Dairy Sheep Research Articles

Influence of the storage temperature of raw sheep milk on the spoilage potential of Pseudomonas spp.

Due to their quality, high yield and nutritional value, sheep dairy products have been gaining market space and attracting new producers. Pseudomonas spp. is the most common psychrotrophic genus present in bovine refrigerated raw milk and is characterized by intense lipoproteolytic activity. Metalloprotease aprX is one of the enzymes produced by Pseudomonas spp. which has great industrial importance, since it has specific activity in the deterioration of casein, resulting in significant changes in physicochemical properties and sensorial characteristics of raw milk and dairy products. The aim of this study was to observe the occurrence of Pseudomonas spp. in raw sheep milk and evaluate the influence of storage temperature on the spoilage potential of the strains. Raw sheep milk samples were stored at 4 °C or 9 °C (72 h) and plated in Pseudomonas Agar Base supplemented with CFC (25 ºC / 48 h). The isolates characteristic of Pseudomonas had their genus, species (P. putida, P. fluorescens and P. aeruginosa), and presence of gene aprX confirmed by Polymerase Chain Reaction (PCR). The lipoproteolytic capacity and the spoilage potential of the isolates were evaluated in Milk Agar (10%) and Tributyrin Agar Base (1%) (21 °C / 72 h). Initial (2 h) populations of Pseudomonas spp. ranged from 1.0 to 4.2 log CFU/mL; after 72 h, the values observed in milk samples stored at 9 °C (3.0–7.0 log CFU/mL) were higher than those obtained in samples at 4 °C (1.6–6.0 log CFU/mL). A total of 255 strains of Pseudomonas spp. were isolated: 30.2% (77) from milk stored at 4 °C and 69.8% (178) from milk at 9 °C. At both temperatures, P. fluorescens was predominant, followed by P. putida. P. aeruginosa strains, isolated only from samples stored at 9 °C, showed high lipoproteolytic capacity and were characterized by higher proteolytic potential than lipolytic. P. fluorescens was the only species to present high proteolytic (halos > 2 cm) potential. Considering a single storage temperature (4 °C and 9 °C), only P. fluorescens showed higher proteolytic potential than lipolytic. The aprX gene was predominant in P. fluorescens and P. putida isolates (4 °C and 9 °C); strains obtained from milk stored at 4 °C showed higher proteolytic potential than those isolated from milk at 9 °C. All strains of P. fluorescens and only 46.42% of P. putida presented proteolytic capacity at 9 °C. The aprX gene was observed in all P. aeruginosa strains, but only 95.65% of them showed proteolytic capacity. The lipolytic potentials of P. fluorescens and P. putida were not influenced by milk storage temperature. P. fluorescens was the only species to present high lipolytic potential. P. putida isolated from milk at 9 °C was the only species to present higher lipolytic potential than proteolytic. According to the microbiota and the storage temperature, there may be a predominance of proteolytic or lipolytic enzymes in milk and consequently, defects in sheep dairy products. It should also be considered that most of the isolates of Pseudomonas spp. presented lipoproteolytic capacity, which emphasizes the importance of low initial populations of this microorganism in raw sheep-chilled milk, mainly when used in the production of dairy products.

Outbreak of Acute Clinical Mastitis in Primigravidae Ewes in the Immediately Pre-Partum Period

An outbreak of acute mastitis was investigated in a dairy sheep farm in Central Greece with a prevalence of 8.2%. Two animals were examined with symptoms of hyperacute inflammation in one of the two mammary glands. Affected glands presented swollen to grossly enlarged, warm and painful. In both animals, haematological examination revealed mild anaemia, increased leucocyte counts with mature neutropaenia and left shift, and marked thrombocytosis. Bacteriological examinations of mammary gland secretion yielded heavy growth of Streptococcus dysgalactiae and Escherichia coli from each of the two animals, respectively. Serological examination revealed a high percentage of positive samples for small ruminant lentivirus infection in both animals. The somatic cell count in the bulk-tank milk was 0.65 × 106 cells/mL. The housing conditions were inadequate with high levels of ammonia, intense stocking and muddy bedding. This pathological condition in nulliparous ewes was attributed to the extensive oedema of mammary gland and teat, the relaxation of immunity during the peri-parturient period and the heavily contaminated environment. These findings are in general agreement with corresponding incidents in heifers. Following our instructions for improving housing conditions, no other similar incidents were recorded.

Effect of crude glycerin supplementation via drinking water on feed intake, water intake and productive performance of dairy ewes.

This study was performed to determine the effects of crude glycerin (CG) supplementation in drinking water on DM and nutrient intake, milk production, milk composition, and serum glucose. Twenty multiparous Lacaune × East Friesian ewes were randomly distributed into four dietary treatments throughout the lactation cycle. Treatments consisted of doses of CG supplementation via drinking water as follows: (1) no CG supplementation, (2) 15.0 g CG/kg DM, (3) 30.0 g CG/kg DM, and (4) 45.0 g CG/kg DM. DM and nutrient intake were reduced linearly with CG supplementation. CG linearly reduced water intake when expressed as kg d-1. However, no effect of CG was observed when it was expressed as a percentage of body weight or metabolic body weight. The water to DM intake ratio was increased linearly with CG supplementation. No effect of CG doses on serum glucose was observed. The production of standardized milk decreased linearly with the experimental doses of CG. Protein, fat, and lactose yield were linearly reduced with the experimental doses of CG. Milk urea concentration was quadratically increased with CG doses. Feed conversion was quadratically increased by treatments during the pre-weaning period (P < 0.05), in which the worst values were observed when the ewes were supplemented with 15 and 30 g CG/kg DM. The N-efficiency was linearly increased with CG supplementation in drinking water. Our results suggest that dairy sheep can be supplemented with CG up to 15 g/kg DM in drinking water. Greater doses are not beneficial for feed intake, milk production, and the yield of milk components.

