Biochemical profile and milk fat/protein in Saanen and Nubian goats

[Perfil bioquímico e gordura/proteína do leite em cabras Saanen e Nubian]

ABSTRACT

The biochemical profile and milk fats/proteins in Saanen and Nubian goats from Los Asmoles, Colima was carried out. Milk fat, milk protein, fat/protein ratio, glucose (GLU), cholesterol (COL), non-esterified fatty acids (NEFA), triacylglycerol (TAG), β-hydroxybutyrate (β-HBA), blood urea nitrogen (BUN), albumin (ALB), globulin (GLOB), total protein (PROT-T), calcium ion (Ca²⁺), inorganic phosphate (Pi), sodium ion (Na⁺), potassium ion (K⁺), magnesium ion (Mg²⁺), and chloride ion (Cl^-) was calculated. The biochemical profile results were consistent with the international literature for goats. All analytes except ALB and β-HBA showed racial differences. The three milk variables registered a higher concentration in Nubian. The comparison between groups (high-yield vs. low-yield vs. dry period) showed differences in COL and β-HBA in both breeds. A negative correlation between GLU and NEFA was quantified. Positive correlations between NEFA with COL, TAG and β-HBA, between Ca²⁺ with Na⁺ and between K⁺ with Na⁺ and Mg²⁺ were quantified. Milk fat was correlated with COL, NEFA and β-HBA. Milk protein was correlated with BUN. The fat/protein ratio was correlated with COL and β-HBA. Results provide insight into metabolic adaptations in lactation and identify links between key analytes and milk fat/protein in goats.

Keywords:
blood chemistry; metabolic profile; milk fat/protein; goat milk

RESUMO

Foi realizado o do perfil bioquímico e das gorduras/proteínas do leite em cabras Saanen e Nubian de Los Asmoles, Colima. Gordura do leite, proteína do leite, relação gordura/proteína, glicose (GLU), colesterol (COL), ácidos graxos não esterificados (NEFA), triacilglicerol (TAG), β-hidroxibutirato (β-HBA), nitrogênio ureico no sangue (BUN), albumina (ALB), globulina (GLOB), proteína total (PROT-T), íon cálcio (Ca²⁺), fosfato inorgânico (Pi), íon sódio (Na⁺), íon potássio (K⁺), íon magnésio (Mg²⁺) e íon cloreto (Cl^-) foram calculados. Os resultados do perfil bioquímico foram consistentes com a literatura internacional para caprinos. Todas as análises, exceto ALB e β-HBA, mostraram diferenças raciais. As três variáveis ​​lácteas registraram maior concentração no Nubian. A comparação entre os grupos (alto rendimento vs. baixo rendimento vs. período seco) mostrou diferenças em COL e β-HBA em ambas as raças. Uma correlação negativa entre GLU e NEFA foi quantificada. Foram quantificadas correlações positivas entre NEFA com COL, TAG e β-HBA, entre Ca²⁺ com Na⁺ e entre K⁺ com Na⁺ e Mg²⁺. A gordura do leite foi correlacionada com COL, NEFA e β-HBA. A proteína do leite foi correlacionada com a BUN. A relação gordura/proteína foi correlacionada com COL e β-HBA. Os resultados fornecem informações sobre as adaptações metabólicas na lactação e identificam ligações entre as principais análises e gordura/proteína do leite em cabras.

Palavras-chave:
química do sangue; perfil metabólico; gordura/proteína do leite; leite de cabra

INTRODUCTION

Goat milk has become an important element of human nutrition (Bauman et al., 2006). The companies that collect goat milk use this product mainly for the production of cheeses (Markets…, 2023). For this reason, it is necessary to increase our understanding of energy, lipid, protein, and mineral metabolism (Nayik et al., 2021; Fraser et al., 2022; Lima et al., 2022), from metabolic profile that allow us to understand the biochemical correlations involved in fat esterification and protein translation of goat milk. Metabolites are the end products of complex interactions that occur within the cell and events that occur outside the cell or organism (Benedet et al., 2019). The metabolic profile test was invented in the late 1960s as a means of diagnosing various forms of production diseases in dairy cows (Payne, 1972), but it was quickly extended to all production animals. The metabolic profiles represent the way to know all factors that could have an influence in the metabolic status of animal tissues, to assess disorders of organ function, adaptation of the animal to nutritional and physiological challenges, and specific nutritional imbalances (Henna et al., 2021). This information can be accessed by measuring and interpreting some blood parameters in a clinical context, even before the productivity of the herd is affected. Consequently, this research seeks to establish reference values for different biochemical analytes, in Saanen and Nubian goats from Los Asmoles, Colima that consider: i) Energy-lipid profile: glucose (GLU), cholesterol (COL), non-esterified fatty acids (NEFA), triacylglycerol (TAG), β-hydroxybutyrate (β-HBA), ii) Protein profile: blood urea nitrogen (BUN), albumin (ALB), globulin (GLOB), total protein (PROT-T), and Mineral-electrolyte profile: calcium ion (Ca²⁺), inorganic phosphate (Pi), sodium ion (Na⁺), potassium ion (K⁺), magnesium ion (Mg²⁺), and chloride ion (Cl^-). Subsequent, adjustments in the concentration of different biochemical analytes in response to fat/protein milk in goats were identified.

