Composition Of Sheep Milk Research Articles

Milk yield and chemical composition of sheep milk in Srednostaroplaninska and Tetevenska breeds

The study was conducted from April to July on pastures located at different altitudes and of different sward composition during the milking period of Srednostaroplaninska and Tetevenska sheep. Morning bulk milk was sampled for analysis monthly between April and end of July. The purpose of the study was to establish the milk yield and to investigate the chemical composition of sheep milk obtained from Srednostaroplaninska and Tetevenska breeds reared on pastures at a different altitude and with different sward composition. The Tetevenska breed had a higher daily milk yield and exhibited a high percentage of casein in milk, while the milk from Srednostaroplaninska sheep had a higher content of macro elements - calcium, potassium, magnesium and some trace elements (iron and manganese). The milk fat content, including the percentages of saturated and unsaturated fatty acids in milk obtained from studied breeds, was similar. There was a tendency towards higher percentage of polyunsaturated and long-chain fatty acids in the milk of Srednostaroplaninska sheep, reared on mat grass pastures. Milk casein content was higher in the milk of Tetevenska sheep, as well as the content of non-essential amino acids as compared to Srednostaroplaninska sheep.

A study effect of age of dam and sex of birth on chemical and physical composition of milk in some farm animals

This study was carried out at AL-Qadisiya Governorate/ AL-Shinafia district during a period from July- September 2010 to evaluate the effect of age of dam and sex of birth on physico-chemical composition of milk in some farm animals(cows ,sheep and goats). by using ultra-sonic milk Analyzer to analysis of physico-chemical composition of milk. A total of (153) samples of milk were used in this study distributed in to (54) samples for cows, (53) samples for sheep and (46) samples for goats. These samples were collected from animals directly and kept in ice box during transportation to the laboratory to analysis. Results of this study showed that milk of sheep and goats didn’t differ significantly as compared with cows milk in (PH, Density, Solid not fat).But differed significantly (P˂0.05) in other components. The study revealed that sheep milk contain the highest Ash(0.74%) while cow milk had lactose (4.25%) , but goat milk had the highest solid not fat (8.27%) and protein (3.37%). The study showed that there was no significant effect of sex of birth on physico-chemical composition of milk of cows, sheep and goats with exception the effect of it on lactose percentage in sheep. Age of dam didn’t effect on most physico-chemical composition of milk of cow and goat and some chemical composition of sheep milk (Ash and Fat).

Effect of day length and exogenous melatonin on chemical composition of sheep milk

Abstract. Changes in day length are a major factor in the productivity of farm animals showing reproductive seasonality. Parameters of milk production in sheep and goats are dependent on melatonin and prolactin concentrations. Changes in the prolactin secretion in lactating sheep have an effect on the amount of milk produced, synthesis of milk proteins, fat and immunoglobulins (i.e. milk composition). In the end the quality and commercial value of milk is determined as well. The aim of this study was therefore to find out the effect of day length and exogenous melatonin on the chemical composition of milk and the level of fatty acids. Subjects were 60 Polish Longwool Sheep. Animals were randomly assigned to three groups, Group I (n=20) – ewes raised under natural day length; Group II (n=20) ewes raised under natural day length and were implanted with melatonin; Group III (n=20) – ewes exposed to an artificially short photoperiod (16D:8L). Sheep were milked twice daily using the Alfa Laval Agri milking machine. Composite milk samples were collected every 28 days to determine chemical composition and fatty acid content. The results obtained showed that the administration of exogenous melatonin and the simulation of a short-day photoperiod during the summer period had significant effects on the milk levels of solids, protein, fat and lactose, and on the fatty acid content of sheep milk.

Yield of cheese and sheep milk composition from synthetic population of Bulgarian dairy and East-Friesian breed

Comparison between Synthetic population Bulgarian milk (SPBM) and East-Friesian (EF) sheep was done for laboratory yield of cheese and milk composition. The comparison of the means for the individual laboratory yield of cheese showed significantly higher values in the ewes of SPBM on first lactation (2,4735 g) compared to the EF breed (1,7608 g), (P<0,001). The higher amount of cheese probably was connected with the tendency for higher content of the fat, protein and dry matter. However on the second lactation the two breeds showed the same values: SPBM 1,9370 g and EF breed 1,9282 g. No significant differences in the quantity of milk and its composition between the sheep on first and second lactation were observed for both breeds.

