Evaluation of fully oxidised β-carotene as a feed ingredient to reduce bacterial infection and somatic cell counts in pasture-fed cows with subclinical mastitis

Figures & data

Table 1. Number of lactating cows in herds included in a study of the effect of feeding oxidised β-carotene (OxBC) on clinical and subclinical mastitis, and their estimated dry matter (DM) intake of pasture, supplementary feeds, Mg, Ca, and pelleted feed, that did (Treatment) or did not (Control) contain oxidised β-carotene.

	Farm B	Farm S	Farm T	Farm W
No. lactating cows	424	777	799	632
Approximate intake (kg DM/cow/day)
Pasture	15	14	14	15.5
Palm kernel expeller	4	NF	NF	NF
Maize silage	1	NF	2	NF
Dried distillers’ grain	0.6	NF	NF	NF
Corn gluten	0.6	NF	NF	NF
Dairy meal	NF	2	NF	2
Tapioca	NF	NF	1	NF
Total	21.2	16	17	17.5
Intake (g/cow/day)
Mg (as MgO)	57	23	29	15
Ca (as CaCO3)	40	40	29	60
Mean (±SD) estimated intake of pellet (kg/cow/day)^a
Control cows	0.53 ± 0.04	0.52 ± 0.01	0.54 ± 0.01	0.52 ± 0.02
Treatment cows	0.52 ± 0.04	0.53 ± 0.01	0.54 ± 0.01	0.51 ± 0.02

^a Cereal-based dairy pellet that did (Treatment) or did not (Control) contain 300 mg of fully oxidised β-carotene.

NF = Not fed.

Figure 1. CONSORT diagram showing the numbers of dairy cows assessed, excluded and enrolled in a study to determine the effect of feeding oxidised β-carotene (OxBC) on clinical and subclinical mastitis.

Table 2. Distribution of numbers of cows assigned to be fed a cereal-based dairy pellet that did (Treatment) or did not (Control) contain 300 mg of oxidised β-carotene (OxBC), by herd, breed, age, and days in milk at commencement of feeding.

Variable	Control	Treatment
Farm
B	7	7
W	13	15
T	34	34
S	22	21
Breed^a
Friesian	29	29
Other	47	48
Age
Primiparous	7	7
Multiparous	69	70
Days in milk
15–60	20	24
61–75	18	19
76–90	26	21
>90	12	13

^a Friesian is ≥12/16 Friesian.

Table 3. Numbers of milk samples collected from quarters of cows 0, 21 and 42 days after the commencement of feeding a cereal-based pellet that did (Treatment) or did not (Control) contain oxidised β-carotene, categorised by culture result.

	Control			Treatment
Culture result	Day 0	Day 21	Day 42	Day 0	Day 21	Day 42
No growth	0	21	15	0	19	24
Staphylococcus aureus	11	9	11	10	8	11
Streptococcus dysgalactiae	1	4	3	1	1	2
Strep. uberis	14	8	11	20	17	15
Mixed major^a	3	1	3	2	1	4
CNS	34	25	26	30	25	20
Corynebacterium spp.	66	59	53	52	43	45
Mixed minor^b	1	3	8	2	9	2
Serratia spp.	0	0	0	1	0	0
Yeasts	5	4	4	11	4	5
Total	135	135	135	129	129	128

^a A major pathogen (i.e. Staph aureus, Strep. dysgalactiae or Strep. uberis) and a minor pathogen (i.e. CNS or Corynebacterium spp.) were isolated.

^b Two minor pathogens (i.e. CNS or Corynebacterium spp.) were isolated.

CNS = Coagulase-negative staphylococci.

Figure 2. Estimated marginal mean (95% CI) ln quarter-level somatic cell counts (SCC) measured in milk samples collected from cows 0, 21 and 42 days after the commencement of feeding a cereal-based pellet that did (●) or did not (△) contain oxidised β-carotene.

Figure 3. Estimated mean (95% CI) proportion of quarters with somatic cell counts (SCC) <200,000 cells/mL measured in milk samples collected from cows 21 and 42 days after the commencement of feeding a cereal-based pellet that did (●) or did not (△) contain oxidised β-carotene.