MATERIALS AND METHODS

This work was conducted as part of a population health assessment approved and supported by the Network Advances in Agricultural Research in Mexico. All the handing and sampling were performed in compliance with standard vertebrate protocols and veterinary practices, and in accordance with Bioethics and Animal Welfare Commission of the Faculty of Veterinary Medicine and Animal Husbandry - University of Colima. Evaluation act: No. 2/2021.

Data from 66 goats (33 Saanen and 33 Nubian) located in Association of Goat Farmers of the State of Colima, were used in this cross-sectional study. All farms were located in Los Asmoles, Colima, at the geographical coordinates 19° 01′ 32.48″ N and 103° 47′ 37.82″ W (Figure 1), altitude of 350 m s. n. m., average temperature of 25.6 °C, average precipitation of 962.3 mm (Statistical…, 2023), and warm sub-humid climate (Peel et al., 2007).

The sample size was determined by:

$n=\frac{Z^2\begin{array}{cc}pq& N\end{array}}{N{E}^2+Z^{2}pq}$

Where:

n = sample size

E = standard error (0.08)

Z = confidence level of 90% (1.645)

p = positive variability (0.5)

q = negative variability (0.5)

N = population size = 176 goats (88 Saanen and 88 Nubian)

$n=\frac{({1.645}^2)\begin{array}{cc}\left(0.5\right)\left(0.5\right)& \left(176\right)\end{array}}{\left(176\right)({0.08}^2)+({1.645}^2)\left(0.5\right)\left(0.5\right)}=\frac{119}{1.80}=66goats(33Saanenand33Nubian)$

Figure 1
Location of Los Asmoles, Colima

Goats were selected considering that the period of peak milk production is usually between 8 y 12wk. after calving; and the peak milk production generally begins to descend until 21wk. postpartum. Therefore, 66 goats (33 Saanen and 33 Nubian), were sampled in three groups: i) 22 high-yield goats [Days in milk (DIM): 90±15 d postpartum; Milk production (Mean±SD): 3.0±1.0L/d], ii) 22 low-yield goats [DIM: 240±15 d postpartum; Milk production (Mean ± SD): 1.0±0.4 L/d], and iii) 22 dry period goats (21±3 d prepartum). All animals were 2^nd calving healthy goats (confirmed by blood biometry). No external lesions and no ectoparasites, gastrointestinal nematode eggs were observed in the feces nor hemoparasites in blood smears.

The feeding of the high-yield goats diet included: dry-rolled sorghum, dry-rolled corn, oilseed paste, coconut paste, rice polishing, bypass fat, cane molasses, yeast inoculum, digestive enzymes, mycotoxin sequestrant, and vitamin premix. With 24.5% Crude Protein (CP), 4.8% Fat, 11.5% Moisture, and 45.2% Nitrogen Free Extract (NFE). The feeding of the dry period goats diet included: mixed cereals (sorghum, corn and/or wheat), oilseed paste, agro-industrial byproducts, vegetable oil, coccidiostats, and vitamin premix. With 20% CP, 2.4% Fat, 11.5% Moisture, and 52.8% NFE. The feeding of the low-yield goats diet included: mixture of 70% high-yield feed, and 30% dry period feed.

The three groups received mineral supplement with calcium carbonate (CaCO₃), tricalcium phosphate [Ca₃(PO₄)₂], sodium chloride (NaCl), magnesium oxide (MgO), manganese oxide (MnO₂), ferrous sulfate (FeSO₄), copper sulfate (CuSO₄), zinc oxide (ZnO), potassium iodide (KI), cobalt chloride (CoCl₂), sodium selenite (Na₂SeO₃), molasse, and fresh water. Additionally, they graze in rangelands with mixed species of: Tanzania guinea grass (Panicum maximum), Insurgent grass (Brachiaria brizantha), Signal grass (Brachiaria decumbens), African star grass (Cynodon nlemfuensis), and legumes: Guaje (Leucaena leucocephala), Huizache (Vachellia farnesiana), Cascalote (Caesalpinia coriaria), and Guácima (Guazúma ulmifolia) for periods of 4 to 8 h.

