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Recent advances in exploiting goat\'s milk: quality, safety and production aspects. Nissim Silanikove , Agricultural Research Organization ( ARO ), Institute of Animal Science, Israel. Gabriel Leitner , The Veterinary Institute, Israel.

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Recent advances in exploiting goat\'s milk: quality, safety and production aspects

Nissim Silanikove, Agricultural Research Organization (ARO), Institute of Animal Science, Israel.

Gabriel Leitner, The Veterinary Institute, Israel

Uzi Merin, ARO, Israel; Colin .G. Prosser, Dairy Goat Co-operative (N.Z.) Ltd., Hamilton, New Zealand




herding of goats is thought to have evolved about 10 000 years in persia
Herding of goats is thought to have evolved about 10,000 years in Persia
  • Goat milk, and the cheese made from it, were venerated in ancient Egypt with some Pharaohs supposedly having these foods placed among the other treasures in their burial tombs (Smith, 2006). Goat milk continued to play an important role in human nutrition in areas acknowledged as the cradle of modern civilization (Hatziminaoglou and Boyazoglu, 2004).

What makes goat milk an attractive option?

  • High quality source of protein, minerals and vitamins just like cow milk(soy provides protein only)
  • Differs from cow milk
    • Casein protein profile better for infant digestion
    • More medium chain fatty acids, which are easier to absorb
    • Naturally high in bioactives that are important for infant growth and development
amino acid pattern compared to human milk
Amino acid pattern compared to human milk

Goat milk protein has similar amino acid profile to human milk protein

Rutherfurd et al (2008) Int J Food Sci Nutr Jun18

casein profile of goat milk
Casein profile of goat milk
  • Goat casein profile closer to human milk:
  • Low levels of αs1-casein
  • Greater proportion of β-casein
  • Formation of a finer curd - Easier digestion
  • Lower allergenic burden
fatty acids in goat milk
Fatty acids in goat milk
  • More medium chain fatty acids
    • Have anti-viral activity
    • Absorbed more rapidly than other saturated fatty acids
    • Do not form hard stools
bioactive components
Bioactive Components
  • Goat milk is a natural source of bioactive components such as:
    • Nucleotides,
    • Polyamines,
    • Free amino acids
  • These bioactives are all part of the Non-Protein Nitrogen (NPN) fraction of milk
  • They are the subject of increased interest and research
  • Nucleotides are building blocks of DNA & RNA
  • They play a role in gastrointestinal health, maturation and recovery
  • Considered to be ‘conditionally essential’ for proper development in infants as they cannot synthesize enough for growing tissue
  • Can be added to infant formula
  • Total nucleotide levels naturally higher in goat milk than cow milk (absent in soy)

Total Nucleotides

Prosser et al (2008) Int J Food Sci Nutr 59:123-133

  • Essential for intestinal cell growth and development of digestive capacity
  • May help to prevent or reduce sensitisation to food allergens
  • Total polyamine concentration naturally present in goat milk is higher than cow milk

(Prosser et al 2008, Int J Food Sci Nutr 59:123-133)

free amino acids
Free amino acids
  • Important for gut health and immunity
  • Taurine
    • Bile salt formation,
    • Immune function
    • Some infants may become deficient in taurine, so is often added to infant formula
  • Glutamic acid – source of energy for gut
  • Levels of these amino acids naturally higher in goat milk than cow milk
free amino acids1
Free amino acids

