Location: Livestock Issues ResearchTitle: Dehydrated citrus pulp alters feedlot performance of crossbred heifers during the receiving period and modulates serum metabolite concentrations pre- and post-endotoxin challenge Author
|Cribbs, Joshua - Texas Tech University|
|Young, Tanner - Texas Tech University|
|Jennings, Mathew - Texas Tech University|
|Carroll, Jeffery - Jeff Carroll|
|Schmidt, Ty - University Of Nebraska|
|Johnson, Bradley - Texas Tech University|
|Rathmann, Ryan - Texas Tech University|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/2015
Publication Date: 12/3/2015
Citation: Cribbs, J.T., Young, T.R., Jennings, M.A., Sanchez, N.C., Carroll, J.A., Callaway, T.R., Schmidt, T.B., Johnson, B.J., Rathmann, R.J. 2015. Dehydrated citrus pulp alters feedlot performance of crossbred heifers during the receiving period and modulates serum metabolite concentrations pre- and post-endotoxin challenge. Journal of Animal Science. 93:5791-5800.
Interpretive Summary: This study was a collaborative effort between scientists at Texas Tech University, the Livestock Issues Research Unit, the Food and Feed Safety Research Unit, and the University of Nebraska. Citrus production is a major agricultural commodity in many tropic regions across the globe. Citrus by-products are utilized in livestock diets to offset disposal costs and simultaneously provide an economical feedstuff alternative. Dried citrus pulp (DCP) replacement of starch-rich concentrates in the diet may yield a positive associative effect on fiber digestion while cattle are being systematically transitioned to finishing diets. Studies utilizing DCP in a feedlot setting are lacking. Therefore, this study was designed to determine if inclusion of DCP in the diet of receiving cattle impacted feedlot performance and morbidity, and determine if DCP influenced the metabolic response of cattle to a lipopolysaccharide challenge. Results from this study demonstrate that utilizing DCP in feedlot diets may cause palatability issues that result in decreased feed intake and weight gain. However, cattle adjust to the inclusion of DCP in the feed over time. Further, cattle fed DCP had elevated non-esterified fatty acid concentrations yet lower glucose concentrations in response to a lipopolysaccharide challenge. Additional research is required to improve palatability of the DCP in order to capitalize on the economic and health benefits associated with DCP used in receiving diets. These data will be of use to scientists working in the areas of cattle health and nutrition, as well as cattle producers interested in utilizing alternative feed ingredients. The information provided can provide insight into the advantages and disadvantages of utilizing citrus by-products in cattle feed.
Technical Abstract: English x Continental heifers (n=180) were sourced in two loads (188.7 ± 18.0 kilograms and 225.2 ± 22.2 kilograms body weight, respectively) from commercial auction barns to study the effects of feeding dehydrated citrus pulp (DCP) on feedlot performance of newly received heifers. A completely randomized block design was utilized with body weight nested within arrival load and blocked by body weight into three dietary treatments (36 pens; 5 heifers/pen; 12 blocks; 3 pens/block; 12 pens/treatment). Treatment diets contained: 1) 0% DCP (Control; CON); 2) 10% DCP; or 3) 20% DCP on a DM basis. Diets containing DCP were exchanged with steam flaked corn on a 1:1 basis. Cattle were fed a 63, 73, and 83% concentrate diet from day 0 to 28, day 28 to 42, and day 42 to 56, respectively. Over the 56 day trial period, as the amount of dietary DCP increased DMI decreased (P = 0.01), average daily gain decreased (P < 0.01), and Gain: Feed decreased (P = 0.02). From d 0 to d 28 there was no difference in the observed minus the predicted Net Energy for gain (NEg) of the diet (P = 0.73), from day 28 to 42 there was a linear increase in NEg favoring DCP treatments (P < 0.01), and from day 42 to 56 there was a linear decrease in NEg against the DCP treatments (P < 0.01). At the conclusion of the trial, a subset of heifers (n = 24; 307.89±3.32 kilograms on day 63) were utilized to evaluate blood metabolite concentrations prior to and after a lipopolysaccharide (LPS) challenge. On day 63, heifers were fitted with jugular catheters and moved into individual stalls. On day 64, heifers were challenged intravenously with LPS (0.5 micrograms/kilograms body weight), and blood samples collected every 0.5 hours from -2 to 8 and at 24 hours relative to LPS challenge (0 hour). Serum glucose, blood urea nitrogen (BUN), and non-esterified fatty acid (NEFA) concentrations were determined. Cattle lost less weight at both 24 and 72 hours post-LPS with increasing DCP percentage (P < 0.01). Glucose (P = 0.12) and NEFA (P = 0.13) concentrations did not differ pre-LPS; however, there was a treatment effect for BUN, with elevated concentrations of BUN in CON cattle (P < 0.01). Post-LPS, DCP fed cattle had reduced glucose, elevated NEFA, and reduced BUN concentrations (P = 0.01). Results indicate that dietary DCP modulated metabolite concentrations in heifers following an endotoxin challenge, and affects feedlot performance when incorporated in receiving diets in replacement of corn. Future studies will need to address strategies to increase dry matter intake or explore levels of DCP less than 10% in the diet of newly received heifer calves.