Blood samples were collected, after the first morning milking and before feeding, by puncture of the jugular vein using 8.5 mL vacuum tubes with clot activator and serum separator gel (BD Vacutainer 367988; Becton-Dickinson Co., Franklin Lakes, United States). The serum was separated by centrifuging directly at the farms at 1,500 x g for 10 min using a portable centrifuge (Porta-Spin C828; UNICO., Dayton, United States). Subsequently, the serum samples were separated using 1.5 mL tubes with lid (Tubes Safe-Lock 3810X; Eppendorf, Madrid, Spain) and transported at 4 °C in a portable cooler (Thermoelectric Cooler Car/Home M5644-710; Coleman Company, Kansas, United States) to the Clinical Laboratory of the University of Colima, where they were frozen at -20 °C until analysis. The concentration of each analyte was determined with an UV-Vis double beam spectrophotometer (Biochemistry Analyzer ES-218; KONTROLab., Guidonia, Italy). The biochemical analytes, the analytical method for each parameter, the units in which the results were expressed, and the corresponding commercial reagents, are described in Table 1.

Table 1
Biochemical analytes, units, analytical methods, and corresponding commercial reagents

Analyte*	Unit	Method	Reagent
Energy-lipid profile
Glucose (GLU)	mM	Trinder. GOD-POD1	1001190a
Cholesterol (COL)	mM	CHOD-POD. Liquid2	41020a
Non-esterified fatty acids (NEFA)	mM	Enzymatic3	FA 115b
Triacylglycerol (TAG)	mM	GPO-POD. Liquid4	41032a
β-hydroxybutyrate (β-HBA)	mM	Enzymatic. Ranbut5	RB1007b
Protein profile
Blood urea nitrogen (BUN)	mM	Urease-GLDH. Kinetic UV6	1001333a
Albumin (ALB)	g/L	Bromcresol green. Colorimetric	1001020a
Globulin (GLOB)	g/L	(PROT-T) - (ALB)	Difference
Total protein (PROT-T)	g/L	Biuret. Colorimetric7	1001291a
Mineral-electrolyte profile
Calcium ion (Ca2+)	mM	Arsenazo III. Colorimetric	CA2391b
Inorganic phosphate (Pi )	mM	Phosphomolybdate. UV8	1001155a
Sodium ion (Na+)	mM	O-Nitrophenyl-β-D-Glucoside9	1001385a
Potassium ion (K+)	mM	UV Test10	1001395a
Magnesium ion (Mg2+)	mM	Xylidyl Blue. Colorimetric11	1001286a
Chloride ion (Cl-)	mM	Thiocyanate-Hg. Colorimetric12	1001360a

• *Official abbreviation of the International Union of Pure and Applied Chemistry; ¹Glucose oxidase-peroxidase; ²Cholesterol oxidase-peroxidase; ³Synthetase-Oxidase-Peroxidase; ⁴Glycerol-3-oxidasa-peroxidase; ⁵β-hydroxybutyrate dehydrogenase; ⁶Urease-glutamate dehydrogenase; ⁷Copper salts in an alkaline medium; ⁸Ammonium molybdate-phosphomolybdate; ⁹Galactosidase-o-nitrophenyl-d-galactopyranose; ¹⁰Pyruvate kinase-phosphoenolpyruvate; ¹¹Magon sulfonate in alkaline solution; ¹²Mercuric thiocyanate-red ferric thiocyanate; ^aSpinreact., Girona, Spain; ^bRandox Laboratories., Northern Ireland, United Kingdom.

The precision and reliability of the techniques was controlled using lyophilized control serum (SPINTROL NORMAL 1002100; Spinreact., Girona, Spain) and (Assayed Multi-Sera AL 1027; Randox Laboratories., Northern Ireland, United Kingdom).

The provisions of the official standard (NMX-F-718-COFOCALEC, 2017) were followed. A total of 80 mL of milk in sterile urinalysis glasses (VAR-KS-409726-125; VIRESA., Mexico, Aguascalientes) were collected. Milk fat, milk protein, and fat/protein ratio were determined directly in each farm, using (EKOMILK ULTRA Analyzer Ultrasonic; BULTEH 2000., Zagora, Bulgaria), which uses low-power ultrasound (greater than 100 KHz), and low intensity (less than 1 W/cm²).

