God made His covenant with Abraham through the crucified and resurrected Christ. The three kinds of slain cattle here signify Christ in His humanity being crucified for us, and the two living birds signify Christ in His divinity being the living, resurrected One (John 11:25; Rev. 1:18). Christ was killed in His humanity, but He lives in His divinity (John 14:19; 1 Pet. 3:18 and note 1 Pet. 3:183).
The heifer was for a peace offering (Lev. 3:1), the female goat was for a sin offering (Lev. 4:28; 5:6), and the ram was for a burnt offering (Lev. 1:10). That they were all three years old signifies that Christ was offered to God and was crucified in resurrection (John 2:19; 11:25; Heb. 9:14).
In typology, the turtledove signifies a suffering life, and the young pigeon signifies a believing life, a life of faith. These are two characteristics of the Lord’s life on the earth. Since two is the number of testimony (Matt. 18:16; 2 Cor. 13:1), the two living birds bear testimony of Christ as the resurrected One living in us and for us (John 14:19-20; Gal. 2:20).
Five is the number of responsibility (see note Matt. 25:21a). Hence, the fact that there were three cattle and two birds, making a total of five items, signifies that Christ as the crucified and living One is now bearing all the responsibility for the fulfillment of God’s eternal purpose.