As humans we can imagine what is wrong about withholding freedom from other people. When a child is born, birth is the first step on the way to freedom. His upbringing will hopefully prepare him to function freely as an adult later in life. Freedom is a means and an end to a meaningful life. But every individual has to determine for himself what is meaningful.
Animals in factory farming are born to be eaten when they are barely mature, or to produce food for a certain period of time.
In cases where animals are kept to be eaten, the time they are kept will be as short as possible. A longer life is economically not feasible. The most familiar and most widespread examples are meat pigs and chicks. These animals are given the least opportunity to behave naturally, and are only fed in a way that they will grow as quickly as possible. Their short lives consist of boredom because they are waiting mainly in the dark to keep them calm (low energy). Eating and sleeping are almost their only activities. At the moment of slaughter, they are unprepared to anything unusual and so it is a stressful event. More so if they are transported over long distances to the slaughterhouse. In the first stage of their lives they feel too little and in the final stages they feel too much.

 

Is this wrong: having an animal grow up disabled, so to speak, for meat consumption? Is condemning them to boredom reprehensible towards the animals and harmful to their well-being? Is it a form of abuse when you do not optimize their welfare? Is an animal's life meaningful when it only lives to be eaten and not for itself?

Is there an answer that can convince a person who is indifferent to the rights of an animal?

When we see other people suffer, we can try to place ourselves in that other person's shoes and try to imagine how this would feel. Most of us will then try to help this other person and to relieve their suffering.
Man has only recently invented the situation of withholding every sort of freedom from animals even before they are eaten. Before that time, the animals could at least enjoy their freedom before they were eaten.
We can now help animals in factory farming by freeing ourselves: by not eating meat from factory farming and by making it impossible to make money on the exploitation and exportation of animals. This alone does not make life more meaningful, but at least there is less pointlessness and suffering.