data set of live calves. The models included embryo treatment, sex of calf and farm-

season. All values are reported as least-squares means SEM. The proportion of calves

that were male was analyzed among all calves and all live calves using the LOGISTIC

procedure of SAS. The model included season of transfer, embryo treatment, farm-

season and all two-way interactions. The effect of breeding type (i.e., artificial

insemination or embryo transfer) on calf birth weight and calf sex for a subset of cows at

Farm 2 was also analyzed. In addition, chi-square analysis was used to determine if the

sex ratio of all calves and all live calves deviated from the expected 50:50 ratio.

 Results

Embryo Development

 Overall, there was no effect of IGF-1 on cleavage rate at day 3 after insemination

(control 77.3 0.8% vs. IGF-1 78.9 0.8%), the proportion of oocytes that became

blastocysts (control 16.2 1.3% vs. IGF-1 17.2 1.3%), or the proportion of oocytes

that became advanced blastocyst stages (expanded, hatching or hatched) (7.6 0.7% vs.

IGF-1 8.4 0.7%). When only those replicates in which blastocyst development was

recorded on day 8 after insemination (n = 7 replicates) were analyzed separately, there

was also no effect of IGF-1 on the proportion of oocytes becoming blastocysts (control -

21.9 1.6% vs. IGF-1 20.2 1.6%) or advanced blastocysts (control 8.9 0.4% vs.

IGF-1 8.8 0.4%). However, among replicates in which blastocyst development was

recorded on day 7 after insemination (n = 15 replicates), IGF-1 increased the proportion

of oocytes becoming blastocysts (P < 0.001; control 13.9 0.4% vs. IGF-1 16.0 +

0.4%) and tended to increase the proportion that became advanced blastocysts (P < 0.07;

control 7.1 0.4% vs. IGF-1 8.2 0.4%).