Table 1.
Resource input or waste output per kilogram of milk* | Change per unit of milk with rbST use†, % | |
---|---|---|
Resource inputs | ||
Net energy for maintenance, MJ | 1.73 | −11.8 |
Metabolizable protein for maintenance, g | 30.4 | −7.5 |
Total net energy requirement‡, MJ | 4.79 | −4.5 |
Total metabolizable protein requirement‡, g | 77.6 | −3.2 |
Feedstuffs per kg dry matter | 0.82 | −8.1 |
Waste outputs | ||
Methane, g | 26.2 | −7.3 |
Manure, kilogram freshweight | 1.92 | −6.8 |
N excretion, g | 5.67 | −9.1 |
P excretion, g | 2.98 | −11.8 |
*Based on the average annual milk yield (28.9 kg/d) for 2006.
†Use of rbST significantly increases milk production (7); yield response to supplementation equaled 4.5 kg per day.
‡Comprises nutrients required for maintenance plus lactation.