Identification of single nucleotide polymorphisms in the ovine acetyl-CoA carboxylase-alpha gene

Acetyl-CoA carboxylase (ACACA) is the rate-limiting enzyme in the biosynthesis of palmitic acid and long-chain fatty acids. The dietary intake of palmitic acid, which represents approximately 22% of sheep milk fatty acids, increases low-density lipoprotein (LDL) levels and the risk of developing human cardiovascular diseases. Following the candidate gene approach for improving sheep milk composition, and as a first step in assessing the possible influence of the ovine ACACA gene on milk fatty acid composition and its potential use as an animal genetic model of human atherosclerosis disease, we present here an investigation into the genetic variability of the ovine ACACA gene. We sequenced approximately 6.6 kb of ovine ACACA cDNA, including most of the coding sequence of the protein (except 348 bp), in Spanish Churra sheep. A total of 22 synonymous single nucleotide polymorphisms (SNPs) were identified in the analysed sequence, which were genotyped in a set of eight sheep breeds with different productive aptitudes (dairy, meat and double aptitudes). Two of the SNPs identified, SNP03 (c.1450T>C) and SNP15 (c.5134T>C), which appeared to be breed-specific variations, were situated in the gene sequence coding for the biotin-carboxylase (BC) and acetyl-CoA carboxyltransferase (ACCT) domains of the protein, respectively. Particularly interesting is SNP12 (c.4579G>A), which displayed higher frequencies in the dairy-specialised breeds relative to the meat-producing breeds. Moreover, in the dairy breeds studied, the frequency of this SNP showed a positive correlation with the degree of dairy specialisation. A previously described alternative splicing site (Ser-1200) affecting an important regulatory region of the enzyme was observed in one of the Churra animals. Despite the high genetic variability observed in this gene, none of the identified SNPs caused an amino acid change. However, these polymorphisms could be in linkage disequilibrium with other mutations showing a functional effect on the ACACA enzyme. Hence, the characterisations of the allelic variants reported herein lay the groundwork for evaluation of the potential use of these SNPs as genetic markers of fat content and fatty acid composition in sheep dairy products.

Characteristics of traditional Croatian ewe's cheese from the island of Krk

Krk cheese is a hard, full‐fat cheese made from raw sheep's milk, characterized by a delicate, full and strong flavour. The aim of this study was to determine farm influence on the chemical composition of sheep's milk for Krk cheese production, and the chemical characteristics of Krk cheese during ripening. Gross composition of the milk used complies with the average sheep's milk composition from the Croatian Adriatic region. During ripening, fat, protein, salt content and lactic acid concentration increased (P < 0.01), as well as the water‐soluble nitrogen fraction and the 12%‐trichloroacetic‐acid‐soluble nitrogen fraction (P < 0.05). Degradation of β‐casein could be an indicator of the ripening quality of Krk cheese.

Effects of nutrition on the contents of fat, protein, somatic cells, aromatic compounds, and undesirable substances in sheep milk

This review discusses current knowledge of the main nutritional factors that influence composition of sheep milk and, consequently, its processing into cheese, with special focus on milk fat and protein concentration and characteristics, content of bioactive compounds, somatic cell content, content of aromatic compounds able to improve its organoleptic characteristics and content of toxic substances. Sheep milk composition is strongly influenced by ewe nutrition, especially in highly productive animals. Milk fat concentration is markedly affected by the ewe's net energy (NE) balance, dietary NDF content and dietary supplementation with ruminally protected/inert or unprotected marine and vegetable oils. Milk fat composition can be modified to contain higher levels of human healthy fatty acids (FA), such as conjugated linoleic acid and omega-3 FA. Milk protein content, and its characteristics, are more difficult to change than milk fat, although dietary energy seems to have a major role, while diet protein and amino acid supplementation only marginally affect milk protein level and its characteristics. Nutritional stress, and some vitamins, affect the somatic cell content of milk and this impacts cheese yield and quality. Feeds in the diet can markedly influence milk aroma and, consequently, play a role in determining cheese flavor, especially when ewes are pastured. Possible sources and causes of contamination of sheep milk by heavy metals or dioxins, and mycotoxins, through the diet are also addressed. Overall, quality and safety of sheep milk can be modified and improved by the nutrition characteristics of the diet.

