title: Effects of a dietary mixture of meat and bone meal, feather meal, blood meal, and fish meal on nitrogen utilization in finishing Holstein steers.
abstract: Our objective was to determine to what extent rate and efficiency of protein gain in finishing cattle can be enhanced by feeding an amino acid-balanced mixture of undegraded intake proteins. The Cornell Net Carbohydrate and Protein System (CNCPS) model was used to formulate a corn-based diet that would meet the rumen requirements for 410-kg large-framed steers with an estrogen implant and fed an ionophore. The CNCPS model was also used to formulate a highly undegradable intake protein (UIP) mixture from meat and bone meal, blood meal, fish meal, and hydrolyzed feather meal to provide the amino acids needed to supplement those derived from microbial protein to better meet amino acid requirements for growth. Four Holstein steers weighing 407 kg were offered a 90:10 concentrate-forage diet at hourly intervals at 95% of ad libitum intake. The steers were injected with 500 microg of estradiol-17beta at 12-h intervals to mimic the effects of an estrogenic implant. Treatments planned consisted of inclusion of the UIP mixture at 0, 2.5, 5, and 7.5% of the diet DM. Dry matter intake was fixed at 6.4 kg/d, and DM digestibility was not significantly affected by varying the amount of UIP addition. Apparent digestibility of N increased (P = .011) from 63.8 to 65.8, 70.7, and 71.5%, the amount of N absorbed increased (P = .001) from 73 to 84, 100, and 106 g/d, and N balance increased (P = .003) from 20 to 30, 33, and 39 g/d when UIP was fed at 0, 2.6, 5.2, and 7.8% of diet DM, respectively. The efficiency of N use increased 39.7%, and biological value increased 31.6% when the UIP mixture was added to the diet. Circulating concentrations of plasma urea N (PUN) were increased (P = .017) from 4.5 for the control diet to 5.7, 6.2, and 6.1 mg/dL when the UIP mixture was added at 2.6, 5.2, and 7.8%, respectively. Corresponding IGF-I concentrations were also increased from 491 to 558 and 624 ng/mL with 2.6 and 5.2% levels of UIP addition. Plasma glucose, NEFA, and insulin concentrations were not affected by feeding the UIP mix. The rate and efficiency of N use for growth improved with addition of an amino acid-balanced UIP mixture to the diet.
authors.affiliation: Department of Animal Science, University of Agriculture, Forestry and Renewable Natural Resources, Vienna, Austria.
authors.forename: W F
authors.initials: WF
authors.lastname: Knaus
authors.forename: D H
authors.initials: DH
authors.lastname: Beermann
authors.forename: T F
authors.initials: TF
authors.lastname: Robinson
authors.forename: D G
authors.initials: DG
authors.lastname: Fox
authors.forename: K D
authors.initials: KD
authors.lastname: Finnerty
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000821:Animal Feed / Q000032:analysis* / Q000592:standards; D000818:Animals; D001688:Biological Products; D001769:Blood; D001806:Blood Urea Nitrogen; D001842:Bone and Bones; D002417:Cattle / Q000378:metabolism*; D004032:Diet / Q000662:veterinary*; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism; D004063:Digestion; D005241:Feathers; D005396:Fish Products; D008297:Male; D008460:Meat; D008903:Minerals; D009584:Nitrogen / Q000378:metabolism*; D006109:Poaceae; D013025:Glycine max; D003313:Zea mays
chemical_list: D000596:Amino Acids; D001688:Biological Products; D004044:Dietary Proteins; D008903:Minerals; D009584:Nitrogen; C027762:bone meal