food-producing animal. Recently, increased ethanol production from corn in the Midwest has resulted in the increased availability of distillers grains and co-products. Moreover, dried distillers grains with solubles are often an economical protein source for animal production. Dried distillers grains with solubles (DDGS) are also a good source of rumen undegradable protein (RUP) in the ration of a lactating dairy cow. Prior research has indicated that DDGS can effectively be fed to lactating dairy cows without changing DMI or milk fat percentage while either not affecting or, in some cases, increasing yield of milk, energy corrected milk (ECM) yield, fat, protein and feed efficiency when compared with a traditional total mixed ration (TMR). Conversely, our prior research showed decreased milk fat percentage and milk yield when cows were fed 25% DDGS with 12.1% fat. Additionally, composition and nutritional value of DDGS can be highly variable, depending on manufacturing practices even within the same ethanol plant. As the ethanol industry has matured, however, so has the realized value of DDGS as a co-product rather than as a by-product. Consequently, ethanol production plants have developed more consistency in the nutritional quality of DDGS they produce. Therefore, it was the objective of this study to investigate the effects of feeding full-fat DDGS produced with current manufacturing practices on the feed efficiency and production performance of lactating Holstein dairy cows. In addition, based upon our prior research, we