The lack of information about seasonal variation of seminal plasma proteins in goats from Northeast Brazil led us to investigate the protein band distribution throughout the year. The experiment lasted one year (from April 2006 to March 2007) in which 230 semen collections from five adult goats (Capra hircus) were carried out, at ages ranging from 18 to 22 months, weighing 42.0 ± 10.0 kg, belonging to Anglo Nubian breed. A pool of seminal plasma samples from all the animals in each month of the year was submitted to 1D electrophoresis SDS-PAGE, 12.5%. The gels were analyzed through Life Science Software from UVP, Inc®. The correlation between air humidity and total seminal plasma proteins was not significant (r = -0.24; P > 0.05), while a moderate and significant correlation was found between temperature and total protein (r = 0.39; P < 0.001). The semen volume and concentration showed statistical difference (P < 0.05) between months throughout the year, while the motility and vigor did not (P > 0.05). The analyzed gels showed a high frequency of molecular mass bands below 50 kDa throughout the year, followed by protein bands from 50 to 100 kDa. The major numbers of bands occurred in October and November, while May was the month that presented a smaller number of protein bands. The molecular bands of 14, 22, 24, 40, 55 and 66 kDa were present in all the months of the year. The band of 16 kDa was found in 41.7% of the months. May was the only month that did not show the 30 kDa. August and September did not present the bands of 34 and 35 kDa, while October showed both bands. The 45 kDa band was found in 75% of the months, being present in January, May, July, September and November. The 46 kDa band was identified in June and August, while the 47 kDa was identified in April. The 70 kDa band was identified from May to November (58.3%), the 72 kDa band was found in January, March and April (25%) and bands of 92 to 97 kDa were found from April to December (75%). These results showed a band distribution variation throughout the year in the Anglo Nubian goat breed in the semi-arid area of Brazil. It is concluded that medium rainfall or water scarcity in the dryer months seems to promote variation in semen volume and concentration and total protein distribution throughout the year. As no month variation was observed in semen motility and vigor, and protein bands probably related to fertility showed an uniform distribution throughout the year, it is suggested that there is no fertility variation during the year in Anglo-Nubian goats the semi-arid region.
