Italian local goat breeds have better milk coagulation properties than cosmopolitan breed

Figures & data

Table 1. Hay and concentrate chemical composition and energy content fed to the goats during the trial.

Trait	Hay	Concentrate
DM, %	89.1	88.2
Crude protein, % of DM	15.1	21.7
Fat, % of DM	1.9	3.5
NSC, % of DM	20.7	42.7
Cellulose, % of DM	29.5	10.5
Ash, % of DM	9.5	9.1
NDF, % of DM	52.6	23.0
ADF, % of DM	36.6	9.0
ADL, % of DM	3.9	3.3
NEL, Mcal/kg DM	1.10	1.77

DM, dry matter; NSC, non-structural carbohydrates; NDF, neutral detergent fibre; ADF, acid detergent fibre; ADL, acid detergent lignin; NEL, net energy of lactation.

Table 2. Descriptive statistics of milk coagulation properties (MCP), composition traits, pH and SCS of goat milk.

	Before editing	After editing
Trait	Initial N	N	Mean	SD	CV, %	Minimum	Maximum
Milk coagulation properties
RCT, min	164	154	9.36	2.52	26.99	4.00	16.15
k20, min	150	144	3.68	1.89	51.42	1.30	10.30
a30, mm	164	160	25.56	9.67	37.84	6.00	46.00
Milk composition
Fat, %	164	159	3.60	0.77	21.37	1.91	5.38
Protein, %	164	161	3.42	0.39	11.33	2.48	4.39
Lactose, %	164	157	4.41	0.22	5.09	4.00	4.86
pH	164	160	6.56	0.11	1.70	6.31	6.80
SCS, units	145	135	5.72	1.72	30.13	0.75	9.99

Before editing refers to the n of samples with records on each parameter after removing five samples that did not present milk composition and seven samples that did not coagulate.

RCT, rennet coagulation time; k₂₀, curd-firming time; a₃₀, curd firmness 30 min after rennet addition to milk; SCS, somatic cell score; CV, coefficient of variation.

Table 3. Least squares means of milk coagulation properties (MCP), milk composition, pH and SCS for goat breeds.

	Breed
Trait	Garganica	Girgentana	Maltese	Med. Red	Saanen
Milk coagulation properties
RCT, min	9.16 ± 0.50^b	9.69 ± 0.50^b	9.12 ± 0.48^b	7.66 ± 0.55^b	12.05 ± 0.60^a
k20, min	3.31 ± 0.46^b	3.70 ± 0.48^b	3.62 ± 0.45^b	3.09 ± 0.52^b	6.00 ± 0.58^a
a30, mm	21.72 ± 1.54^b	31.44 ± 1.53^a	25.25 ± 1.49^ab	26.52 ± 1.68^ab	22.64 ± 1.66^b
Milk composition
Fat, %	3.82 ± 0.16	3.42 ± 0.16	3.68 ± 0.15	3.83 ± 0.17	3.17 ± 0.17
Protein, %	3.68 ± 0.09^a	3.48 ± 0.09^a	3.50 ± 0.08^a	3.30 ± 0.10^ab	3.05 ± 0.09^b
Lactose, %	4.47 ± 0.04^ab	4.42 ± 0.04^ab	4.35 ± 0.04^b	4.56 ± 0.05^a	4.31 ± 0.04^b
pH	6.51 ± 0.02^b	6.53 ± 0.02^b	6.57 ± 0.02^ab	6.53 ± 0.02^b	6.65 ± 0.02^a
SCS, units	5.84 ± 0.40	5.63 ± 0.35	4.85 ± 0.38	6.06 ± 0.39	5.98 ± 0.39

Least squares means with different superscript letters within a row are significantly different (p < .05).

RCT, rennet coagulation time; k₂₀, curd-firming time; a₃₀, curd firmness 30 min after rennet addition to milk; SCS, somatic cell score.

Figure 1. Least squares means (with standard errors) of rennet coagulation time (RCT, min; •), curd-firming time (k₂₀, min; ▵) and curd firmness 30 min after rennet addition to milk (a₃₀, mm; ▪) across month of lactation.

Figure 2. Least squares means (with standard errors) of fat percentage (○), protein percentage (▵), lactose percentage (□), pH (•) and SCS (▪) across month of lactation.

Table 4. Pearson’s correlation coefficients between residuals of milk composition, pH, SCS and milk coagulation properties (MCP).

	Fat	Lactose	pH	SCS	RCT	k20	a30
Protein	0.26***	0.19*	0.04	0.11	−0.12	−0.46***	0.29***
Fat		0.20*	0.04	0.05	−0.12	−0.06	0.02
Lactose			0.16*	−0.37***	−0.10	−0.09	0.26***
pH				−0.12	0.42***	0.29***	−0.18**
SCS					−0.03	−0.14	−0.15
RCT						0.62***	−0.32***
k20							−0.41***

RCT, rennet coagulation time; k₂₀, curd-firming time; a₃₀, curd firmness 30 min after rennet addition to milk; SCS, somatic cell score.

***p < .001.

**p < .01.

*p < .05