Performing Department
Animal Science
Non Technical Summary
Livestock researchers at the University of Wyoming, Department of Animal Science, have determined that supplementing grazing cattle with calcium salts of omega-3 (n-3) fats originating from fish oil result in deposition of these fatty acids in the meat. Delivery of the fatty acid calcium salt to grazing livestock in a true production setting of use to livestock producers, however, is not developed well enough to adopt such a supplementation strategy. The research will begin with testing of a molasses-based lick tub in which calcium salts of fish oil fatty acids are mixed with hot, dried molasses and then allowed to cool in a tub so that cattle can have free access to it in such a way that the animals will lick the molasses and consume the fatty acids along with the molasses carrier. This dried molasses lick tub approach to supplementing other types of nutrients is currently in use and available commercially. Over the course of the research described herein, the investigators will study the effects of fish oil-based omega-3 fatty acids on several important aspects of livestock production: how will these dietary fatty acids influence their concentrations in the meat, and how will their presence affect flavor of the meat? In addition to deposition in meat, evaluation of omega-3 levels in reproductive tissue of heifers will be determined to initiate investigations into the impact of these omega-3 fats on reproductive efficiency of heifers, cows, and ewes. The potential impact of omega-3 fatty acid supplementation on calf development and immune system health will be evaluated in calves reared on dams consuming these supplements during lactation. Thus milk concentrations will be determined with subsequent estimation of calf intake. Calves will be followed during development to determine how their health would be affected in terms of immune status and response to challenges, such as shipping. In addition to the bovine work, investigations with sheep are proposed so that evaluation of the potential effectiveness in growing lambs and reproduction in ewes can be assessed. This work will be performed by the investigators listed above, along with assistance from technical personnel and graduate students.
Animal Health Component
0%
Research Effort Categories
Basic
80%
Applied
10%
Developmental
10%
Goals / Objectives
Major Goal: To determine the effectiveness of rumen-inert long-chain omega-3 fatty acids on growth and reproductive parameters in cattle and sheep.Objectives:1: Determine the effectiveness of molasses lick tubs as a delivery system for long-chain n-3 fatty acids, when present as the calcium salt (rumen inert) of fish oil, for supplementation of grass-fed beef cattle.2: Determine the effects of supplemental long-chain n-3 fatty acids on reproductive efficiency of beef cows and heifers when the fatty acids are provided as the calcium salt of fish oil using the molasses lick tub delivery system.3: Determine the impact of cow and heifer rumen inert n-3 fatty acid supplementation on milk fatty acids and calf health.4: Determine the effectiveness of molasses lick tubs as a delivery system for long-chain n-3 fatty acids, when present as the calcium salt (rumen inert) of fish oil, for supplementation of forage fed lamb.5: Determine the effects of supplemental long-chain n-3 fatty acids on reproductive efficiency of ewes when the fatty acids are provided as the calcium salt of fish oil using the molasses lick tub delivery system. Additionally, the impacts on milk composition and lamb health will be determined.
