Rapid growth of Nile crocodile (Crocodylus niloticus) hatchlings on farms shortens the
time to slaughter for skins, thus reducing costs and improving farm efficiency. The aims
with the project were to assess the utility of various egg attributes (length, width, volume,
mass and density) as predictors of hatchling mass (HMinitial) for 269 eggs from 15 clutches
and to assess these egg attributes, HMinitial and egg productivity as predictors of the mass
of the hatchlings 68–75 days after hatching (HMend). Hatchlings heavier than 61,5 g were
individually marked and assigned to five pens according to HMinitial until the HMend of 129
hatchlings was determined. Strong and meaningful positive, linear relationships existed
between HMinitial and all egg attributes except egg density, where the relationship was
strong and negative (P < 0,001). HMend varied widely across as well as within clutches. It is
most compatible with the data that HMinitial (P = 0,08) and egg productivity (P = 0,02) have
meaningful negative relationships with HMend when all five pens are included in the model.
Considering pens separately, the direction of the relationship between HMinitial and HMend
was negative for three pens and neutral for two. The direction of the relationship between
egg productivity and HMend was negative for four pens and positive for one. The models
that each included one predictor as well as pen only explained 8–14% of the variation in
HMend, suggesting that factors other than those studied largely affected growth.
Nylkrokodilbroeilinge (Crocodylus niloticus-broeilinge) wat
vinniger groei op plase kan vroeër geslag word vir hulle velle, wat koste verminder en
plaasdoeltreffendheid verhoog. Die projek se doel was om die nut van verskeie eierattribute
(lengte, wydte, volume, massa en digtheid) as voorspellers van broeilingmassa (BMbegin) vir
269 eiers van 15 broeisels te bepaal, en om hierdie eierattribute, BMbegin en eierproduktiwiteit
as voorspellers van die massa van die broeilinge 68–75 dae ná uitbroeiing (BMeinde) te
beoordeel. Broeilinge swaarder as 61,5 g is individueel gemerk en volgens BMbegin aan
vyf hokke toegewys, totdat die BMeinde van 129 broeilinge bepaal is. Sterk, betekenisvolle,
positiewe, lineêre verbande bestaan tussen BMbegin en al die eierattribute behalwe
eierdigtheid, waar die verband sterk en negatief was (P < 0,001). BMeinde het baie tussen en
binne broeisels gevarieer. Dit is die beste versoenbaar met die data dat BMbegin (P = 0,08) en
eierproduktiwiteit (P = 0,02) betekenisvolle negatiewe verbande met BMeinde het wanneer al
vyf hokke by die model ingesluit is. Vir hokke wat afsonderlik beoordeel is, was die rigting
van die verband tussen BMbegin en BMeinde negatief vir drie hokke en neutraal vir twee. Die
rigting van die verband tussen eierproduktiwiteit en BMeinde was negatief vir vier hokke
en positief vir een. Die modelle wat elk slegs een voorspeller en hok as koveranderlike
ingesluit het, verklaar 8–14% van die variansie in BMeinde, wat aandui dat ander faktore as
dié wat bestudeer is groei grootliks beïnvloed.
