MSTN and hydrops fetalis: We genotyped (i) 301 “modern” BBC, (ii) 28 “old” BBC (all homozygous for the p.D273RfsX13 MSTN mutation), (iii) 52 animals from the dual-purpose BBM subpopulation, and (iv) 191 Dutch HF sires, with the Illumina BovineHD array interrogating >700 K single nucleotide polymorphisms (SNP) dispersed across the genome.