Project Methods
Animals and Diets: Twenty-seven heifers from the University of Wyoming beef herd (approximately 360 kg body weight) will be used in a 126-day replicated 3 × 3 Latin square designed experiment. Heifers will be blocked by initial body weight (each square) and randomly allotted (3 heifers per pen) to one of 9 total pens at the Laramie Research & Extension Center Beef Unit. Nine observations for each treatment are needed. The heifers will receive a basal diet consisting of low-, medium-, or high-quality forage for 3 consecutive 42-day periods with forage quality assessed by concentration of crude protein. The forages used in this study are expected to consist of mature grass hay, good quality grass hay, and alfalfa hay, with forage crude protein (% nitrogen × 6.25) concentrations of approximately 6-7%, 11-13%, or 17-18%, respectively.In each period, heifers will be fed the basal diet (forage only) for 14 days. This adaptation period should permit sufficient turnover of ruminal contents, as well as allow for rumen microbial adaptation to the current forage. To mimic an accurate producer situation, no lick tub supplement will be provided during the 14-day adaptation because in practice cattle will have been adapted to their forage before they are provided the lick tubs. On day 14 of each period, each pen of cattle will be provided with a 113-kg lick tub of dried molasses that will contain 35% by weight of calcium salts of fish oil fatty acids for the subsequent 28 days. One tub will be placed in each pen and replaced when the tub is about 90% consumed. Hay will be weighed daily into a feed bunk for each pen. Stored forage samples for each forage type and each period will be composited so that 18 forage samples will be analyzed at the end of the study. Tubs will be weighed weekly by suspending from a hoist attached to a scale.Sample Collection and Analyses: Initial blood samples will be taken from each heifer at the start of the study. On day-14 of each period (when lick tubs are added) the first blood sample of the period will be obtained. Blood samples will be taken again at days 21, 28, 35, and 42 of the period. This blood sampling schedule will allow us to determine the rate of change in plasma concentration of EPA/DHA. At each blood sampling, heifer body weight will also be measured.Fatty acids will be measured using gas/liquid chromatography.Forage dry matter will be determined initially by freeze drying the composited samples. For subsequent analyses dry matter will be determined by convection drying at 55°C for 48 hours. Total ash will be determined by weighing the residue of a 0.5 g sample after incinerating at 500°C for 4 hr in a muffle furnace. Crude protein concentration will be calculated from the nitrogen concentration, which will be determined using the LECO nitrogen analyzer. The common conversion factor of 6.25 will be used to convert percentage nitrogen to crude protein. Acid detergent fiber and neutral detergent fiber will be determined using well-established procedures in our laboratory employing the ANCOM fiber analyzer. Fatty acid composition of forage lipids will be determined according to protocols described in the previous section. In vitro dry matter digestibility will be determined by incubating 1.0 g of ground forage in aliquots of ruminal fluid along with buffers to mimic the rumen environment. In vitro dry matter digestibility measurement will allow for quantification of differences in forage quality not apparent by comparison of only crude protein.Statistical analysis: Data will be analyzed as a replicated 3 × 3 Latin square designed experiment. The study will involve repeated measures with blood samples taken weekly for 4 weeks during each period. Independent variable of forage quality treatment, along with fixed effects of period, will be used in the MIXED procedure of SAS to determine effects on plasma fatty acid composition and fatty acid composition × time within each period, as well as forage intake and lick tub intake. If forage intake and/or lick tub intake are affected by forage quality, forage intake and/or lick tub intake will be used as covariates to adjust for forage quality treatment effects. Specifics for statistical analysis will be accomplished after consulting with a statistician.Efforts:The proposed research will be suitable for one publication in the Journal of Animal Science, which will represent the peer-reviewed scientific publication and technology transfer. In addition, we will publish an abstract and proceedings of the research, along with presentation at the Western Section American Society of Animal Science conference in June 2015 in Las Cruces, New Mexico. Presentation of research at this conference will be the culmination of the graduate student training opportunity that this project will provide. For outreach purposes we will present the study at R&E Center field day events at Laramie and Lingle, WY if appropriate. The research also represents ongoing efforts to develop supplementation strategies for increasing long-chain omega-3 fatty acids in tissues of beef cattle. We plan to combine results of the previous two studies conducted at the SAREC facility with the proposed work for a popular press article that will have farther reaching appeal to our producer stakeholders in the region and nationally. The strategic issue of boosting U.S. agricultural production will be addressed by the results through alternatives to conventional agricultural practices that could increase reproductive efficiency and increase long-chain omega-3 fatty acids in forage-finished beef without the need to over finish cattle while on grass or harvested forage.Evaluation:The relevance of the proposed research will be demonstrated by evaluating interactions of forage quality with uptake of n-3 fatty acids in blood plasma, which will provide producers with a clearer estimate of how their forage impacts availability of these fatty acids for potential nutraceutical use. Moreover, the molasses lick tub delivery system will provide producers with a much reduced labor alternative for group feeding in a pasture setting to supplement these fatty acids. Effectiveness of this supplementation system to impact reproductive efficiency in heifers remains to be tested and will be a significant focus of research for which future funding will be sought. Generally, the success of the project will be measured by the increased reproductive efficiency that producers can realize when this supplementation strategy is put into practice.