Managing Mediterranean pastures in order to enhance the level of beneficial fatty acids in sheep milk

This paper updates our knowledge on the effects of the botanical composition and management of Mediterranean pastures on the fatty acid composition of sheep milk and cheese. It focuses on the effects of the forage species and its phenological phase on: (i) the fatty acid profile of the forage, and (ii) the milk fatty acid composition. Here we refer specifically to putatively beneficial fatty acids (mono- and poly-unsaturated fatty acids (PUFA)), including conjugated linoleic acid (CLA, C18:2 c-9, t-11) and vaccenic acid (C18:1 t-11). A database was set up compiled from the results of various studies carried out by our research group and this was statistically analysed. Both the forage species ( P < 0.05) and its phenological phase ( P < 0.08) affected the content of linoleic acid, a precursor of CLA in the forage. The PUFA level in milk was higher in ewes grazing pure legumes and grass–legume mixtures than in those grazing pure grass pastures. When the pasture mixture also contained a daisy plant ( Chrysanthemum coronarium), the CLA and vaccenic acid levels were even higher. Linoleic (C18:2; c-9, c-12) linolenic (C18:3; c-9, c-12, c-15) CLA (C18:2; c-9, t-11) and vaccenic acid (C18:1; t-11) levels in milk decreased from the vegetative (early-mid lactation) to the reproductive phase (late lactation). The Δ 9 desaturase activity (estimate by C14:1/C14:0 ratio), which is involved in the conversion of vaccenic acid to CLA in the mammary gland, supports the hypothesis that the lower the substrate supply the higher the endogenous CLA synthesis. Finally, no marked differences were found in the fatty acid composition of milk and cheese from dairy sheep. Guidelines for managing the nutrition of grazing sheep to increase the unsaturated fatty acid content in milk are discussed.

The influence of somatic cell count on sheep milk composition and cheese-making properties

RiassuntoInfluenza del contenuto in cellule somatiche sulla composizione del latte ovino e sulle caratteristiche del formaggio. Allo scopo di valutare gli effetti del contenuto in cellule somatiche (CCS) sulla qualità del latte e del formaggio Pecorino, è stata condotta una prova in un allevamento di ovini Valle del Belice. Da febbraio a luglio, ogni 15 d, il latte di tutte le pecore in lattazione è stato analizzato per il CCS in modo da ottenere due tipi di latte, a basso (<1.000.000) ed alto (da 1.000.000 a 3.000.000) tenore in cellule. Sul latte di massa sono state effettuate le analisi chimiche (grasso, frazioni azotate, urea, lattosio, calcio, fosforo), citologiche (carica batterica, CCS), fisiche (pH, acidità titolabile, punto crioscopico) e tecnologiche (r, a30 e K20). Il latte di massa è stato caseificato separatamente per tipo di latte. I risultati hanno evidenziato una marcata influenza del CCS sulla qualità del latte, in accordo con quanto riportato in letteratura; nessuna influenza è stata osservata sui formaggi freschi e stagionati.

Amino acid composition of sheep milk from the tsigai breed

The amino acid composition of total protein in sheep milk obtained from ewes of Tsigai breed during the grazing season (April - July) in 2002 was determined. The variation in the amounts of total protein and the dry fat-free residue in the milk produced during the grazing season exercise impact on its amino acid composition. Generally, sheep milk had higher percentage of monoaminocarbonic acids ranging from 13.1% to 13.4%. The total amount of essential amino acids increases proportionally to the changes in the milk composition during the grazing season.

The effects of dietary urea and ammonium sulphate on the yield and composition of sheep milk

SummaryAn experiment lasting 4 years has been carried out with 4 groups (3 test and a control) of 10 sheep. Non-protein nitrogen (NPN) (as urea, ammonium sulphate or a mixture of the two) replaced 25% of the dietary nitrogen in the first 2 years and 50% in the second 2 years. The yields of milk, protein and fat were generally depressed in the test groups but not all of the differences reached significance. In the group receiving ammonium sulphate, the milk fat percentage was higher than in the control group in all years and the protein percentage was higher in the last 2 years. Contrary to results elsewhere, the yield of lactose was depressed in all test groups. In the urea group, the content of minerals and of calcium in the milk was significantly less than in the control groups. The total amount of NPN and its components (ammonia, urea and creatine) in milk were not affected by the substitution of NPN in the rations.