Effects of Feeding Crab Processing Waste and Other Protein Supplements on Growth and Ruminal Characteristics of Steers Fed High-Roughage Diets1

Professional Animal Scientist, Oct 2007 by Viswanathan, T V, Fontenot, J P, Baker, S M, Meacham, V

ABSTRACT

A 126-d growth trial was conducted with 48 Angus � Hereford and Angus � Simmental steers (average BW 223 kg). Steers were blocked by body weight and breeding into 8 blocks and randomly allotted within blocks to 6 supplements (8 steers/treatment). Diets were formulated to contain 10.5% CP and 63% TDN, DM basis. The supplements were 1) soybean meal (SBM), control; 2) supplement based on industrial by-products of both plant and animal origin (IPA); 3) experimental supplement based on byproducts of animal origin; 4) hydrolyzed supplement No. 3 (HESA); 5) commercial supplement based on animal protein, Pro-Lak; and 6) crab meal. In each diet, one-third of the N was supplied by the protein supplement. Steers were full fed in individual stalls during a 16-h period daily. Lower (P

Key words: crab waste, feed efficiency, protein supplement, steer, volatile fatty acid

INTRODUCTION

Quantity of microbial protein synthesized in the rumen can be inadequate for rapidly growing steers (Chalupa, 1975) or high-producing dairy cows (Santos et al., 1984). Feeding diets supplemented with protein sources that will degrade slowly in the rumen have improved N and amino acid flows to the small intestine (Santos et al., 1984; Ludden and Cecava, 1995).

Crab processing waste, a by-product obtained from the seafood industry, can be fed either as a dehydrated meal (Patton et al., 1975; Velez et al., 1991) or by ensiling with roughage (Samuels et al., 1991, 1992). Abazinge et al. (1994) suggested a lower rate of ruminal degradation, deamination, or both, for acetic acid-treated crab waste silage, which reflects its potential as a source of undegradable intake protein.

The objective of this study was to evaluate crab processing waste and other protein supplements on growth, feed efficiency, and ruminal and blood parameters in steers.

EXPERIMENTAL PROCEDURES

Forty-eight Angus � Hereford and Angus x Simmental steers (average BW 233 kg) were blocked by weight and breeding into 8 blocks and were randomly allotted within blocks to 6 diets containing the following protein supplements: 1) soybean meal (SBM), control; 2) supplement based on industrial byproducts of both plant and animal origin (IPA); 3) experimental supplement based on byproducts of animal origin (ESA); 4) hydrolyzed supplement No. 3 (HESA); 5) commercial supplement based on animal protein (CS), ProLak (H. J. Baker and Bro. Inc., Stamford, CT), and 6) crab meal (CM).

The HESA was processed in a high intensity mixer and hydrolyzed under basic conditions at 110�C at atmospheric pressure for approximately 10 min (after all ingredients had been incorporated in the supplement). Protein supplements IPA, ESA, and HESA were obtained from Harmony Products Inc. Chespeake, Virginia. Crab meal was obtained from Graham and Rollins, Hampton, Virginia. The mixed protein supplements, IPA, ESA, and HESA were formulated as shown in Table 1. The other dietary ingredients were orchard grass (Dactylus glomerata L.) hay, cottonseed hulls, corn grain, and mineral and vitamin supplements.

The chemical composition of protein supplements and other ingredients are presented in Table 2. Crab meal contained an average of 15.7% chitin, DM basis. Because ADF is a measure of chitin (Ayangbile, 1989), chitin content in CM is the value obtained for ADF content. It has been reported that chitin contains 6.9% N (Black and Schwartz, 1950). Thus, nonchitin CP of CM was calculated to be 31.6%.

Diets were formulated to contain 10.5% CP and 63% TON, DM basis (Table 3). In each diet, one-third of the N was supplied by the protein supplement. Diets were formulated to meet or exceed NRC (1996) requirements. Diet formulation was adjusted periodically based on the chemical composition of ingredients and the mixed diets. At every mixing of diets, samples of hay, protein supplements, other feed ingredients, and diets were collected. These samples were ground through a 1-mm-mesh screen in a mill (Thomas-Wiley, Laboratory Mill, Model 4, Arthur H. Thomas Co., Philadelphia, PA). Samples were analyzed for DM and CP by AOAC (1990) procedures. Calcium was measured by atomic absorption spectrophotometer (Perkin Elmer 5100, Norwalk, CT) and P by the colorimetric method of Fiske and Subbarow (1925) after wet ashing (Sandel, 1959). Diet samples were also analyzed for NDF, ADF (Van Soest and Wine, 1967), lignin, cellulose, hemicellulose (Van Soest and Wine, 1968), and ash (AOAC, 1990).

All steers were dewormed with Ivomec (1 mL/50 kg BW, s.c.; Merck & Co. Inc., Rahway, NJ) before the trial began. Initial and final weights were averages of 2 consecutive daily weights taken 16 h after removal from water. Steers were allowed feed in individual stalls (full fed) during a 16-h period daily.

Animals were weighed every 14 d. Ruminal fluid and blood samples were collected at 56 d and at the end of the trial (126 d). Ruminal liquor was collected from each steer using a stomach tube with suction by a vacuum pump and filtered through 8 layers of cheesecloth, and pH of the fluid was measured immediately after the collection (Accumet, Mini pH Meter, Model 640 A, Fisher Scientific Co., Pittsburgh, PA). Samples for the determination of VFA and NH^sub 3^ N were taken in 15-mL tubes containing 1 mL of 25% metaphosphoric acid and 1 drop of concentrated H2SO4, respectively. Samples were centrifuged at 1,800 x g for 15 min. Vola tile fatty acids were determined by gas chromatography (Vista 6000 gas chromatograph, Varian, Palo Alto, CA). A glass column packed with 10% SP-1200:10% H^sub 3^PO^sub 4^ liquid phase on 80/100 chromosorb WAW packing (Supelco Inc., Belfontaine, PA) was used to separate acetic, propionic, butyric, valeric, isobutyric, and isovaleric acids. The detector temperature was 175�C, the column temperature was 125�C, and the inlet temperature was 180�C. The VFA concentrations were determined by integration using a VFA standard containing acetic (51.66 �mol/mL), propionic (30.63 �mol/mL), butyric (10.4 �mol/mL), valeric (5.18 �mol/mL), isobutyric (4.96 �mol/mL), and isovaleric (4.95 �mol/mL) acids. Ruminal NH^sub 3^ N was determined by the method described by Beecher and Whitten (1970).