Final answer:
It is false that a cow's net energy requirements are greater during pregnancy than milking. The energy requirements during lactation are higher due to the energy-intensive process of milk production, compared to the additional but lesser energy demands of sustaining pregnancy.
Step-by-step explanation:
The statement is false. A cow's net energy (NE) requirements are generally higher during lactation rather than during pregnancy. This is because the process of lactation involves the production of milk, which is a highly energy-intensive process requiring additional glucose for production of lactose, formation of milk fat, and synthesis of milk protein casein. The energy cost of lactation is such that for the production of 80 kcal of milk, a mother must expend 100 kcal. In contrast, while a pregnant cow does require more energy than when not pregnant, particularly in the latter stages to support the development of the foetus and to cope with the increased metabolic demands, this does not typically surpass the energy demands of producing milk during lactation.