Variation in Nutrient Content of Microbrewers Grains and Effect on Performance and Carcass Composition When Fed Wet to Growing-Finishing Swine1

Professional Animal Scientist, Aug 2009 by Lynn, B A, Wohlt, J E, Schoknecht, P A, Westendorf, M L

ABSTRACT

The number of microbreweries and brew pubs producing craft beers is increasing. A survey of New Jersey microbrewery establishments was conducted to identify sources, types, and volumes of microbrewers grains (MBG) produced. Almost 1 million kilograms of wet MBG were produced annually in New Jersey. Nutrient content of MBG did not vary with site (brewing facility) or type of brew produced. The CP content of MBG (n = 142) was 25% less than that reported for brewers grains in the NRC or Dairy One Forage Laboratory database sets (20.9 vs. 28% CP; respectively), which may be due to the lower efficiency with which microbrewers remove starch from grains. Using wet MBG to replace 50% of the supplemental protein in a corn- and soybean meal-based diet tended (P = 0.07) to reduce ADG (0.83 vs. 0.92 kg/d) of growing-finishing hogs even though DMI was the same (3.0 kg/d). Brewers grains are low in Lys. Adequate protein and amino acid nutrition is critical in all swine diets for optimal performance.

Key words: microbrewers grain, nutrient content, feed value, swine performance

INTRODUCTION

Large commercial breweries are the major producer and source of wet and dried brewers grains for the US feed industry. However, within the last decade (1985 to 1995) the number of microbreweries and brew pubs producing craft brews has doubled (Modern Brewery Age, 1998; Institute for Brewing Studies, 1999). Spent grains from these smaller brewing facilities, microbrewers grains (MBG), may represent a locally available, inexpensive by-product feed.

Brewers grains, a significant source of protein, fiber, and energy, have long served as a feedstuff for many livestock species (Westendorf and Wohlt, 2002). Nutrient content databases as well as performance studies exist for brewers grains, but not for MBG. Thus, this study was conducted to establish a nutrient content database and feed value of MBG. A survey of New Jersey microbrewing establishments identified sources, types, and volumes of MBG produced. The variation in nutrient content of MBG was evaluated by site (brew pub) and type of brew produced. Feed value of wet MBG was evaluated based on performance and carcass composition when fed to growing-finishing swine.

MATERIALS AND METHODS

Survey of Microbrewers

New Jersey microbrewers and brew pubs were identified by Internet searches (http://www.njbeer.org, http://www.pubcrawler.com, http:// www.yellowpages.com) and listings in the Ale Street News (Maywood, NJ). Phone calls were placed to each establishment to determine whether an in-person survey could be conducted. This technique gave the interviewer flexibility to explain questions and resulted in a higher response rate (Rea and Parker, 1997). Each establishment was assigned a random number between 1 and 31, the preliminary estimated number of microbreweries and brew pubs located in New Jersey. All participants were assured of anonymity at the start of the interview and were referred to subsequently by number only. Each interview lasted 30 to 45 min, and surveys spanned a 9-mo period that commenced December 1998.

Responses to survey questions provided information on grain utilization, types of brew produced, brewing frequency, and disposal of MBG. Total amount of grains used monthly by establishment were summed and reported as that used every 2 mo and annually. Total brew types produced was determined by counting all beer names and styles. Brewing frequency was reported as a range between the least and the greatest number of times a particular brew type was produced per year.

The amount of MBG produced per batch was estimated by the equation: wet MBG = (initial grains � 0.9) (initial grains � 0.9 � 0.57) /0.22, assuming that initial grains contained 90% DM and 57% starch (DM basis) and that wet MBG contained 22% DM (Paul Sirois, Dairy One Forage Laboratory, Ithaca, NY; personal communication). Methods and costs for the disposal of MBG were also recorded.

Collection, Nutrient Analyses, and Comparison of MBG

Three New Jersey microbrew pubs served as sources of MBG: Harvest Moon, New Brunswick; Pizzeria Uno, Metuchen; and J. J. Bitting, Woodbridge. These pubs were chosen because production of brew types was representative of the state microbrewing industry and they were in close proximity to campus. Residual MBG at each pub were collected in 114-L plastic containers for each microbrew (n = 142) produced over a period of 1 yr. Within 6 h of production, each batch of MBG was identified by pub (A, B, and C) and brew type, and a composite sample was collected from all containers. This sample was frozen in a Ziploc plastic bag until analysis.

Samples of wet MBG were dried in a forced-air oven at 60�C and then ground in a Wiley mill (1-mm screen, Arthur H. Thomas, Philadelphia, PA). All samples were then assayed for moisture by oven drying at 100�C (AOAC, 1990), CP by the Kjeldahl procedure (AOAC, 1990), NDF and ADF using sodium sulfate and a-amylase (Van Soest et al., 1991) and the Ankom Fiber Analyzer (Ankom Technology Corp., Fairport, NY), total ash by ignition at 550�C in a muffle furnace for 8 h (AOAC, 1990), Ca, K, Mg, and Na by atomic absorption (Perkin-Elmer, 1971), and P by spectrophotometry (Harris and Popat, 1954).