Milk Collection Methods for Mice and Reeves' Muntjac Deer

Summary

Milk collection from animal models facilitates various research avenues: understanding passive immunity, identifying pathogens responsible for vertical transmission and, through the use of transgenic mice, even commercial production of proteins found in human breast milk. Here we illustrate a simple method for milk collection in mice and Reeves’ muntjac deer.

Abstract

Animal models are commonly used throughout research laboratories to accomplish what would normally be considered impractical in a pathogen’s native host. Milk collection from animals allows scientists the opportunity to study many aspects of reproduction including vertical transmission, passive immunity, mammary gland biology, and lactation. Obtaining adequate volumes of milk for these studies is a challenging task, especially from small animal models. Here we illustrate an inexpensive and facile method for milk collection in mice and Reeves’ muntjac deer that does not require specialized equipment or extensive training. This particular method requires two researchers: one to express the milk and to stabilize the animal, and one to collect the milk in an appropriate container from either a Muntjac or mouse model. The mouse model also requires the use of a P-200 pipetman and corresponding pipette tips. While this method is low cost and relatively easy to perform, researchers should be advised that anesthetizing the animal is required for optimal milk collection.

Introduction

Animal models provide insight into disease pathology that cannot be gained by in vitro analysis. To provide the most efficacious results, it is important to use an animal model that is closely related to the disease and species of interest. For example, the Reeves’ muntjac (Muntiacus reevesi), a small Asian deer^1,2, and transgenic mice expressing the cervid prion protein (CerTgPrP)³ are useful animal models for cervid species. Both species are polyestrous, allowing year-round breeding, and therefore a consistent source for pregnancy-related tissues and fluids to study specific mechanisms in cervid biology. Studies of milk ....

Protocol

1. Mouse Milking Protocol

The methods described in this protocol were approved by IACUC.

1. Separation of the Dam from Offspring

1. Select the dam to be milked. Choose a dam with a litter of 4 or more pups that is 8-12 days post parturition to provide maximal milk collection—although collection is possible at any time point post parturition up to 21 days.
2. Separate the dam from her litter at least 2 hr before milking.
   Note: Should one desire to milk more than one dam in a given time period, it is acceptable to house the separated dams in the same cage with adequate food and water suppl....

Results

Mouse

From our experiments, we have determined that it is possible to collect approximately 100-400 μl of milk from one laboratory mouse, dependent on several variables. These variables include 1) the amount of time set aside for collection, 2) the dose of oxytocin administered, 3) how many pups the dam is currently nursing and 4) the amount of time post parturition. Our studies have shown that the highest yield is obtained when the dams are separated from their offspring for .......

Discussion

Mouse

There are several factors to take into consideration when collecting milk from a mouse, including 1) the amount of time set aside for collection, 2) the dose of oxytocin administered, 3) how many pups the dam is currently nursing and 4) the amount of time that has passed since parturition at the time of collection. Using previous studies as guidelines, we set out to optimize conditions for milk yield.

Previous research has directly correlated .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Materials—Mouse
Ketamine (KetaVed 100 mg/ml) (dose: 80-100 mg/kg)	MWI/Vedco	011075
Xylazine (TranquiVed 100 mg/ml) (dose: 5-10 mg/kg)	MWI/Vedco	NADA 139236
Eye lubricant	MWI/Apexa	701013
Oxytocin (2 IU/kg)	Vet One	501013
Materials—Muntjac
Midazolam (1-2 mg/kg)	Amerisource Bergen Drug Corp	924326	Optional: researcher can either use Midazolam on its own or BAM combination as an anesthetic
Butorphanol tartrate (Torbugesic) (0.45 mg/kg)	Fort Dodge Animal Health	NADA 135-780
Azaperone tartrate (0.25 mg/kg)	ZooPharm
Medetomadine HCl (0.07 mg/kg)	ZooPharm
Antipamezol hydrochloride (Antisedan) (dose: 0.25 mg/kg)	Orion Corporation	NADA 141-033
Oxytocin (10 IU/kg)	Vet One	501013
Equipment—Mouse
P-200 Pipetman	Gilson	F123601
200 μl pipette tips	Light Labs	B-2004-SH
1 ml syringes	MWI	005427
27 G needles	MWI	002031
Equipment—Muntjac
15 ml conical tubes	VWR	21008-918
22 G needles	MWI	873
3 ml luer lock syringes	MWI	001377