We processed the data using software SPSS (2013). All variables were tested for normality distribution (Shapiro-Wilk test) and homogeneity of variances (Levene test). The comparison between groups (Saanen vs. Nubian), and (high-yield goats vs. low-yield goats vs. dry period goats) was assessed using Analysis of Variance. A multiple comparison test of Tukey was performed when the effect of group. The linear relationships between the biochemical analytes were identified by the use a Pearson Correlation Coefficient matrix. Results were considered significant at (P<0.05).

RESULTS

The reference value and descriptive statistics for milk composition, GLU, COL, NEFA, TAG, β-HBA, BUN, ALB, GLOB, PROT-T, Ca²⁺, Pi, Na⁺, K⁺, Mg²⁺, and Cl^-, determined from metabolic profiles in goats, are shown in Table 2.

The biochemical profile results were consistent with the international literature for goats. All analytes except ALB and β-HBA showed racial differences (Table 3). The three milk variables registered a higher concentration in Nubian.

The comparison within breed by production group (high-yield vs. low-yield vs. dry period) showed differences in COL and β-HBA in both breeds (Table 4).

A negative correlation between GLU and NEFA was quantified. Positive correlations between NEFA with COL, TAG and β-HBA, between Ca²⁺ with Na⁺ and between K⁺ with Na⁺ and Mg²⁺ were quantified. Milk fat was correlated with COL, NEFA and β-HBA. Milk protein was correlated with BUN. The fat/protein ratio was correlated with COL and β-HBA.

Table 2
Mean (x), reference values, and confidence interval, for milk components and biochemical analytes in goats from Los Asmoles, Colima

	x ± SD	Reference	Confidence interval
Milk, n = 44 goats in production
Milk fat (g/100 mL of milk)	3.80±0.56	3.50±0.55a	3.63-3.97
Milk protein (g/100 mL of milk)	2.79±0.19	3.30±0.35a	2.73-2.84
Fat/protein ratio (g fat/g protein)	1.36±0.15	1.06±0.15a	1.31-1.40
Blood serum, n = 66 goats (44 goats in production + 22 goats in dry period)
Energy-lipid profile
Glucose (mM)	2.64±1.35	3.49±0.39b	2.30-2.97
Cholesterol (mM)	3.50±2.29	1.55±0.67b	2.94-4.06
Non-esterified fatty acids (mM)	0.26±0.01	0.30±0.10c	0.25-0.26
Triacylglycerol (mM)	0.22±0.05	0.20±0.10b	0.20-0.23
β-hydroxybutyrate (mM)	0.46±0.15	0.80±0.30c	0.42-0.50
Protein profile
Blood urea nitrogen (mM)	4.98±1.96	5.36±0.71b	4.49-5.46
Albumin (g/L)	34.01±5.36	33.00±3.30b	32.69-35.33
Globulin (g/L)	31.40±13.59	36.00±5.00b	28.06-34.74
Total protein (g/L)	70.41±14.05	69.00±4.80b	66.96-73.87
Mineral-electrolyte profile
Calcium ion (mM)	2.54±0.58	2.58±0.18b	2.40-2.69
Inorganic phosphate (mM)	4.07±0.54	4.62±0.25b	3.94-4.21
Sodium ion (mM)	140.16±10.87	150.00±3.10b	137.49-142.83
Potassium ion (mM)	4.14±1.70	4.30±0.50b	3.72-4.56
Magnesium ion (mM)	1.34±0.45	1.32±0.14b	1.23-1.45
Chloride ion (mM)	104.53±8.29	105.10±2.90b	102.49-106.57

• ^a
  (Prosser, 2021); ^b(Kaneko et al., 2008); ^c(Zamuner et al., 2020).

