Two experiments were conducted. The objective of the first experiment was to determine whether the anatomical location of teats affected colostrum quality. Colostrum composition from the first two, middle three, and last three pairs of teats from 18 sows was determined 1 to 2 h before and 24 h after the birth of the first piglet. Protein, IgG and IgA were significantly reduced (P ≤ 0.05), while lactose and fat tended to be reduced (0.05 ≤ P ≤ 0.1) in posterior teats. Immunoglobulin concentrations decreased (P ≤ 0.05) significantly over time regardless of anatomical location. The objective of the second experiment was to determine how much of the variation in piglet immunoglobulin levels was associated with suckling behaviors when considered in conjunction with sow and piglet birth characteristics. Piglet birth variables and suckling behaviors were recorded for 587 piglets from 43 litters beginning with the birth of the first piglet until 4 h after the sow expelled her placenta. Piglet immunocrits were measured 30 ± 3 h after the onset of farrowing. Ten variables from the multiple regression analysis were identified as sources of variation (P ≤ 0.15) for piglet immunocrits (model R2 = 0.6486) with pigs born alive in the current litter (partial R2 = 0.1596; P = 0.0008) and the anatomical location of the pair of teats suckled most (partial R2=0.1410; P = 0.0001) being the most important. Piglets that suckled the last three pairs of teats had reduced immunocrits (P = 0.01; 0.073 ± 0.003) compared with those that suckled the anterior (0.081 ± 0.002) and middle (0.083 ± 0.003) pairs. Piglets from litters with >16 liveborn had reduced (P ≤ 0.05) immunocrits (0.071 ± 0.002) compared with those from smaller litters (0.079 ± 0.001). The total number of teat pairs suckled (partial R2=0.0615; P = 0.0489), total time observed suckling (partial R2=0.0389; P = 0.0498), average pigs born alive from previous parities (partial R2=0.0889; P = 0.0005), birthweight (partial R2 = 0.0538; P = 0.0497), and time between a piglet's birth and the onset of farrowing (partial R2 = 0.0776; P = 0.0007) were other variables with significant associations with immunocrits. This study demonstrated that suckling behaviors are a significant source of variation for consumption of immunoglobulins and piglets that suckle posterior teats most frequently post-farrowing are at risk for low consumption because of the reduced amount of colostral immunoglobulins produced in those mammary glands.