Applied Animal Nutrition-I

Nutritive ratio

 NUTRITIVE VALUE OF FEEDS

1) An indication of nutritive value of a feed is its digestibility of dry matter(%).  Feeds and fodders can be classified as shown below based on their digestibility.

Above 70% = good 

60-70% = moderate 

40-60% = low 

Less than 40% = very low 

2) Nutritive ratio (NR): It is the ratio of the digestible protein to the sum of digestible carbohydrates and fat, the latter being multiplied by 2.25. It is also called albuminoid ratio. It is computed in recognition of the fact that protein serves some special functions in the animal body, which cannot be performed by the digestible nonprotein nutrients present in the TDN. Feeds richer in protein have narrow nutritive ratios while feeds poor in protein content have wide nutritive ratio. It is usual to consider that rations with wide nutritive ratio (1:9) are suitable for idle horses and cattle; a medium ratio (1:6) for early fattening, lactation, working animals, etc. and a narrow ratio (1:0.7) for young stock.

Example 1. Calculate  NR of groundnut cake using the following data :

                                                DCP = 42 ; DEE = 6

                                                DCF=l ; DNFE = 14.5

                                   NR        =  DEE x 2.25 + DNFE + DCF

                                                                 DCP

                                   =           (6 x 2.25) + 14.5 + 1                = 29       =    0.7

                                                                42                                 42

                                                                               

A narrow ratio of 1 : 0.7, since groundnut cake is a protein supplement 

Example 2: Calculate  NR of maize grain:

Maize has 82% TDN and 7% DCP.

            

                NR = TDN - DCP    = 82-7 = 75 = 10.7

                                     DCP      7         7

                A wide nutritive of 1:10.7. It means that for each kg of DCP, maize contains 1.07 kg digestible nonprotein nutrients