Table 3
Comparison of milk components and biochemical analytes between breed of goats

	Saanen	Nubian
	x ± SD
Milk, n = 22 goats in production/breed
Milk fat (g/100 mL of milk)	3.55±0.45b	4.06±0.55a
Milk protein (g/100 mL of milk)	2.71±0.16b	2.86±0.18a
Fat/protein ratio (g fat/g protein)	1.31±0.13b	1.41±0.16a
Blood serum, n = 33 goats/breed (22 goats in production/breed + 11 goats in dry period/breed)
Energy-lipid profile
Glucose (mM)	1.96±1.21b	3.31±1.16a
Cholesterol (mM)	2.38±1.64b	4.62±2.32a
Non-esterified fatty acids (mM)	0.25±0.007b	0.26±0.010a
Triacylglycerol (mM)	0.18±0.05b	0.25±0.03a
β-hydroxybutyrate (mM)	0.45±0.15a	0.46±0.16a
Protein profile
Blood urea nitrogen (mM)	3.93±1.18b	6.02±2.05a
Albumin (g/L)	33.74±4.02a	34.27±6.49a
Globulin (g/L)	24.69±12.16b	38.11±11.60a
Total protein (g/L)	63.44±10.47b	77.39±13.82a
Mineral-electrolyte profile
Calcium ion (mM)	2.39±0.67b	2.70±0.43a
Inorganic phosphate (mM)	3.76±0.29b	4.39±0.56a
Sodium ion (mM)	134.39±8.23b	145.93±10.18a
Potassium ion (mM)	3.16±1.83b	5.12±0.76a
Magnesium ion (mM)	1.08±0.35b	1.60±0.40a
Chloride ion (mM)	100.33±4.30b	108.72±9.21a

• Significant differences were obtained between the groups indicated with different letters (P<0.05).

Table 4
Comparison of milk components and biochemical analytes within breed by production group

	Saanen			Nubian
	High-yield	Low-yield	Dry period	High-yield	Low-yield	Dry period
Milk, n = 22 goats in production/breed (11 high-yield goats/breed, 11 low-yield goats/breed)
Milk fat	3.60±0.42a	3.50±0.49a		4.19±0.54a	3.92±0.55a
Milk protein	2.65±0.15a	2.76±0.16a		2.86±0.20a	2.87±0.17a
Fat/protein ratio	1.35±0.13a	1.26±0.11a		1.46±0.15a	1.36±0.16a
Blood serum, n = 33 goats/breed (11 high-yield goats/breed, 11 low-yield goats/breed, 11 dry period goats/breed)
Energy-lipid profile
GLU (mM)	2.14±1.03a	2.11±1.35a	1.64±1.27a	3.21±1.26a	3.31±1.01a	3.40±1.28a
COL (mM)	3.09±1.45a	2.87±1.49a	1.16±1.34b	5.83±1.71a	5.71±1.99a	2.33±1.32b
NEFA (mM)	0.25±0.007a	0.25±0.004a	0.25±0.007a	0.27±0.01a	0.26±0.01a	0.26±0.01a
TAG (mM)	0.18±0.04a	0.19±0.05a	0.18±0.06a	0.24±0.04a	0.25±0.02a	0.26±0.01a
β-HBA (mM)	0.53±0.11a	0.46±0.16ª,b	0.36±0.13b	0.58±0.12a	0.41±0.13ª,b	0.41±0.16b
Protein profile
BUN (mM)	4.07±1.17a	3.83±1.47a	3.90±0.95a	6.23±2.08a	5.75±1.66a	6.08±2.50a
ALB (g/L)	34.54±3.23a	33.75±5.26a	32.93±3.49a	36.57±7.49a	33.79±4.65a	32.46±6.88a
GLOB (g/L)	26.45±10.39a	26.19±13.59a	21.44±12.76a	37.17±12.66a	38.10±10.15a	39.06±12.86a
PROT-T (g/L)	66.00±9.27a	64.94±11.18a	59.38±10.57a	78.74±14.42a	76.89±12.21a	76.53±15.85a
Mineral-electrolyte profile
Ca2+ (mM)	2.45±0.58a	2.47±0.71a	2.25±0.74a	2.75±0.63a	2.74±0.37a	2.61±0.23a
Pi (mM)	3.65±0.31a	3.79±0.18a	3.84±0.35a	4.53±0.58a	4.30±0.53a	4.32±0.60a
Na+ (mM)	133.37±9.40a	133.23±6.51a	136.57±8.84a	144.57±10.68a	143.34±6.65a	149.89±12.12a
K+ (mM)	3.05±1.84a	2.83±1.35a	3.61±2.27a	4.93±1.20a	5.14±0.41a	5.30±0.40a
Mg2+ (mM)	1.10±0.38a	1.00±0.22a	1.14±0.43a	1.59±0.32a	1.55±0.36a	1.66±0.53a
Cl- (mM)	99.32±4.60ª	98.84±2.78a	102.83±4.46a	111.32±9.75a	107.83±9.59a	107.00±8.53a

• Milk fat (g/100 mL of milk), milk protein (g/100 mL of milk), fat/protein ratio (g fat/g protein); glucose (GLU), cholesterol (COL), non-esterified fatty acids (NEFA), triacylglycerol (TAG), β-hydroxybutyrate (β-HBA), blood urea nitrogen (BUN), albumin (ALB), globulin (GLOB), total protein (PROT-T), calcium ion (Ca²⁺), inorganic phosphate (Pi), sodium ion (Na⁺), potassium ion (K⁺), magnesium ion (Mg²⁺), and chloride ion (Cl^-); significant differences were obtained between the groups indicated with different letters (P<0.05). All data are presented by mean ± SD.

