Nutritional qualities of agro-industrial by-products and local supplementary feeds for dairy cattle feeding

Abstract

This study assessed the nutritional qualities of major agro-industrial by-products (AIBPs) and locally available feed resources commonly used as supplementary feeds to dairy cattle in Ethiopia. A total of 58 samples belonging to five categories of supplementary feeds viz., compound dairy rations/concentrates, oilseed cakes, wheat bran, middling and grains, brewery by-products, and pulse grain by-products collected from different agro-industries located in and around Addis Ababa and local sources were included in the study. The feed samples were analyzed for chemical contents (DM, Ash, CP, NDF, ADF, Lignin, and in-vitro organic matter digestibility (IVOMD) at Holetta Agricultural Research Center Animal nutrition laboratory. Contents of the various nutritional parameters showed significant variations (p<0.05) among sub-groups within the different categories of supplementary feeds. The important nutritional parameter, CP content, was higher in calf ration among the compound dairy feeds, in cotton seed cake among the oilseed cakes, in wheat middling among the cereal grain by-products, in industrial brewery residue among the brewery byproducts, and in mixed pulses screenings among the pulse grain by-products. The result also revealed considerable differences among the different categories of supplementary feeds in average values of the important nutritional parameters. Accordingly, the average CP content varied in the order: oilseed cakes (310.4g/kg DM)>brewery by-products>compound dairy ration>pulse grain by-products>cereal grain by-products (139.2g/kg DM). The mean NDF content varied in the order: brewery by-products (577.7g/kg DM)>pulse grain byproducts> compound dairy ration>oilseed cakes>cereal grain by-products (250.2g/kg DM). The average ADF content varied in the order: pulse grain by-products (327.8g/kg DM)>brewery by-products>oilseed cakes>compound dairy ration>cereal grain by-products (92.0g/kg DM). The average lignin content also varied in the order: oilseed cakes (79.5g/kg DM)>brewery by-products>pulse grain by-products>compound dairy ration>cereal grain by-products (20.9g/kg DM). The mean IVOMD varied in the order: cereal grain by-products (763.3g/kg DM)>compound dairy ration>oilseed cakes>brewery by-products>pulse grain by-products (537.5g/kg DM). It was generally observed that oilseed cakes and brewery byproducts had higher, while cereal grain by-products and pulse grain by-products had lower CP contents than the range (17-19%) recommended by NRC in the rations of lactating dairy cows during the early lactation stage. On the other hand, the average CP content recorded in compound dairy rations was comparable with the NRC recommendations in dairy cattle diets.