Prosser et al 2008, Int J Food Sci Nutr 59:123-133

nutrient utilisation
Nutrient utilisation
  • Studies show that goat milk fat is utilised more efficiently than cow milk fat
    • in animals with short bowel syndrome (Alfrerez et al, 2001)
    • in infants with malabsorption syndrome (Hachelef et al, 1993)
  • May be due to higher amounts of medium chain fatty acids
  • These studies suggest that goat milk could be a useful dietary intervention for human malabsorption syndrome.
nutrient utilisation1
Nutrient utilisation
  • Similar studies suggest mineral uptake from goat milk greater than cow milk
    • Calcium uptake and calcium content of femur, sternum and Longissimus dorsi muscle in rats (Aliaga L, et al 2000; Campos et al, 2003).
    • Uptake and utilisation of iron (Park et al, 1986; Aliaga et al, 2000; Barrionuevo et al, 2002; Alferez et al, 2006), copper (Barrionuevo et al, 2002), zinc and selenium (Alferez et al, 2003) in rats.
    • Sustains high calcium and magnesium uptake in anemic animals (Nestares et al, 2008)
    • Bone mineral density in growing pigs (Murry et al, 1998)
  • Mechanism for this effect is not known
  • Studies show goat milk forms a finer curd than cow milk when acidified in the stomach (Jenness 1980, Haenlein 1992)
  • Low αs1-casein is considered a key reason for this (Clark & Sherbon, 2000)
    • NZ goat milk has low αs1-casein
  • Softer curd thought to facilitate digestion
  • Almass et al (2006) confirms that goat milk proteins digested faster than cow milk proteins
gut health
Gut health
  • Good gut health important for digestion and nutrient absorption
  • Infant gut is relatively immature and more ‘leaky’ than adult gut
  • Gut leakiness linked to several disorders, including allergy
  • Does goat milk enhance gut health?

Healthy gut

Normal IntestineNormal permeability

“Leaky Intestine”Increased permeability




Normal diet

7 days

+goat milk

7 days

Trial Details



treatment heat stress
Treatment = heat stress

heat = more leaky

heat + Goat milk = less leaky

Prosser et al, 2004, J Appl Physiol96:650-654


Control - healthy


+ goat milk


Intestinal Villi protected by goat milk

auckland infant growth study
Auckland infant growth study

A randomised, double-blind comparison of goat and cow infant formula

Cameron Grant, Barbara Rotherham, Sue Sharpe, Robert Scragg, John Thompson, John Andrews, Clare Wall, Judith Murphy. Dianne Lowry

University of Auckland

Starship Children’s Hospital, Auckland

Sponsored by Dairy Goat Co-operative (N.Z.) Ltd, Hamilton

Published in J Pediatrics Child Health, 41, 564-568

key conclusions
Key conclusions
  • Growth of infants fed goat infant formula is the same as infants fed cow formula
  • Growth of infants fed goat infant formula is similar to breast fed infants
  • Tolerability of goat infant formula is similar to cow infant formula
  • Goat infant formula is a safe and effective source of nutrition for infants

Relationships between the conditions of goat\'s milk production and the contents of some components of nutritional interest in Rocamadour cheese. A. Lucas et al SRR, 2008 - France

