Effect of the gestation and lactation on fiber diameter and its variability in Peruvian alpacas

A study was conducted to know the influence of the pregnancy and lactation states on the fiber performance in alpacas at Pacomarca experimental farm in the Peruvian highlands. Records obtained from the regular performance recording software of the farm were used, gathering 8648 records of 1541 females and 366 males of Huacaya ecotype, and 2410 records of 374 females and 132 males of Suri ecotype, registered from 2001 to 2015 and belonging to animals of three or more years. A mixed linear model for fiber diameter, standard deviation and coefficient of variation fitted the physiological state with five categories (milking, pregnant, milking and pregnant, open females and males) as an effect jointly with others such as year of recording, age from 3 to 9 or more years old and coat color. Huacaya and Suri ecotypes were independently analyzed. All the effects included in the model appeared as highly significant, being the paired differences less significant in Suri because of the lower number of records. Lactation physiological state appeared as an important effect affecting fiber performance, explaining a difference of 1.2 and 1.0 µm of differences in respectively Huacaya and Suri pregnant females, while pregnancy appeared with a much less relevant influence. Other factors greatly influenced the fiber diameter. Thus, age had a very important effect increasing 3.71 µm from 3 to 9 years of age in huacaya and 4.52 µm en Suri. A difference of 3.09 µm in huacaya and 5.93 µm in Suri was found between dark and white coat colored alpacas. These results recommend modifying the genetic evaluation model by fitting the physiological state of females to increase the accuracy of the breeding values used to select animals in the breeding scheme of the farm.