S.J. Taylor

Can fatty acid and mineral compositions of sturgeon eggs distinguish between farm-raised versus wild white (Acipenser transmontanus) sturgeon origins in California? Preliminary report

The objective was to investigate the potential of using fatty acid and mineral compositions of sturgeon eggs to distinguish their source, either farm-raised or wild fish. Trafficking of illegally obtained wild white sturgeon eggs is a major concern to the California Department of Fish and Game, but there is no forensic method to separate wild and farm-raised white sturgeon eggs. The extension of these findings in future work will be to use the fatty acid and mineral compositions as forensic indicators of caviar produced legally from farm raised sturgeon compared with illegal caviar produced from sturgeon poached from the wild. Samples (10) of sturgeon eggs were collected from a commercial aquaculture facility in the Sacramento Valley. Eggs from wild sturgeon (9) were obtained primarily from confiscations of illegally caught sturgeon by fish and game law enforcement personnel. The total lipid content of sturgeon eggs was analyzed for fatty acid composition. The most notable difference was the higher concentration (P<0.001) of C18:2n6 in farm raised eggs (6.5 mg/100g total lipid) than wild eggs (0.6 mg/100g total lipid) while other differences between fatty acids were smaller. Eicosapentaenoic acid (C20:5n3) was higher (P<0.02) in farm-raised (5.56 mg/100g) than wild (4.49 mg/100g). Docosahexaenoic acid (C22:6n3), C18:1 cis 9&10, and C20:4n6 were not different for origin of the eggs. Concentration of selenium was markedly higher (P<0.001) in eggs from wild sturgeon (10.0 mg/kg dry weight) than farm-raised sturgeon (2.7 mg/kg dry weight). Concentrations of iron, zinc, copper, phosphorus, sulfur, calcium, and potassium did not differ between farm-raised and wild eggs. Arsenic concentration in wild eggs was 3.3mg/kg dry weight whereas arsenic was not detected in the farm-raised eggs. Fatty acid and mineral compositions of eggs differed significantly between farm-raised and wild sturgeon and these should be investigated further as biological markers for forensic identification of caviar origin.

Tomato seeds as a novel by-product feed for lactating dairy cows

Whole tomato seeds, a novel by-product feedstuff, were fed to lactating Holstein cows to determine the nutritive value of whole tomato seeds by replacing whole cottonseed in the total mixed ration. Four primiparous and 4 multiparous Holstein cows were used in a 4×4 Latin square design and fed 1 of 4 total mixed rations. Whole tomato seeds replaced whole cottonseed on a weight-to-weight basis for lipid. The proportion of whole tomato seeds to whole cottonseed in the diets were 100:0, 50:50, 25:75, and 0:100 on a lipid basis. Thus, tomato seeds were 4.0, 2.4, 1.1, and 0% of the ration dry matter, respectively. Milk yield and the concentrations and yields of protein, lactose, and solids-not-fat did not differ for the effect of diet. However, milk fat concentration decreased and milk fat yield tended to decrease as whole tomato seeds replaced whole cottonseed. Intakes of dry matter, lipid, and crude protein did not differ. Whole-tract apparent digestibility of dry matter and ash-free neutral detergent fiber did not differ, but digestibility of total fatty acids and crude protein decreased with increasing proportion of whole tomato seeds. Urea concentration in milk and plasma both decreased with increasing whole tomato seeds. Fecal concentration of linoleic and α-linolenic acids increased with increasing whole tomato seeds, suggesting that seeds were passing out of the digestive tract undigested. The concentrations of C18:2n-6 and C18:3n-3 in milk fat had small increases, but their yields were not different, suggesting that only a small amount of whole-tomato-seed lipid might have been digested postruminally. Amounts of trans C18:1 fatty acids in milk fat were higher with increasing whole cottonseed, which might suggest a shift in rumen biohydrogenation pathways. At the level of feeding used in the current study, whole tomato seeds replaced whole cottonseed in the diet of lactating dairy cows without a change in production.

Experiential learning exercises to enhance learning in a university nutrition course

ABSTRACT Two projects were conducted in a University of California–Davis undergraduate animal nutrition class as experiential learning experiences to reinforce concepts taught in the lectures. The objectives of the experiential learning exercises were to (1) reinforce the nutritional concepts that were presented in the lectures, (2) provide hands-on experiences with animals as well as analytical wet chemistry methods, (3) study fiber digestion and lipid metabolism as they relate to digestive systems, and (4) inspire students to learn more about nutrition. Students participated in project 1 to study the digestibility of NDF in sheep, horses, and rabbits and project 2 to study dietary lipid digestion and metabolism in mice. Both projects required participation outside of normal class time. Students were involved in collecting and analyzing samples, recording and analyzing data, and interpreting and reporting their findings. Project 1 concluded with graded written and oral reports, whereas project 2 concluded with summarization of findings. Students were asked at the end of the class to rate both projects on a scale from 1 to 5, with 5 being the best rating. Project 1 received an average of 4.4, and project 2 received an average of 3.7.

Saturation Ratio of Supplemental Dietary Lipid on Production Performance of Holstein Cows

Abstract Two experiments were conducted to evaluate the effect of supplemental lipid varying in proportion of unsaturated and saturated fatty acids on lactation performance and milk composition. All diets (45% chopped alfalfa hay and 55% concentrates) contained 12% whole cottonseed (as-fed) and were fed as a TMR. Treatments were no supplemental lipid (control, 3% total fatty acids, DM basis) or the addition of2% supplemental lipid from tallow, yellow grease, or a blend (60% tallow:40% yellow grease). In Exp. 1, 48 cows were assigned to their treatment diets beginning wk 4 and ending wk 18 of lactation. In Exp. 2, 4 cows that completed Exp. 1 were enrolled in a 4 x 4 Latin square with 2-wk periods to further study the effects of saturation ratio of the supplemental lipids on milk composition. In Exp. 1, no treatment effects were observed for DMI, milk production, or milk composition; however, 4% fat-corrected milk tended to increase and fat yield increased for lipid-supplemented treatments. In Exp. 2, DMI, milk production, and percent and yield of milk fat increased in lipid-supplemented treatments. Digestible energy intakes tended to increase when yellow grease was the lipid source compared with tallow. In both experiments, milk fatty acid composition was affected by supplemental lipid as well as the source of supplemental lipid. No effects on lactation performance were evident due to the differences in the un-saturated to saturated fatty acid composition of the supplemental lipid source.