milk fatty acid composition of goats grazing on alpine pasture an et al srr 2006 slovenia
Milk fatty acid composition of goats grazing on alpine pasture: Žan et al., SRR, 2006 - Slovenia
  • Given free choice, consumption of browse material would be higher in goats than in sheep and cattle, re-emphasizing our null hypothesize that the main advantage of goats over other ruminant species in producing milk rich in valuable nutritional sources relates to its unique feeding habit and high digestion capabilities.
  • Goats milk on pasture is naturally enriched in fat soluble vitamins, unsaturated fatty acids and CLA, in addition to being naturally rich in medium-chain fatty acids.
  • Furthermore, goats milk on pasture have an improved profile of medium-chain fatty acids, in comparison to goats fed conventional concentrate-forage diets
  • High-alpine pasture was shown to be more effective than low-land alpine pasture in this regard.
  • Thus, milk from goats feeding on pasture may present an overlooked "treasure trove" with respects to its health promoting lipid profile.
  • However, a deeper understanding of the interactions between lipids and non-lipid components of pasture and milk composition is needed.
goats on scrubland and woodland
Goats on scrubland and woodland
  • Goats are able to consume as much as 10 g/day of hydrolysable tannins and 100-150 g/day of condensed tannins without evidence of toxicity (Silanikove et al., 1996, SRR).
  • This ability to ingest tannins exceeds the capacity of sheep and cattle, which indeed are not able to survive without considerable supplementation on such grazing land (Silanikove, 2000, SRR; Silanikove et al., 2001, AFST).
  • Detoxification of tannins by goats is based on enzymatic hydrolysis and depolymerization of the ingested tannins (Silanikove, et al., 2001, SRR).
  • Thus, theoretically, large amount of hydrolysable and condensed tannins-derived phenols as well as of other types of phenolic compounds are absorbed from the GIT by browsing goats
goats on scrubland and woodland1
Goats on scrubland and woodland
  • Plants produce an enormous array of secondary metabolites; many of them has biological effects when comsumed by humans.
  • In particular, monoterpens were identified as compounds that greatly influence the aroma of milk.
  • High content of phenols in milk has shown to improve the quality of milk, such as its oxidative stability and the processing efficiency and quality of dairy products.
  • The results of a few recent studies demonstrate the accumulation of various phenolic compounds in the milk of grazing goats).
  • Whereas this proposition is still speculative, in our view, goat milk rich in phenolic compounds derived from the diet represents a ‘treasure trove’ of potential opportunities for developing functional foods
food safety
Food Safety
  • When considering food safety, the major aspects usually thought of are:
  • i) Milk as a source of infection by zoonoses (defined as pathogens which may be transferred from an infected animal to humans and thereby causes a disease in the infected humans);
  • ii) Milk as a source of pathogens that produce toxins, thereby, affecting all organisms, including humans;
  • iii) Milk as a source of undesirable substances from the animal’s diet or inappropriate use of antibiotic, disinfecting and cleansing substances, etc.
food safety1
Food Safety
  • In Europe and the USA, the main regulatory mean to prevent the occurrence of zoonoses and other pathogenic bacteria and their toxins in marketed goat milk is through bacterial count of the raw milk (Pirisi et al., 2007, SRR).
  • Based on the potential pathogenic issues (written review) there is a reason to implement more stringent food-safety control system in the dairy goat industry.
  • Adding the counts of psychrotrophs may be a valuable criterion not only for the evaluation of milk storage conditions, but for the likelihood of its contamination with pathogens.
  • Another feasible means to improve milk hygiene is to include somatic cell count in milk grading in the form of a payment scheme

Somatic cell count and gross composition as bases

for grading milk quality in sheep and goats


Aim: to calculate the losses of milk and cheese loss as

related to the level of subclinical udder infection in a herd.

Elucidated the major factors that influence milk yield and,

consequently, curd yield in Assaf sheep and Saanen and

Shami × Anglo-Nubian goats,


Quantifying the damage caused by IMI with CNS

From data collected in the present study and those published recently

two equations could be developed to calculate milk yield loss and

total curd yield loss.

These equations combine milk loss and reduction in curd yield per liter of

milk in sheep or goats with sub clinical IMI:

Milk yield loss (%) = 100 - [C × 100 + (100-C) × IUY]/100

Total curd yield loss (%) = 100 - [C × 100 + (100-C) × (IUY-ICY × D)]/100

where: C = % uninfected udders;

IUY = percentage to which milk production is reduced

by sub clinical udder infection;

ICY = percentage of curd lost because of sub clinical udder


D = liters of milk needed to produce 1 kg of cheese

(30 %moister)


The Negative Feedback Mechanism Flow-Chart: The ARO concept.

Blue arrows denote flow of signal along the feedback loop, red arrows denote positive effect and black arrows denote suppressive effect

milking frequency and goats milk production
Milking frequency and goats milk production
  • Once-daily milking is more of a traditional milking routine for goats in Europe and in Asia Minor, than sheep and cows.
  • The use of this system in goat farms reflect the fact that many of the farmers devote a large proportion of their activities to producing and selling dairy products (mainly cheese), as an important part of their income.
  • Small difference between once-daily and twice-daily milking regimens which were found in low to moderate producing goats relates to a high udder volume of the goat, in particular with large cisternal capacity that allows a continuous drop of alveolar milk and therefore delays the effect of the intramammary feedback inhibition.
  • This between- and within-species variability in response to milking frequency may be explained in light of the plasmin-related MBNF regulatory concept.
my 1932 kg days in milk 365 d fat 3 1 protein 2 7
MY= 1932 kg; days in milk 365 d; fat = 3.1%, Protein = 2.7%
  • Ideal goat for intensive management - twice a day milking

Cork 2005

Milk quantity:

Yield of milk, fat, total proteins,

casein and curd.