DISCUSSION

The milk variables (Table 3) showed a higher concentration in Nubian goats. Clark and Mora (2017) reported that the concentration of milk fat and milk protein in Saanen goats is 3.3 g/100 mL of milk and 2.8 g/100mL of milk, respectively. Values consistent with our study. Nubian goat milk has a concentration of 4.5g/100mL of milk and 3.7g/100mL of milk, for milk fat and milk protein respectively (Moatsou and Park, 2017). Therefore, a value for milk protein (2.86 ± 0.18g/100mL of milk) was identified slightly lower than the report in the international literature.

Henna et al. (2021) indicated that COL increases in the postpartum period proportionally to milk production. Behavior consistent with our study in dry period (Table 4). β-HBA is a ketone body used for additional energy in ruminants (Benedet et al., 2019), especially at the beginning of lactation (Zamuner et al., 2020). Therefore, in high-yield goats its concentration is higher compared to goats in dry period (Reese et al., 2020).

Zamuner et al. (2020) observed a correlation between NEFA and β-HBA (r = 0.66), and between NEFA and GLU (r = -0.46) in dairy goats. Additionally, correlations between NEFA and β-HBA have been reported in goats during the last week of gestation (r = 0.45), and in periparturient dairy ewes (r = 0.41) (Karagiannis et al., 2014; Radin et al., 2015). Values consistent with our study (Table 5).

Table 5
Pearson correlation coefficient for different biochemical analytes in Saanen and Nubian goats from Los Asmoles, Colima (n = 66 blood serum)

	COL	NEFA	TAG	β-HBA	BUN	ALB	GLOB	PROT-T	Ca2+	Pi	Na+	K+	Mg2+	Cl-
GLU	0.26	-0.37*	0.25	0.15	0.26	0.11	0.10	0.12	0.25	0.12	0.26	0.13	0.24	0.27
	COL	0.46*	0.21	0.21	0.29	0.23	0.16	0.13	0.10	0.23	0.24	0.19	0.28	0.16
		NEFA	0.39*	0.47*	0.21	0.25	0.27	0.13	0.20	0.12	0.22	0.11	0.12	0.10
			TAG	0.21	0.28	0.05	0.15	0.11	0.12	0.18	0.16	0.14	0.20	0.21
				β-HBA	0.13	0.25	0.05	0.12	0.08	0.18	0.16	0.09	0.08	0.17
					BUN	0.29	0.26	0.16	0.20	0.24	0.19	0.18	0.14	0.11
						ALB	0.29	0.27	0.18	0.18	0.05	0.23	0.25	0.15
							GLOB	0.26	0.15	0.12	0.06	0.23	0.24	0.17
								PROT-T	0.10	0.15	0.12	0.13	0.14	0.13
									Ca2+	0.12	0.47*	0.16	0.19	0.20
										Pi	0.16	0.16	0.18	0.22
											Na+	0.41*	0.16	0.12
												K+	0.47*	0.11
													Mg2+	0.22
														Cl-

• Glucose (GLU), cholesterol (COL), non-esterified fatty acids (NEFA), triacylglycerol (TAG), β-hydroxybutyrate (β-HBA), blood urea nitrogen (BUN), albumin (ALB), globulin (GLOB), total protein (PROT-T), calcium ion (Ca²⁺), inorganic phosphate (Pi), sodium ion (Na⁺), potassium ion (K⁺), magnesium ion (Mg²⁺), and chloride ion (Cl^-); *P<0.05.

The correlations observed between NEFA and β-HBA, and between NEFA and GLU raise the possibility of combining their results to estimate the lipid metabolic rate in dairy goats (Reese et al., 2020). Low levels of Mg²⁺ result in low levels of K⁺ and Na⁺ (Table 5). Additionally, a reduction in Na⁺ could cause a reduction in Ca²⁺ (Abdelrahman et al., 2002). Values consistent with our study.

