Non-parametric analysis of the effects of nongenetic factors on milk yield, fat, protein, lactose, dry matter content and somatic cell count in Murciano-Granadina goats

Figures & data

Table 1. Category description for non-genetic environmental factors considered in Murciano-Granadina goats.

Factor	Type	Levels
Farm	Nominal	25 farms
Parturition month	Ordinal	January, February, March, April, May, June, July, August, September, October, November, and December
Parturition season	Ordinal	Spring, Summer, Autumn and Winter
Parturition year	Ordinal	2006–2018
Birth type	Nominal	Abortion in lactation, Simple, Double, Triple, Quadruple
Parity order	Numeric	1–9 births
Alive kid number	Numeric	0–4 kids
Stillborn/Dead kid number	Numeric	0–2 kids (whichever the cause of their death is)
Number of control	Numeric	1–33 controls
OMET (Type of control)	Nominal	A4 (milking happens each 4 weeks), AT4M (milking happens each 4 weeks always in the morning), AT4T (milking happens each 4 weeks always in the afternoon), A6 (milking happens each 6 weeks), AT6M (milking happens each 6 weeks always in the morning) and AT6T (milking happens each 6 weeks always in the afternoon)
Days in milk	Numeric	0–182 Days
Days to first control	Numeric	0–225 Days
Days from last control to drying	Numeric	0–60 Days
Control month	Ordinal	January, February, March, April, May, June, July, August, September, October, November, and December
Control season	Ordinal	Spring, Summer, Autumn and Winter
Control year	Ordinal	2006–2018
Drying month	Ordinal	January, February, March, April, May, June, July, August, September, October, November, and December
Drying season	Ordinal	Spring, Summer, Autumn and Winter
Drying year	Ordinal	2007–2018

Table 2. Summary of the results for Kruskal Wallis H Ranks test, partial eta squared and Cohen’s f for the levels of the factors of farm, parity order, birth number, number of alive and dead kids, month, season and year of birth affecting milk yield (g), fat (%), protein (%), dry matter (%), lactose (%) and somatic cell count (SCC × 10³ sc/mL) and their biological translation.

Variables Factors	Milk yield	Protein	Fat	Dry matter	Lactose	Somatic cells count
Farm	Significant differences across the 28 farms (600–5,347 g for milk yield, 3.005–4.660 % for protein, 4.290–7.210 % for fat, 12.530–17.740 % for dry matter, 3.790–4.980 % for lactose and 112.000–1970.000 sc/mL for somatic cells
Parity order	First parturition goats produced the lowest amount (1,832 g). Production then increased from the second birth to the fourth (2,696 g), to fall beyond this point (up to 1,400 g, ninth lactation)	Small increase as parity order increased (SD 0.092%)	Increased beyond fourth parturition (5.500 %)	No significant differences	Primipara goats produced the highest content (4.810%), followed by 2nd parturition does (4.780%). From 5th parturition on, lactose declined (until 4.590%)	Closely linked. Increases with parity order (from 378.000 to 1969.000 sc/mL from 1st to 9th parturition)
Birth number and number of alive kids	Higher as litter size (more than two alive kids) increased (from 2,052 to 3,240 g). In goats that aborted, but begin lactation, production was significantly higher (2,418 g) than in single-birth goats (2,052 g) and similar to double-birth goats (2,434 g)	Goats that aborted and continued in lactation, produced slightly higher percentage of protein (3.670%). No difference for goats giving birth to 1– 3 alive kids (SD 0.066 %)	Decreased linearly as the litter size increased (more than one alive kid) from 5.440 to 4.880 % for fat, from 14.600 to 13.750 for dry matter and from 4.760 to 4.610 % for lactose			Lower somatic cells counts were present in simple birth goats (452.500 sc/ml) increasing with alive kid number up to 1012.000 sc/mL (4 alive kids). Goats that aborted but lactated, somatic cells increased compared to single births (782.000 sc/mL)
Born dead kids	When some of the kids were born dead, milk production increased (2,490 g). However, production decreased significantly in births where both twins were born dead (900 g)	No effect was found				The birth of one dead kid implied an increase (1285.000 sc/mL), unlike what happened when two kids were born dead (384.000 sc/mL)
Month of birth	Goats kidding in January and March produced more milk (2,815–2,820 g). However, yield decreased in goats born during June to October (from 2.717 to 1,699 g)	The opposite trends described for milk yield			Goats kidding in the month of October and November produced more lactose (4.840–4.870 %)	Births in February related to lower somatic cells counts (295.000 sc/ml), with a tendency to rise from March, with a peak in July (1053 sc/mL), which decreased towards December up to 493.000 sc/ml
Season of birth	Goats kidding in autumn and winter reported the highest milk yields (2,575–2,686 g), decreasing during spring and summer (1,960 to 2,226 g)	Decreased from spring-summer to autumn-winter from 3.450 to 3.620 % for protein, from 5.530 to 5.000 % for fat, from 13.925 to 14.790 % for dry matter and from 4.670 to 4.810 % for lactose				Lowest somatic cells counts recorded in winter (444.000 sc/mL), increasing towards spring (747.500 sc/mL) to decrease in summer (595.000 sc/mL)
Year of birth	An increase was observed over the years up to reach 2,981 g, decreasing progressively towards 2018 (1,344 g)	Constant over the years with a peak in 2018 of 5.450 % in protein, 8.140 % in fat and 5.450 % in 18.920% in dry matter			Progressively decreased until 2018 (from 4.870 % in 2009 to 4.410 % in 2018)	Fluctuated over the years (from 305.000 to 4632.000 sc/mL), significantly increasing from 2017 on

The results presented are significant at p < .05 at minimum [for specific statistical information see Supplementary Tables S2, S3 and S4.]

