Methods and lessons in human assisted rearing of addax (Addax nasomaculatus) at Fresno Chaffee Zoo.

Citation

Eschweiler K. 2025. Methods and lessons in human assisted rearing of addax (Addax nasomaculatus) at Fresno Chaffee Zoo. In Treiber K, Brooks M, D’amato-Anderson J, Nylander J, Eds. Proceedings of the Sixteenth Conference on Zoo and Wildlife Nutrition, AZA Nutrition Advisory Group, Oklahoma City, OK.

Abstract

In late February 2025, calf was born to dam who had been under treatment for dental abscess and low body condition since arrival to the institution in late 2024. Female was confirmed pregnant during diagnostic procedure in January 2025. The calf was born early in the morning on habitat and appeared very small and weak. During routine neonate exam of calf within first 24 hours was provided 100mL fresh high-grade colostrum collected from managed herd at Fresno State University via esophageal tube due to no observed feeding by care staff. Calf was returned to mother over night while care staff observed and attempted to syringe feeds of 1:1 colostrum to spring water over night provided at 50 mL per feeding for a total of six feedings within 24 hours. Second neonate exam performed within 48 hours determined no passive transfer; plasma was obtained from second addax female and administered to calf via intraperitoneal transfusion. Post transfusion a nasogastric tube was placed due to no suckling response to syringe feeds. Calf was monitored at hospital for three days and syringe fed through nasogastric tube continued at 50mL per feeding for a total of 300 mL of goat milk split into six feedings within 24-hour period. On the fourth day the calf was moved back to the barn with dam, and on the fifth day the nasogastric tube was pulled but assisted feeds continued to occur. Daily volume was increased by 20% to 60 mL per feeding; however, calf was still not showing suckling response at this time. For the next week, body weight was monitored and feeding ration slowly increased from 8% of BW per 24 hours to 12% of BW per 24 hours divided into 6 feedings. At one week of age, Zoological Milk Matrix 30/52 was added into the goats’ milk at a ratio of 10 g per 100 mL of goat milk. At three weeks of age formula was transitioned from full strength goats’ milk to a 1:1 spring water to goats’ milk with continued 10g of Milk Matrix added per 100 mL of formula. Poly-vi-sol with iron was added in a ratio of 1 drop per 100 mL at this time. Calf weight continued to be monitored daily, and formula ration slowly decreased from 12% BW to 8% BW over the next month. At two months of age, nursing from mother was noted and increasing in frequency. Frequency of assisted feedings decreased over a period of one month until calf no longer needed assisted feeding and confirmed dam provided milk still promoted weight gain. At four months of age calf was fully pulled from assisted feedings and relied solely on dam for feedings.

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