Milk quality:

Internal bacterial contamination,

somatic cell count,

secreted enzymes.


Cork 2005

Bacterial infection may affect

caseinolysis and micelle properties

by three main routes:

1. directly, by secreting extracellular enzymes

different bacteria will cause different "type"

of physico-chemical damage to the milk


Cork 2005

2. activate the host innate immune system

milk from different type of bacteria with similar

SCC will result in similar damage to the milk

3. a combination of 1 and 2

Model that explains the interrelationships between bacterial infection and deterioration in milk quality

Bacterial infection

Activation of the

innate system





Oxidatiive response by O2, NO, H2O2,O2

via XO, LPO







of casein




Cork 2005



Infected gland

~ 3,000,000

Cell depended

Healthy gland

~ 50,000 Cows

~ 300,000 goats and sheep

Bacteria and Cells depended


The LS Means of CMT and log SCC in uninfected and infected

udders and their different significance level (P [F]).


Lactose concentration: sheep or goat with one

gland infected with CNS specie and the

contra-lateral being free

Sheep - 25.1%, P < 0.0001

Goat - 11.3%, P < 0.004

Lactose, g/L

Milk yield (half) of sheep or goat infected with CNS specie in one gland and the contra-lateral being free.Open bars – S; Hatched bars – G

The ratio in the reduction in milk yield between

goats and sheep in comparison to the ratio of

reduction in lactose concentration

  • The greater reduction in lactose concentration in infected glands of sheep than in goats, explains the higher loss of milk yield in sheep

Fat concentration: sheep or goat with one gland infected with CNS specie and the

contra-lateral being free

Sheep - 5%, NS

Goat - 0.03%, NS

fat, g/L


Protein concentration: sheep or goat with one gland infected with CNS specie

and the contra-lateral being free

Sheep - 9%, P < 0.0009

Goat + 2.3%, P <0.07

protein, g/L


Casein concentration: sheep or goat with one gland infected with CNS specie

and the contra-lateral being free

Sheep - 12%, P < 0.0002

Goat + 0.003%, NS

casein , g/L


Whey concentration: sheep or goat with one gland infected with CNS specie

and the contra-lateral being free

Sheep + 7.5%, P < 0.07

Goat +11.5%, P < 0.0001

Whey, g/L

  • In goats the increase in total protein concentration relates to increase in total whey concentration
  • In sheep the reduction in total protein concentration relates to a decrease in casein concentration, which overweighs the increase in whey concentration

Proteose-peptone concentration: sheep or goat with one gland infected with CNS specie

and the contra-lateral being free

Sheep + 247%, P < 0.0001

Goat +151%, P < 0.0001

P-p, g/L


Ca activity: sheep or goat with one gland infected with CNS specie and the

contra-lateral being free

Sheep - 30.1%, P < 0.002

Goat -14.2%, P < 0.002

Ca, mmol

  • The basal level of PL activity is higher in sheep than in goats, which explains the higher basal level of proteose-peptones
  • PL activity in infected glands is higher in sheep than in goats, which explain the higher increase in proteose-peptones
  • In sheep, the source of increased PL activity in the infected gland is accelerated conversion of plasminogen to plasmin, whereas in goats the source is external
Question: How comes that in goats accelerated degradation of casein is not reflected in casein concentration, whereas in sheep it does?
  • Answer: In goats the reduction in casein output (30%) is essentially similar to the reduction in milk yield, whereas in sheep the reduction in casein output (60%) is higher than in milk volume (53%).
  • Thus, both in goats and sheep part of the increased loss in casein yield is related to increased degradation of casein











SDS PAGE Tricine

milk production general conclusions
Milk production: General conclusions
  • goats appear to be the least affected ruminant species in respect to physiological manipulations (lower milking frequency), IMI and environmental or emotional stresses that reduce milk secretion.
  • These advantages are explained by their unique morphophological and physiological features and the above-described plasmin-related MBNF.
in goat we trust
In Goat we trust

Irrespective to our origin, We hope that this lecture provide strong case that the goats dairy industry has a bright future