Abstract

This experiment investigated the effects of photoperiod changes on dwarf hamster food and water consumption. Three Roborovski dwarf hamsters were obtained and placed in three separate cages with 10g of food and 120ml of water in each cage. Roborovski dwarf hamsters are small, fast, have a high metabolism, and are active in evening hours. At the start of the experiment, the lighting was controlled by a lamp and a light timer where the amount of light was first increased three hours every three days then decreased three hours every three days. At the end of the experiment, there was an observed increase in amount of  food consumed when the photoperiod increased light and no observed pattern of increase or decrease for water consumed. Although there was an observed increase, there was no significant difference between the amount of consumed food and photoperiods. This result may be due to water leaking, hamster food spilling, and food storage that occurred throughout the experiment. A follow-up experiment will be needed to test if there is a definite relationship between the amounts of food and water consumed compared to photoperiod changes.

Introduction

Found in desert areas with little vegetation, Roborovski dwarf hamsters are able to survive on less water than other dwarf hamsters due to their ability to produce highly concentrated urine. Roborovski dwarf hamsters, scientific name Phodopus roborovskii, are the smallest and fastest of all hamsters. They also have high metabolism and are very active during evening hours (Roborovski Hamsters 2008). In the wild depending on where they live, their diet mainly consists of seeds, plants, and insects (Ross 1994). Since dwarf hamsters are nocturnal in nature, my hypothesis is that when the photoperiod decreases, the hamsters will consume more food and water.

Materials

• 3 Female Roborovski Hamsters
• 3 Hamster Cages
• Econutrition Hamster Food & Water
• Desk Lamp
• Electronic Scale & Measuring Cup
• Light Timer
• Microsoft Excel 2007

Methods

To test the effects of photoperiod changes on P. roborovskii, three female Roborovski dwarf hamsters of same age and weight were obtained and placed in three separate cages. Each cage had 10g of Econutrition hamster food and 120ml of tap water. The experiment lasted about two and a half weeks and all initial amounts of hamster food was pre-measured for the entire experiment. To control the lighting, all three hamsters were placed in a light-controlled room where a desk lamp was centered above them. A light timer was used to automatically control the lighting and was first set for the control time 12 hours of dark and 12 hours of light. On the first day of the experiment, hours of dark started at 9:00p.m. until 9:00 a.m. the following day, while the hours of light started at 9:00a.m. until 9:00p.m. Each day at 9:00p.m., the hamster's food and water was collected and measured then replaced with initial amounts. The control time was repeated for two more days. To allow the hamsters to adjust to the light change, each photoperiod was set for three days. Every three days by changing the light timer, the photoperiod was increased by three hours until the photoperiod reached 6 hours dark and 18 hours light.

To decrease the photoperiod, the same procedure was followed starting at the control time of 12 hours dark and 12 hours light for three days. The hours of light decreased by three hours every three days until the photoperiod reached 18 hours of dark and 6 hours of light.

Results

Data was recorded each day (Table 1 and 2) and at the end of the experiment an ANOVA (analysis of variance) test was performed to see of there was a difference in the measurements or if it occurred out of chance, thus it will explain if the data supports the hypothesis.

Observed results in Table 1 shows an increase in food consumption when the amount of light increased. A p-value of 0.34 for average consumed food (Table 3) indicates no significant difference between photoperiod change and consumed food since it is greater than 0.05. Observed results in Table 2 do not show a significant increase or decrease in water consumption most likely do to frequent water leaks throughout the experiment. A p-value of 0.08 for average consumed water (Table 4) indicates no significant difference between photoperiod and consumed water.

Table 1: Average Food Consumption (g)
Photoperiod	H1	H2	H3
12:12 (Control)	3.8	2.73	2.43
9:15	4.77	2.73	3.94
6:18	4.86	3.25	5.2
12:12 (Control)	2.99	2.34	3.53
15:9	3.68	5.7	6.64
18:6	3.03	3.56	3.55

Table 1: Average food consumption for hamster 1, 2, and 3. The amount of food consumed in the three days of each photoperiod was averaged for each hamster.

Table 2: Average Water Consumption (ml)
Photoperiod	H1	H2	H3
12:12 (Control)	57.5	20	45
9:15	13.7	14.7	16.3
6:18	16	6.67	18.3
12:12 (Control)	21	8	15.3
15:9	37.3	26.7	21.7
18:6	13.3	5.67	35.7

Table 2: Average water consumption for hamster 1, 2, and 3. The amount of water consumed in the three days of each photoperiod was averaged for each hamster.

Table 3: ANOVA Test on Food Consumption
Source of Variation	SS	df	MS	F	P-value	F crit
Rows	12.98958333	5	2.597916667	2.985265	0.066386279	3.325834529
Columns	2.0788	2	1.0394	1.194374	0.342659599	4.102821015
Error	8.702466667	10	0.870246667
Total	23.77085	17

Table 3: A p-value for the columns section represents the variance of consumed food compared to the photoperiods. A p-value of 0.34 shows there is no significant difference between photoperiod change and consumed food since the p-value is much greater than 0.05.

Table 4: ANOVA Test on Water Consumption
Source of Variation	SS	df	MS	F	P-value	F crit
Rows	1752.708511	5	350.5417022	3.900456	0.03195322	3.325834529
Columns	608.8448444	2	304.4224222	3.38729	0.075290767	4.102821015
Error	898.7196889	10	89.87196889
Total	3260.273044	17

Table 4: A p-value for the columns section represents the variance of consumed water compared  to the photoperiods. Since the p-value is 0.08 and greater than 0.05, it shows that there is no significant difference of consumed water compared to the change in photoperiods.

Discussion

Since the p-value of food and water consumption was greater than 0.05, the data did not support my hypothesis. This could be because of invariables that took place throughout the experiment such as frequent water leaking and hamsters spilling and storing food, which would change the results. There are modifications that could be made to improve the experiment such as measuring the food left in the bowls plus the food the hamster stores, purchasing water bottles that are leak-proof, using a 24 hour photoperiod length instead of 18 hours, and performing the experiment over a longer period of time.

References

Microsoft Excel 2007

Roborovski Hamsters: A Site Completely Devoted to Roborovski Hamsters. 2008.

Ross, P.D. 1994. Phodopus roborovskii. Mammalian Species. American Society of Mammalogists. No.459: 1-4.