A slaughter can give you a sweet deal, or a lean animal. How much meat there is to an animal depends on several factors: race and species, selection (for meat, milk, sports, products, eggs...), food (fed on hormones, concentrates), age, carcass composition (high or low fat), slaughter time (winter fat), etc.
Males are usually a lot heavier than females.

The specified kilograms are indicative. I have e.g. already had a turkey of over 20 kilo, but such a beast is not the norm.

Pigeon                 300 to 500 grams ready to cook
Chicken               0.6 to 2 kg
Rabbit                  1.5 to 2 kg (Flemish giant to 6 kg)
Duck                     1.2 to 2.5 kg ready to cook
Goose                  3.5 to 4 kg (normal liver 100 grams, forced to: 600 to 800 grams!)
Turkey                 3 to 5 kg
Goat                     50 kg
Sheep                  90 kg (10% coat)
Pig                         90 kg carcass weight, 56% meat
Cow                      700 kg

Hare                      2.5kg ready to cook
Pheasant            rooster 1.3 kg, 0.9 kg hen, ready to cook
Duck                     300 to 700 grams of ready to cook
Goose                  1 to 2 kg
Partridge             400 grams
Roe                       15-30 buck, goat 13-22, 20 kg ready to cook
Hog                       boar 50-350, 40-300 sow

The consumption of meat decreased in Belgium of 99.9 kg / yr / pp in 2005 by 7.7 kg to 92.2 kg in 2010, mainly due to various meat scandals (dioxin crisis, etc.).

Fasting pigs loose liveweight between 0.12 to 0.20% per hour (most by urine and faeces). Without water even more.

In 9 hours after feed withdrawal carcass weight starts decreasing at 0.1% per hour.

In 24 hours there is a loss of 3.8% of liveweight and 2.1% of carcass weight.

48 hours result in a 7.2% loss in liveweight and a 4.4% loss in carcass weight.