Hormonal induced lactation in transgenic goats

The aim of this study was to hormonally induce lactation in prepubertal, nu lliparous, and male goats both transgenic and non-transgenic. Analysis of m ilk quality, recombinant protein expression levels, total amount of recombi nant protein produced, and the affect on long-term reproductive capability was assessed. Fifty-one goats (Saanen, Alpine, and Toggenburg), male and no n-pregnant females, 2-31 months of age, either non-transgenic or transgenic were evaluated with a total of 10 transgenes (constructs) represented. Ani mals were given estradiol (0.25 mg/kg, IM) and progesterone (0.75 mg/kg, IM ) on days 1, 3, 5, 7, 9, 11 and 13, while prednisilone (0.4 mg/kg, IM) was administered on days 14-16 with mammary massage occurring daily from day 5 onward. Forty of 51 animals, (36 of 38 females and 4 of 13 males) produced milk with total volumes in the 30-day experiment, ranging from 20 mu l to 5 30 mis per day, or approximately 500 mu l to 6.8 liters total. Milk composi tion was analyzed for various parameters (total protein, fat content, total solids and somatic cell count) with no significant differences found betwe en induced and natural milk. Expression levels of recombinant proteins from transgenic animals that were analyzed during the induced lactation, and su bsequently during normal lactations, were found to have no significant diff erences. Total amount of recombinant protein produced was evaluated at diff erent expression levels with no statistical significance seen. While over 9 0% of the females placed in the regimen became pregnant, there was a correl ation between increased age at time of induction and an increase in number of breedings, or reproductive cycles needed to establish a pregnancy after induction. For males, 100% placed in the regimen settled females after horm onal induction of lactation. Semen quality was evaluated prior to, during, and after hormonal treatments. Semen volume and sperm number did not differ ; however, for a small percentage of males, there was a decrease in sperm a nd post thaw motility after hormonal treatments. These levels returned to n ormal within 4-5 weeks. Subsequent natural lactations showed total milk vol umes within breed standards. These findings indicate that hormonal inductio n of lactation in the caprine species is a viable alternative to pregnancy for initiating lactation and milk production, does not adversely impact rep roductive performance long-term, and can benefit the early assessment of re combinant proteins produced in a transgenic founder program.