Table 2.

Explanation and descriptive statistics of variables from dairy cattle studies employed when fitting the mixed models

Variables	Explanation of variable as included in the model	Median	SD	Min	Max
Explanatory
Management strategies
Calf suckling	1 if managed to secure milk flow persistency, 0 otherwise	0.0	0.2	0	1
Concentrate supplementation	1 if concentrates are offered, 0 if not	1.0	0.4	0	1
Fodder crops use	1 if fodder crops were used in the feed supply, 0 if not	0.0	0.4	0	1
Improved cattle breeds use	1 if improved dairy breeds were used, 0 if not	1.0	0.3	0	1
Improved feeding	1 if improved quantity and quality feeds were provided, 0 if not	0.0	0.5	0	1
Napier grass use	1 if Napier grass was used as the main forage source, 0 if not	0.0	0.5	0	1
Water management regime	1 if providing water ad libitum, 0 if water provided less frequently	1.0	0.5	0	1
Internal parasite treatment	1 if treating or preventing internal parasites, 0 if not	0.0	0.5	0	1
External parasite treatment	1 if treating or preventing external parasites, 0 if not	0.0	0.5	0	1
Animal
Parity of animal	1 if primiparous, 2 if multiparous and 3 for mixed group of cows	2.0	0.7	1	3
Days in milk (days)	Number of days during lactation that a cow has been milking	10	89.1	1	360
Environmental
Season	1 if winter, 2 if summer and 3 if across seasons	3.0	0.8	1	3
Mean ambient temperature (°C)	Mean daily conditions in study area	23	3.7	14	30
Annual precipitation (mm)	Mean annual rainfall in study area	1048	440.0	75	1290
Altitude (m asl)	Elevation above sea level of study location	1850	770.0	15	2390
Study location	1 if on research station, 0 if on-farm	1	0.4	0	1
Response
Milk yield (kg/day)	Milk yield obtained due to management strategies	6.9	3.1	1.0	14.7
Milk yield SE (kg)		0.3	0.5	0.1	2.7

Min = minimum value; Max = maximum value; asl = above sea level.