My first sighting of this year's new born kits was when I saw their mother swimming with one of them in her mouth to an area nearby where their father was waiting to greet them.
Litter size (number of kits born in total and live born kits) and litter weight (weight in g of the kits born in total and live born kits) were monitored at birth.
However, the number of live born kits was smaller under constrained conditions compared to normal conditions (−3.4 kits per parturition).
However, although the individual weights of V36 kits at birth were similar under NF and NC environments, they were significantly smaller under the HC environment (−6.0 and −6.5 g for total kits born and live born kits, respectively; P <0.05).
There were no statistically significant differences between the lines (the pooled standard error of means was 0.57 for total number of kits born and 0.68 for number of live born kits).
At first parturition, LP, V16 and V36 females had on average a total number of kits born equal to 9.3, 9.5 and 10.3, respectively, with 8.6, 8.4 and 9.3 live born kits, respectively.
In contrast, under the HC and NF environments, V36 females were more able to maintain the total number of kits born (−2.0 and −1.4 kits per parturition under HC and NF, respectively; P = 0.35) than the number of live born kits (−3.4 kits per parturition; P = 0.003 and −2.1 kits per parturition; P = 0.24 under HC and NF, respectively).
Under the HC and NF environments, V16 females had a much lower total number of kits born (−2.6 and −3.2 kits per parturition under HC and NF, respectively; P <0.01) compared to the NC environment but the decrease in number of live born kits was less pronounced (−1.6 and −1.7 kits per parturition under HC and NF, respectively; P = 0.67).
Finally, energy content of the litter was calculated as the total weight of stillborn and live born kits in the second and third parturitions assuming 3.4 MJ per kg of kits produced [ 39].
García and Baselga [ 8] already reported an increased number of live born kits in response to selection for line V, and Quevedo et al. [ 43] observed a greater efficiency of DE use for foetal growth.