The correlation between milk fat and β-HBA in dairy goats (Table 6) describes the importance of this ketone body in the synthesis of milk fat (Akkaya et al., 2020), mainly in the esterification of saturated fatty acids.

Elongation beyond 16 carbons is not possible in the ruminant mammary gland (Martínez and Suárez, 2018; Chandel, 2021). Additionally, the expression of genes related to TAG desaturation for fatty acid elongation is reduced (Henna et al., 2021). Therefore, the very long carbon chain fatty acids from dairy fat come from COL (esterified and free) and NEFA (Reese et al., 2020). Values consistent with our study (Table 6). The BUN passes from blood to body tissues that contain water (Menzies, 2021). Therefore, BUN passes from blood to mammary gland and increases milk protein (Soria et al., 2019). Finally, the results suggest that COL and β-HBA are subordinate analytes of the fat/protein ratio since it increases as COL and β-HBA also increase.

Table 6
Correlations between milk components and biochemical analytes n = 44 goats in production

	Milk fat	Milk protein	Fat/protein ratio
Blood serum
Energy-lipid profile
Glucose (mM)	0.19	0.14	0.15
Cholesterol (mM)	0.69***	0.14	0.44**
Non-esterified fatty acids (mM)	0.34*	0.19	0.12
Triacylglycerol (mM)	0.14	0.12	0.11
β-hydroxybutyrate (mM)	0.32*	0.01	0.35*
Protein profile
Blood urea nitrogen (mM)	0.12	0.49**	0.15
Albumin (g/L)	0.01	0.09	0.06
Globulin (g/L)	0.19	0.14	0.12
Total protein (g/L)	0.13	0.19	0.16
Mineral-electrolyte profile
Calcium ion (mM)	0.16	0.12	0.15
Inorganic phosphate (mM)	0.10	0.14	0.14
Sodium ion (mM)	0.10	0.13	0.16
Potassium ion (mM)	0.19	0.13	0.12
Magnesium ion (mM)	0.15	0.12	0.11
Chloride ion (mM)	0.12	0.13	0.14

• Milk fat (g/100 mL of milk), milk protein (g/100 mL of milk), fat/protein ratio (g fat/g protein); *P<0.05; **P<0.01; ***P<0.001.

CONCLUSIONS

Results provide insight into metabolic adaptations in lactation and identify links between key analytes and milk fat/protein in goats. The calculated confidence intervals could be used to detect alert situations when at least 5% of the sampled goats would fall outside of the calculated reference interval for a given parameter.

ACKNOWLEDGMENTS

This project was supported by the National Council for the Humanities, Sciences and Technology-México (CONAHCYT-México) and the Network Advances in Agricultural Research in Mexico.

