Effect of level of fish meal on intake and performance in calves grazing sorghum

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references.Effect of five concentrations of fish meal (FM 0, 9, 27, 45 and 630-. of DM) in .91 kg/d of a supplement was evaluated in thirty-five Brahman-European cross calves (avg BW=160 + 20 kg). Supplements were formulated with rice mill feed, molasses, and FM to have equal concentration of calcium, phosphorus and adequate trace minerals. All animals rotationally grazed successive 1.25 ha strips of sorghum pasture for 62 days. Animals were individually penned for 45 min/d and offered their assigned supplement. Two markers (samarium and ytterbium nitrate) were used to estimate individual fecal output (FO) and indigestible neutral detergent fiber content of feces and esophageal masticate was used to estimate digestibility. Esophageal masticate of four cannulated steers contained 12. 60-. crude protein, 7 7 . 3 O-. neutral detergent fiber (NDF) and 25-. indigestible NDF. The FO (g/kg BW) and forage organic matter intake were positively .07 respectively) related (P .80) . The relationship between SIP and FCP (FCP = .61 + .63 SIP) indicated that 63% of SIP was truly undigested if metabolic fecal crude protein (MFCP) was constant at .61 g/kg BW. Regression of apparently digested intake protein (g/kg OMI) vs intake protein (IP, g/kg OMI), yielded a poor fit. A model of constant slopes (true digestibility) and multiple intercepts (MFCP) appeared appropriate. Fitting the data to such a model yielded estimates of slope of .92 (SE = .18) with intercepts varying from-11 to-52 g/kg OMI. The relationship between MFCP so estimated and mean total intake protein (TIP) by level of SIP was : MFCP =-39.18 + .79 TIP. Thus, in this experiment, each unit increase in TIP was associated with an increased loss of .79 units of MFCP. Possible biological reasons for this relations between TIP and MFCP are discussed