1. CHARACTERIZATION OF MILK COAGULATION ABILITY IN BULK MILK SAMPLES
Valentina Toffanin, Massimo De Marchi, Mauro Penasa,
Denis Pretto, Martino Cassandro
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

2. Introduction
At the global level there is a growth in production and consumption of cheese
At present, 70% of the available milk in Italy is used for cheese production and about 35% is transformed into PDO products (Pieri, 2011).
As reported by Pretto et al. (2012), Cassandro et al. (2008) and Summer et al. (2002), basic requirements for cheese-making are milk coagulation properties (MCP)
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

3. RCT k20 a30 What is MCP ? milk + rennet minutes 30
minutes
RCT
Rennet Clotting Time (min)
k20
Curd Firming Time (min)
20mm
a30
Curd Firmness (mm)
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

4. Sources of variation for MCP
Herd & breed [De Marchi et al. (2007), Tyrisevä et al. (2002) and Mariani et al. (2002, 1997)]
Season [Barlowska et al. (2012), Chládek et al. (2011), Jõudu et al. (2008) and De Marchi et al. (2007)]
Chemical composition [Protein & Casein: Jõudu et al. (2008). Somatic Cell Count: Politis and Ng-Kwai-Hang (1988) and Okigbo et al. (1985b). Titratable acidity & pH: Formaggioni et al. (2001) and Okigbo et al. (1985a)]
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

5. Aim
To investigate dairy cooperative, herd, season and milk quality and acidity traits on MCP (RCT, k20, a30) in bulk samples
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

6. Material
&
Methods
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

7. Material and methods / milk analyses
1,570 bulk milk samples, June ‘08 – November ‘09, 436 dairy herds, 4 dairy cooperatives
MilkoScan 6000 for fat, protein, casein contents
Cell Fossomatic for Somatic cell content (SCC)
Crison Compact D for pH, titratable acidity (TA)
Computerized renneting meter for RCT, k20, a30 (according to the methodology of Cassandro et al., 2008)
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

8. Material and methods / statistical analyses
GLM procedure of SAS: ANOVA on MCP
Linear model:
Y : RCT, k20, a30
X : dairy cooperative, herd (dairy cooperative), year of sampling, season of sampling, classes of casein, fat, titratable acidity, somatic cell count, bacterial count
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

9. Results and discussion
k20, min
RCT, min N
Mean
S.D.
Skewness
Curtosi
RCT
1508
18.83
3.68
0.08
0.33
k20
1193
6.85
1.92
0.35
0.25
a30
26.97
8.12
-0.18
0.15
a30, mm
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

10. Results and discussion
Results from ANOVA for milk coagulation properties of bulk milk samples.
RCT1, min
k202, min
a303, mm
Effect F
P-value
Dairy cooperative4
25.03
<0.001
9.36
25.57
Herd (within dairy cooperative)
1.86
1.57
1.83
Year of sampling
19.08
1.12
0.290
0.07
0.797
Season of sampling
13.75
2.66
0.047
1.51
0.211
Casein, %
0.71
0.585
4.84
0.001
5.88
Fat, %
0.58
0.676
1.06
0.376
1.47
0.209
Titratable acidity, °SH/50mL
14.31
4.78
13.63
Somatic cell count, cells/mL
2.31
0.056
1.13
0.339
0.97
0.422
Bacterial count, cells/mL
2.48
0.042
1.70
0.148
1.56
0.183 R2
0.52
RMSE5
3.03
1.65
6.72
1RCT = rennet coagulation time; 2k20 = curd-firming time; 3a30 = curd firmness. 4Tested on herd within dairy cooperative variance. 5RMSE = root mean square error.
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

11. Results and discussion
Least square means of dairy effect on milk coagulation traits. RCT = rennet coagulation time (min); k20 = curd-firming time (min); a30 = curd firmness 30 minutes after rennet addition (mm). a b b ab b b
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

12. Results and discussion
Effect of season of sampling on RCT and k20. RCT = rennet coagulation time (min); k20 = curd-firming time (min); a30 = curd firmness 30 minutes after rennet addition (mm).
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

13. Results and discussion
Least squares means of rennet coagulation time (RCT, min) across classes of (a) titratable acidity and (b) somatic cell count.
Titratable acidity (°SH/50mL): C1 < 3.00; C to 3.20; C to 3.40; C to 3.60; C5 > 3.60.
Somatic cell count: C1 < 100,000; C2 100,000 to 200,000; C3 200,000 to 300,000; C4 300,000 to 400,000; C5 > 400,000.
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

14. Results and discussion
Least squares means of curd-firming time (k20, min) across classes of (a) casein content and (b) titratable acidity.
Casein content: C1 < 2.37; C to 2.52; C to 2.67; C to 2.82; C5 > 2.82.
Titratable acidity (°SH/50mL): C1 < 3.00; C to 3.20; C to 3.40; C to 3.60; C5 > 3.60.
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

15. Results and discussion
Least squares means of curd firmness (a30, mm) across classes of (a) casein content and (b) titratable acidity.
Casein content: C1 < 2.37; C to 2.52; C to 2.67; C to 2.82; C5 > 2.82.
Titratable acidity (°SH/50mL): C1 < 3.00; C to 3.20; C to 3.40; C to 3.60; C5 > 3.60.
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

16. Conclusions
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

17. Summarizing Favorable MCP Effect summer n. s. + - Perspectives:
<RCT
<k20
>a30
Season
summer
n. s.
Casein + TA
SCC -
Perspectives:
Studying the effect of farm characteristics on MCP (e.g. herd structures, management and feeding strategies, breed composition of dairy)
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012

18. Thanks to
Lattebusche (Busche, Italy) Latteria di Soligo (Soligo, Italy) Latterie Trevigiane (Vedelago, Italy) Latterie Vicentine (Bressanvido, Italy) Breeders Association of Veneto region (ARAV, Padova, Italy) Veneto Agricoltura (Thiene, Italy)
And… YOU!
20th International Symposium Animal Science Days - Kranjska gora, Sept. 19th-21th, 2012