REFERENCES

• ABDELRAHMAN, M.N.; ABO-SHEHADA, M.N.; MESANAT, A.; MUKBEL, R. The requirements of calcium by Awassi ewes at early lactation. Small Ruminant Res., v.45, p.101-107, 2002.
• AKKAYA, F.; SENTURK, S.; MECITOĞLU, Z. et al. Evaluation of metabolic profiles of Saanen goats in the transition period. J. Hell. Vet. Med., v.71. p.2127-2134, 2020.
• BAUMAN, D.E.; MATHER, I.H.; WALL, R.J.; LOCK, A.L. Major advances associated with the biosynthesis of milk. J. Dairy Sci., v.89, p.1235-1243, 2006.
• BENEDET, A.; MANUELIAN, C.L.; ZIDI, A. et al. Invited review: beta-hydroxybutyrate concentration in blood and milk and its associations with cow performance. Animal, v.13, p.1676-1689, 2019.
• CHANDEL, N.S. Lipid metabolism. Cold Spring Harb. Perspect. Biol., v.13, p.34-41, 2021.
• CLARK, S.; MORA, G.M.B. A 100-year review: Advances in goat milk research. J Dairy Sci., v.100, p.10026-10044, 2017.
• FRASER, M.D.; VALLIN, H.E.; ROBERTS, B.P. Animal board invited review: Grassland-based livestock farming and biodiversity. Animal, v.16, p100671, 2022.
• HENNA, K.; BOUDJELLBA, S.; KHAMMAR, F. et al. Endocrine, energy, and lipid status during parturition and early lactation in indigenous goats native to the Algerian Sahara. Vet. World, v.14, p.2419-2426, 2021.
• KANEKO, J.J.; HARVEY, W.J.; BRUSS, L.M. Appendix 8 blood analyte reference values in large animals. In: _____. (Eds.). Clinical biochemistry of domestic animals. California: Academic Press, 2008. p.882-888.
• KARAGIANNIS, I.; PANOUSIS, N.; KIOSSIS, E. et al. Associations of pre-lambing body condition score and serum β-hydroxybutyric acid and non-esterified fatty acids concentrations with periparturient health of Chios dairy ewes. Small Ruminant Res., v.120, p.164-173, 2014.
• LIMA, A.R.C.; SILVEIRA, R.M.S.; CASTRO, M.S.M. et al. Relationship between thermal environment, thermoregulatory responses and energy metabolism in goats: a comprehensive review. J. Therm. Biol., v.109, p103324, 2022.
• MARKETS and statistics. Mexico: Canilec/National Chamber of Industrial Milk, 2023. Available in: http://www.canilec.org.mx/index.html Accessed in: 27 Mar. 2023.
  » http://www.canilec.org.mx/index.html
• MARTÍNEZ, G.M.; SUÁREZ, V.H. The mammary gland: morphology and development. Synthesis of milk components. In: _____. (Eds.). Goat dairying: production, management, health, quality of milk and products. Buenos Aires, Argentina: Inta, 2018. p.37-41.
• MENZIES, P. Udder health for dairy goats. Vet. Clin. North Am. Food Anim. Pract., v.37, p.149-174, 2021.
• MOATSOU, G.; PARK, W.Y. Goat milk products: types of products, manufacturing technology, chemical composition, and marketing. In: PARK, W.Y.; HAENLEIN, F.W.G.; WENDORFF, L.W. (Eds.). Handbook of milk of non-bovine mammals. Oxford, United Kingdon: John Wiley & Sons, 2017. p.84-139.
• NAYIK, G.A.; JAGDAE, Y.D.; GAIKWAD, S.A. et al. Recent insights into processing approaches and potential health benefits of goat milk and its products: a review. Front. Nutr. v.8. p 789117, 2021.
• NMX-F-718-COFOCALEC. Milk product system - food - dairy - milk and milk products - sampling guide. Council for the promotion of the quality of milk and its derivatives. 2017. Available in: http://diariooficial.gob.mx/ normasOficiales.php Accessed in: 27 Mar. 2023.
  » http://diariooficial.gob.mx/ normasOficiales.php
• PAYNE, J.M. The Future of presymptomatic diagnosis: the compton metabolic profile test. Proc. R. Soc. Med., v.65, p.181-183, 1972.
• PEEL, M.C.; FINLAYSON, B.L.; MCMAHON, T.A. Updated world map of the Köppen-Geiger climate classification. Hydrol. Earth Syst. Sci., v.1, p.1633-1644, 2007.
• PROSSER, C.G. Compositional and functional characteristics of goat milk and relevance as a base for infant formula. J. Food Sci., v.86, p.257-265, 2021.
• RADIN, L.; SIMPRAGA, M.; VINCE, S. et al. Metabolic and oxidative status of Saanen goats of different parity during the peripartum period. J. Dairy Res., v.82, p.426-433, 2015.
• REESE, O.W. et al. Mammary gland (mamma, uber, mastos). In: KÖNIG, H.E.; LIEBICH, G.G., (Eds.). Veterinary anatomy of domestic animals. Stuttgart, Germany: Georg Thieme Verlag KG, 2020. p.642-648.
• SORIA, L.R.; NITZAHN, M.; ANGELIS, A. et al. Hepatic glutamine synthetase augmentation enhances ammonia detoxification. J. Inherit. Metab. Dis., v.42, p.1128-1135, 2019.
• SPSS statistics user’s guide. Version 22.0. Armonk: IBM Corp., 2013.
• STATISTICAL and geographical yearbook of Colima. Colima, Mexico: National Institute of Statistic and Geography, 2023. Available in: https://www.inegi.org.mx/COL_ANUARIO_PDF.pdf Accessed in: 27 Mar. 2023.
  » https://www.inegi.org.mx/COL_ANUARIO_PDF.pdf
• ZAMUNER, F.; DIGIACOMO, K.; CAMERON, A.W.N.; LEURY, B.J. Short communication: associations between nonesterified fatty acids, β-hydroxybutyrate, and glucose in periparturient dairy goats. J. Dairy Sci., v.103, p.6672-6678, 2020.

Publication Dates

• Publication in this collection
  27 Jan 2025
• Date of issue
  Jan-Feb 2025

History

• Received
  28 Mar 2024
• Accepted
  15 June 2024