Table 3. Summary of the results for Kruskal Wallis H Ranks test, partial eta squared and Cohen’s f for the effects of all the levels of the factors of control number, type of control, month, season and year of control, days in milk, days from last control to drying, days to first control, month, season and year of drying affecting milk yield (g), fat (%), protein (%), dry matter (%), lactose (%) and somatic cell count (SCC × 10³ sc/mL) and their biological translation.

Variables Factors	Milk yield	Protein	Fat	Dry matter	Lactose	Somatic cells count
Number of Control	Relatively constants (Variation coefficient of 34.552 % for milk yield, 10.597 %, for protein 7.206 % for fat, 5.408 % for dry matter and 2.417 % for lactose. Milk yield and lactose described the opposite trend to protein, dry matter and fat with median g and percentual contents progressively and slightly decreasing from first to last control					Progressively increased from third control on (from 377.500 sc/mL to 2.868 sc/mL)
Type of Milk Control	A4, AT4T and AT4M controls collected a higher amount of milk (μ: 2,346 g) compared to A6, AT6M and AT6T controls (μ: 1,440 g)	Highest quantities recorded for A6 control (3.950 %)	The highest fat (μ: 5.998 %) and dry matter (μ: 15.040 %) contents collected in AT4T, A6 and AT6T controls		A6 control reported the lowest contents (4.255 %), while AT4M and AT6M controls reported the highest values (μ: 4.820 %)	The AT4M control reported the lowest values (508.000 sc/mL). No differences reported for the rest of control types except for AT6T (1021.000 sc/mL)
Control month and season	Remained stable throughout the year (Variation coefficient of 7.455%), with the exception of November to January, when it slightly decreased (from 2,700 to 2,112 g). Higher milk yields collected from Spring controls (2,500 g). No differences between autumn and summer. Decreased in winter up to 2,200 g	Decreased during the months from April to September, with July and August being the months with the lowest contents (3.220 % for protein, 4.475 % for fat, 13.230 % for dry matter and 4.600 % for dry matter). Highest values for these variables were reached during winter months (3.700 % for protein, 5.760 % for fat, 15.100 % for dry matter and 4.840 % for lactose while the lowest ones were reported during spring (3.330 % for protein, 4.620 % for fat, 13.430 % for dry matter and 4.610 % for lactose)				Remained stable from January to May (Variation Coefficient of 4.686%), slightly increasing from June-December (Variation coefficient of 13.511%), except for August (509.500 sc/mL). Overall, slightly higher in spring-summer (μ: 685.500 sc/mL) than in autumn-winter (μ: 541.000 sc/mL)
Control year	Lower amounts were reported prior to 2013 (μ: 2,038 g). Peak reached in 2014 (3,020 g), then levels decreased in 2017 (1,888 g) slightly recovering in 2018 (2,352 g)	Relatively stable over the years (SD 0.147 %), increasing from 3.440 % in 2008 to 3.760 % in 2018	Remained stable over the years (Variation coefficient of 5.064% for fat and 1.541 % for dry matter)		Decreased over the years from 4.855% in 2006 to 4.535 % in 2018	Increased over the years from 317.000 sc/mL in 2008 to 1480.000 sc/mL in 2018
Days in Milk (DIM)	Slight decrease in production from day 30 (before 30 DIM, μ: 2,380 g, after 30 DIM, μ: 2,049 g)	Maintains stable values throughout lactation (Variation coefficient 7.841%)	Significantly increased (before 30 DIM, μ: 5.164 and 14.282 %, after 30 DIM, μ: 5.465 and 14.676 % for fat and dry matter, respectively)		Maintains stable values throughout lactation (Variation coefficient 3.376 %)	Describes oscillating values throughout the lactation period (Coefficient of variation of 79.658 %)
Days from last control to drying	Remained relatively stable with slight significant increases as days from last control progress to drying (Coefficient of variation of 27.022% for milk yield, 7.856 % for protein, 12.645% for fat, 5.857 % for dry matter and 3.407 % for lactose contents. Lactose content decreases as period between last control to drying shortens from 4.965 % (2 months prior to drying) to 4.330 % (3 days prior to drying)					Decreased as number of days from last control to drying reduce from 112.500 sc/mL (55 days prior to drying) and 2579.000 sc/mL (7 days prior to drying)
Days to First Control	Levels become irregular when there is a month or more to first control (Variation coefficient: 30.709%)	Stable levels with slight increases as days to first control increase with variation coefficients of 7.637 % for protein, 11.069% for fat, 5.711 % for dry matter and 3.722 % for lactose				Highest counts (2320.000 sc/mL) when it took over two months to first control
Month and season of drying	Goats drying in October produced the highest yields (2,989 g), followed by goats drying in February, March, and September to December (μ: 2,723 g). Goats drying in April produced the lowest milk yield (1,287 g). Goats drying in autumn produced the highest milk yields (2,870 g)	April (spring) was the month reporting the highest contents (3.845 % for protein, 5.930 % for fat and 15.260 % for dry matter). Contents slightly decreased from September to December (autumn to winter) around 0.150 %			Stable levels across months, only slightly decreasing from August to November, to slightly increase again until July-August after which the same cycle repeats (SD 0.059 %)	Increased from January to April (with a peak in spring of 1182.000 sc/mL), decreasing afterwards in autumn, when the lowest values are reached (488.000 sc/mL)
Drying year	Progressive increase until 2014 (3,100 g), when levels decreased until 2,055 g in 2017	Progressive increase over the years from 3.150 to 3.860 %	No significant effect (p > .05)		Decreased over the years from 5.060 to 4.545 %	Progressive increase over the years from 299.000 sc/mL to 1221.000 sc/mL

The results presented are significant at p < .05 at minimum [for specific statistical information see Supplementary Tables S2, S3 and S4.]