Evaluating the Rumen Degradation of Novel Protected Gelatin Capsules Containing Fish Oil Fed to Lactating Dairy Cows

SIMPLE SUMMARY: An increased intake of polyunsaturated fatty acids has been associated with beneficial effects in human health such as a reduction in susceptibility to cardiovascular and autoimmune diseases. However, due to rumen microbial processes, most of the polyunsaturated fatty acids fed to ruminants are changed to saturated forms that the cow can use. Thus, only a small percentage of the fatty acids contained in the cow’s diet reach the intestine and are further incorporated into milk and meat. In this study we conducted two trials to evaluate the effect of feeding rumen-protected capsules containing fish oil on lactation performance, rumen fatty acids content and milk enrichment of fatty acids in the two major dairy breeds. The results of this study showed that the capsules did not increase the concentration of the desired fatty acids, but they reduced their degradation rate in the rumen. A further test showed that the capsules experienced a reduction in shell hardness when exposed to high levels of moisture, leading to abrasion that decreased the effectiveness of the treatments in the two trials. Thus, future studies are warranted to evaluate alternative methods, such as coating, to minimize the contact between the capsule shell and environmental moisture. ABSTRACT: The objective of this study was to assess the effects of feeding gelatin capsules containing fish oil, treated with alcoholic solutions of flavoring agents followed by drying, on lactation performance, rumen fatty acids content and milk enrichment of fatty acids. In Trial 1, four multiparous ruminally fistulated Holstein cows were randomly assigned to one of four dietary treatments sequences in a 4 × 4 Latin square design. Treatments consisted of (1) Control with no capsules, (2) Control plus 200 untreated capsules per cow/day, mixed with the TMR, (3) Control plus 200 treated capsules per cow/day placed directly into the rumen, (4) Control plus 200 treated capsules per cow/day, mixed with the TMR. In Trial 2, three fistulated Holstein and three fistulated Jersey multiparous cows were randomly assigned to three dietary treatments sequences in a replicated 3 × 3 Latin square design. Treatments consisted of (1) Control with no capsules fed to the cows, (2) Control plus 180 untreated capsules per cow/day, (3) Control plus 180 treated capsules per cow/day. Compared to control, feeding fish oil capsules significantly (Trial 1) or numerically (Trial 2) reduced milk fat concentration and yield. Furthermore, in both trials, the feeding of untreated or treated capsules had no effect on animal performance or milk composition. In both trials, compared to controls, supplementing the diet with fish oil capsules consistently increased total trans C18:1 isomers and DHA concentration in the rumen and milk fat. However, for both trials, capsule protection treatment had a minimal effect on the concentration of any of the reported rumen and milk fatty acids. When assessed under laboratory control conditions, due to water absorption, the treated capsule weight was increased by 40% while resistance to pressure decreased by 84% after 2 h of incubation in water. The results of this study suggest that due to a reduction in the capsule shell’s resistance to abrasion, treated capsules marginally prevented the release of fish oil in the rumen.