Effects of breed and milking frequency on udder histological structures in dairy goats

Figures & data

Table 1. Effect of breed and milking frequency on tissue parameters and milk volume in udders of dairy goats.¹

				Milking frequency^2
	Majorera	Tinerfeña	Palmera	×1	×2
Tissue parameters	(n=34)	(n=35)	(n=35)	(n=53)	(n=54)
Secretory tissue (%)	47.63^a±5.86	43.94^b±6.69	45.40^ab±6.15	46.56±7.15	45.15±5.49
Connective tissue (%)	49.95^a±5.80	54.23^b±6.02	51.48^ab±5.82	51.33±6.58	52.31±5.59
Excretory tissue (%)	1.75±2.84	1.21±1.54	1.89±2.06	1.56±2.60	1.68±1.79
Vascular tissue (%)	0.67±0.56	0.62±0.53	1.23±1.65	0.87±1.41	0.82±0.57
Alveoli number	264.50^a±55	211.70^b±39.36	278.13^a±55.16	246.57±58.08	258.35±53.36
Alveoli area (µm^2)	17.13^ab±4.73	19.81^a±6.39	15.11^b±3.58	18.21±5.91	16.62±4.28
Note: Means with different superscript letters are statistically different (P < 0.05).
^1Data are the means±SD of all the samples for each breed and milking frequency.
^2Once (×1) or twice (×2) daily milking.

Table 2. Correlations between morphological and histological measures of the udder in dairy goats.

	DT	UD	CF	TF
UD	0.46
CF	0.13	−0.23
TF	0.31	−0.17	0.72**
CMY	0.53*	0.52*	−0.31	−0.26
CMP	−0.06	−0.32	−0.36	0.04
AMY	0.46	0.68**	−0.05	−0.23
AMP	0.06	0.32	0.36	−0.04
TM	0.53*	0.58*	−0.26	−0.26
HP	0.64**	0.68**	−0.15	0.16
Fat	0.13	−0.19	0.39	0.11
Protein	0.05	−0.15	0.35	0.18
Lactose	0.44	0.45	0.46	0.37
Weight	0.35	0.54*	−0.56*	−0.35
Secretory tissue	−0.18	0.41	0.22	−0.20
Connective tissue	0.17	−0.38	−0.32	0.15
Excretory tissue	0.11	−0.30	0.48*	0.30
Alveoli area	−0.33	−0.10	−0.50*	−0.62**
Alveoli number	0.35	0.32	0.67**	0.53*
DT, distance between teats; UD, udder depth; CF, cistern–floor distance; CMY, cisternal milk yield; CMP, cisternal milk percentage; AMY, alveolar milk yield; AMP, alveolar milk percentage; TM, total milk; HP, milk production per hour.
*P < 0.05; **P < 0.01.

Table 3. Correlations between milk yielding and fractioning and histological measures in dairy goats.

	CMY	CMP	AMY	AMP	TM	HP
CMP	0.05
AMY	0.77**	−0.57*
AMP	−0.05	−1.00**	0.57*
TM	0.99**	−0.10	0.86**	0.10
HP	0.53*	−0.09	0.50*	0.09	0.54*
Fat	−0.04	−0.47*	0.22	0.47*	0.02	−0.16
Protein	−0.24	−0.28	−0.03	0.28	−0.20	−0.42
Lactose	0.25	−0.23	0.38	0.23	0.29	0.20
Weight	0.43	0.30	0.22	−0.30	0.40	0.46
Secretory tissue	−0.12	−0.48*	0.25	0.48*	−0.04	−0.15
Connective tissue	0.16	0.54*	−0.24	−0.54*	0.07	0.18
Excretory tissue	−0.15	−0.04	−0.18	0.04	−0.16	−0.14
Alveoli area	−0.06	0.34	−0.25	−0.34	−0.11	−0.30
Alveoli number	0.09	−0.62**	0.45	0.62**	0.18	0.38
CMY, cisternal milk quantity; CMP, cisternal milk; AMY, alveolar milk quantity; AMP, alveolar milk; TM, total milk; HP, milk production per hour.
*P < 0.05 **P < 0.01.

Table 4. Correlations between milk quality and histological measures in dairy goats.

	Fat	Protein	Lactose
Protein	0.14
Lactose	0.18	0.35
Weight	−0.66**	−0.02	0.01
Secretory tissue	−0.20	0.26	0.28
Connective tissue	0.06	−0.28	−0.30
Excretory tissue	0.70**	0.04	0.13
Alveoli area	−0.55*	0.12	−0.32
Alveoli number	0.47*	−0.09	0.48*
*P < 0.05; **P < 0.01.