Selenium Sources in the Diet of Dairy Cows and Their Effects on Milk Production and Quality, on Udder Health and on Physiological Indicators of Heat Stress

Figures & data

Figure 1. Number of mammary quarters by level of subclinical mastitis (CMT) in the inorganic and organic selenium treatments.

Table 1. Ingredients and chemical composition of the experimental diets.

	Diet
Ingredients, %
Corn silage	53.6
Triturated corn	18.4
Soybean meal	6.0
Whole cotton seed	10.8
Protein-mineral premix^°	11.2
Nutrients
Crude protein, %DM	17.55
Ether extract, %DM	4.70
Mineral matter, %DM	7.78
Neutral detergent fibre, %DM	38.87
Acid detergent fibre, %DM	24.94
Metabolisable energy, Mcal/gDM	2.82

°Product composition: dry matter, 92%; crude protein, 40%; metabolisable energy, 2.82 Mcal/kg; ether extract, 1.8%; calcium, 45 g/kg; phosphorus, 14 g/kg; magnesium, 10 g/kg; potassium, 10 g/kg; sodium, 16 g/kg; sulfur, 2 g/kg; zinc, 520 mg/kg; copper, 180 mg/kg; manganese, 145 mg/kg; iodine, 10 mg/kg; selenium, 2.5 mg/kg; cobalt, 10 mg/kg; iron, 360 mg/kg; vitamin A, 30,000 U/kg; vitamin D₃, 1500 U/kg; vitamin E 500 U/kg.

Table 2. Total milk yield and 4% fat-corrected milk of cows receiving sodium selenite (inorganic selenium) and selenium yeast (organic selenium) during the 124 experimental days.

Variable	Treatment	N	Mean	Median	Standard deviation	Standard error	P
Total milk yield	Inorganic Se	9	2247.3	2147.8	295.4	98.4	0.95
	Organic Se	9	2251.9	2299.1	286.0	95.3
Milk corrected yield (4% fat)	Inorganic Se	9	2233.8	2134.9	293.6	97.8	0.39
	Organic Se	9	2302.6	2350.8	292.4	97.4

Se, selenium.

Table 3. Number of observations, mean, standard deviation, median, median difference and probability of the variables of milk quality of animals receiving sodium selenite (inorganic selenium) and selenium yeast (organic selenium).

	Treatment	N	Mean	Standard deviation	Median	Median difference	P
Fat, %	Inorganic Se	171	4.07	0.66	3.96	-0.19^°	0.01
	Organic Se	171	4.17	0.62	4.15
Protein, %	Inorganic Se	169	3.09	0.25	3.11	0.11	0.80
	Organic Se	169	3.09	0.35	3.00
Lactose, %	Inorganic Se	170	4.52	0.26	4.60	0.07	0.49
	Organic Se	170	4.51	0.19	4.53
Total solids, %	Inorganic Se	171	12.62	0.89	12.56	-0.25	0.16
	Organic Se	171	12.72	0.97	12.81
NDE, %	Inorganic Se	170	8.55	0.39	8.55	-0.05	0.74
	Organic Se	170	8.55	0.42	8.60
Somatic cells,	Inorganic Se	171	7.32	1.66	7.54	1.00^°	0.01
log2/mL	Organic Se	171	6.93	2.65	6.54

N, number of observations; Se, selenium; NDE, non-fat dry extract.

°Significance for difference of medians by Wilcoxon’s test at 5% probability.

Table 4. Number of observations, mean, standard deviation, median, median difference and probability of the respiratory frequency, rectal temperature and haircoat temperature of animals receiving sodium selenite (inorganic selenium) and selenium yeast (organic selenium).

	Treatment	N	Mean	Standard deviation	Median	Median difference	P
RF, breaths/min	Inorganic Se	153	58.04	17.26	57.00	-3.00^°	0.027
	Organic Se	153	59.90	14.77	60.00
RT, °C	Inorganic Se	153	38.98	0.59	39.00	-0.05	0.435
	Organic Se	152	39.08	0.55	39.05
HT, °C	Inorganic Se	153	35.88	1.33	36.22	0.14^°	0.007
	Organic Se	153	35.65	1.48	36.08

N, number of observations; RF, respiratory frequency; RT, rectal temperature; HT, haircoat temperature.

°Significance for difference of medians by Wilcoxon test at 5% probability.