The objective of this study was to evaluate and to estimate the relationship between fecal egg counts (FEC) and FAMACHA© score and the body weight of growing Katahdin rams during a parasite challenge. One of the largest factors negatively influencing reproduction and economics in the sheep industry is gastrointestinal nematode (GIN) parasites. Due to anthelmintic resistance of these parasites, animals are selected for parasite resistance using FEC and FAMACHA© scores. Data were used from the Virginia Tech Southwest Agricultural Research and Extension Center Ram Test in Glade Spring, VA from the years 2012 to 2018 in which animals were tested in 14-day intervals for 70 days. Mixed models for repeated weight measurements were made from backwards stepwise selection to evaluate relationships between weight and GIN FEC. A total of 576 animals within 23 contemporary groups derived from test year and pasture group were analyzed. Ram, contemporary group, and consignor were considered random effects, and fixed effects were birth type, test day, age, age squared, starting weight, FEC, and FAMACHA© score. Pairwise contrasts were used in the statistical analysis of parameters and their interactions. Weight and age were found to have a quadratic relationship. Increased FEC was associated with weight loss at a rate of 0.00030 kg/FEC (P < 0.0001). Animals dewormed at any point during the trial weighed less than those that were not and increased with test day to a maximum difference of 4.66 kg (P < 0.001). FAMACHA© score was found to be significant (P < 0.05), but a direct relationship with weight was not conclusive. Overall, rams with severe enough parasite load to require deworming had lesser weights, which could impact profitability of sheep production and reinforced the need to select animals that had greater innate parasite resistance.

Using polyhydroxyalkanoate (PHA) materials for ruminal boluses could allow for longer sustained release of drugs and hormones that would reduce administration time and unneeded animal discomfort caused by continuous administration. The objective of this study was to determine ruminal degradability and kinetics of biodegradable polymers and blends. A proprietary PHA-based polymer, poly(butylene succinate-co-adipate) (PBSA), PBSA:PHA melt blends, and forage controls were incubated in rumen fluid for up to 240 h. Mass loss was measured after each incubation time, and digestion kinetic parameters were estimated. Thermogravimetric, differential scanning calorimetry, and intrinsic viscosity analyses were conducted on incubated samples. Generally, across treatments, mass loss was significant by 96 h with a minimum increase of 0.25% compared to 0 h but did not change thereafter. Degradation kinetics demonstrated that polymer treatments were still in the exponential degradation phase at 240 h with a maximum disappearance rate of 0.0031 %/h. Melting temperature increased, onset thermal degradation temperature decreased, and intrinsic viscosity decreased with incubation time, indicating structural changes to the polymers. Based on these preliminary findings, the first stage of degradation occurs within 24 h and PHA degrades slowly. However, further ruminal degradation studies of biodegradable polymers are warranted to elucidate maximum degradation and its characteristics.

The objective of this study was to compare the nutritional composition and the neutral detergent fiber (NDF) degradation kinetics of brown midrib (BMR) and non-BMR genotypes within and across warm-season annual grasses. Four commercial varieties (two non-BMR and two BMR) of corn, sorghum, and pearl millet were planted in plots. Forage samples were incubated in the rumen of three rumen-cannulated cows for 0, 3, 6, 12, 24, 48, 96, and 240 h. On an NDF basis, all forage types showed lower acid detergent lignin (ADL) concentrations for BMR genotypes, but the magnitude of the difference differed among forage types. The concentration of undegraded NDF (uNDF; NDF basis) differed among forage types and between genotypes. Corn had the least, pearl millet had the intermediate, and sorghum had the greatest concentration of uNDF. Non-BMR genotypes had greater concentrations of uNDF than BMR genotypes. No interaction existed between forage type and genotype for the concentration of uNDF. In conclusion, although BMR forages may show lower ADL concentrations in the cell wall and greater NDF degradability than non-BMR forages of the same forage type, BMR forages do not always have the least ADL concentration or the greatest NDF degradability when comparing different forage types.

Due to the occurrence of plastic impaction in ruminants and its deleterious effects on health and production, it is necessary to determine the suitability of biodegradable polymers to replace polyethylene-based agricultural plastics, such as hay netting. The objectives of this study were to evaluate the clearance of a polyhydroxyalkanoate (PHA) and poly(butylene succinate-co-adipate) (PBSA) melt-blend polymer from the rumen when fed to cattle and subsequent animal health. Twelve Holstein bull calves were dosed with an encapsulated 13.6 g of PBSA:PHA (Blend), 13.6 g of low-density polyethylene (LDPE), or four empty gelatin capsules (Control) for 30 d. The feed intake, body weight, and body temperature were evaluated, and hemograms were run on d 0 and d 30. On d 31, calves were euthanized to evaluate gross rumen measurements and pathology, papillae length, and polymer residues in rumen contents. No calves presented any signs related to plastic impaction. The feed intake; body weight; rectal temperature; hematological parameters; gross rumen measurements and pathology; and rumen pH and temperature were not affected by treatments. Calves dosed with LDPE had 27 g of undegraded polymer retained in the rumen while Blend calves had only 2 g of fragmented polymers that were 10% of their original size. Agricultural plastics developed from PBSA:PHA may be a suitable alternative to LDPE-based products in the case of animal ingestion and may reduce the incidence of plastic impaction.

Replacing undigestible, polyethylene-based agricultural plastics like net wrap with biodegradable alternatives polyhydroxyalkanoate (PHA) and poly(butylene succinate-co-adipate) (PBSA) may reduce the incidence of plastic impaction in ruminants. The objectives of this study were to evaluate the ruminal clearance of PBSA:PHA compared to low-density polyethylene (LDPE) and to evaluate animal health when these materials are fed. Twelve Holstein bull calves, blocked by age and weight, were randomly allocated to one of three daily bolus treatments for 30d: 13.6g of PBSA:PHA in 4 capsules (Blend), 13.6g of LDPE in 4 capsules (LDPE), or 4 empty capsules (Control). Hemograms were conducted on blood samples collected on d0 and d30. On d31, animals were sacrificed to evaluate gross rumen measurements, pathology, and papillae length, and to characterize polymer residues in rumen contents. Data were analyzed with PROC MIXED in SAS and least squared differences were adjusted by Tukey’s method. No animals presented any symptoms related to plastic impaction and animal health was not affected by treatment. Daily grain and hay intake, body weight, rectal temperature, hematological parameters, gross rumen measurements and pathology, and rumen pH and temperature were not affected by treatment. Methylene blue reduction time of Blend calves tended to be decreased by 30% compared to LDPE calves (P=0.06), and caudal ventral papillae length of Blend calves were 50% longer than those of Control animals (P< 0.01). Thus, PBSA:PHA may have beneficial impacts. Calves dosed with LDPE retained 27.42g of undegraded polymer in the rumen while 1.72g of fragmented polymers 10% of their original size were detected in Blend calves (P< 0.01). Our results indicate that if net wrap is developed from PBSA:PHA and incorporated into ruminant feed, aggregation of filamentous material will not occur in the rumen, and incidences of plastic impaction will be decreased compared to net wrap developed from LDPE.