FarmDain, a Decision Support System for Dairy Sheep and Goat Production.

Managing a milk zone in the dairy industry is demanding. Data necessary for efficient management are difficult to acquire because they usually must be collected in organized and standardized ways. On the other hand, software practices constantly provide new tools that can go beyond simple record-keeping practices and add value to the data. In this work, FarmDain is a novel web-based application for sheep and goat management. It aims to improve milk production and processing by digitizing the value chain in data acquisition, processing and visualization between dairy production businesses and their milk suppliers. FarmDain uses state-of-the-art software technologies to model the data collection process and provides a straightforward user interface to facilitate data processing and visualization. Using the app in a case study carried out for 12 months in a dairy sheep farm resulted in lower feeding cost per milked ewe by 5.5% when ewes were allocated into high and low milk production groups compared to the scenario of remaining in one single group. Furthermore, based on reports provided by the app, culling and genetic selection decisions were made to improve the overall farm performance. Similar practices were applied in all farms optimizing their productivity, which led to increased profitability for farms and the Dairy Factory.

Plasma and milk metabolomics in lactating sheep divergent for feed efficiency

Enhancing the ability of animals to convert feed into meat or milk by optimizing feed efficiency (FE) has become a priority in livestock research. Although untargeted metabolomics is increasingly used in this field and may improve our understanding of FE, no information in this regard is available in dairy ewes. This study was conducted to (1) discriminate sheep divergent for FE and (2) provide insights into the physiological mechanisms contributing to FE through high-throughput metabolomics. The ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q/TOF-MS) technique was applied to easily accessible animal fluids (plasma and milk) to assess whether their metabolome differs between high- and low-feed efficient lactating ewes (H-FE and L-FE groups, respectively; 8 animals/group). Blood and milk samples were collected on the last day of the 3-wk period used for FE estimation. A total of 793 features were detected in plasma and 334 in milk, with 100 and 38 of them, respectively, showing differences between H-FE and L-FE. The partial least-squares discriminant analysis separated both groups of animals regardless of the type of sample. Plasma allowed the detection of a greater number of differential features; however, results also supported the usefulness of milk, more easily accessible, to discriminate dairy sheep divergent for FE. Regarding pathway analysis, nitrogen metabolism (either anabolism or catabolism) seemed to play a central role in FE, with plasma and milk consistently indicating a great impact of AA metabolism. A potential influence of pathways related to energy/lipid metabolism on FE was also observed. The variable importance in the projection plot revealed 15 differential features in each matrix that contributed the most for the separation in H-FE and L-FE, such as l-proline and phosphatidylcholine 20:4e in plasma or l-pipecolic acid and phosphatidylethanolamine (18:2) in milk. Overall, untargeted metabolomics provided valuable information into metabolic pathways that may underlie FE in dairy ewes, with a special relevance of AA metabolism in determining this complex phenotype in the ovine. Further research is warranted to validate these findings.

Alternative hormone-free reproduction management of a dairy sheep flock disrupts the farm's annual feeding system calendar and its associated strategies

Hormone-free (HF) reproduction in dairy sheep is a way to meet current societal demands, but it requires being prepared for collateral impacts on related system components. The efficiency of HF practices (e.g., using the male effect for estrus induction and synchronization) is uncertain compared with hormonal treatment (HT). For example, these practices can lead to higher variability in the flock physiological stage patterns throughout the year, which has direct consequences for feeding regimens. The objective of this work was to simulate the impacts of HF reproduction management, including artificial insemination (AI), on the temporal distribution of productive performance and nutritional requirements of a conventional dairy sheep flock. Using the REPROsheep2.0 model, 6 scenarios were compared over one typical production season for the same flock (n = 597 Lacaune ewes) intensively reared in the Roquefort region of France. These scenarios depicted reproduction with HT and AI in mid-May (Early); HT and AI in July (Summer Late); HT and AI in November (Autumn Late); and their HF versions (HF-Early; HF-Summer Late, and HF-Autumn Late, respectively). In all HF scenarios, a reduction in the number of ewes lambing and consequently in the annual milk production of the farm was observed (-1 to -7%). This affected annual performance with a subsequent decrease of total annual nutritional requirements (-2 to -6%). The HF scenarios resulted in a staggering of lambing events with a 7- to 14-d shift in the appearance of milk production peaks and related nutritional requirements compared with the HT scenarios. Transitioning from conventional to HF reproduction management, while preserving AI, would increase farm workload, lengthen milking period operations, and necessitate a readjustment of feeding management strategies with regard to available feed resources. Depending on the production season, the observed delay in the distribution of nutritional requirements could be either an attractive or an unfavorable outcome for farmers. The delay may be concordant, for example, with the recently observed impacts of climate change on seasonal forage availability in Mediterranean regions (less spring herbage production and warmer temperatures) that are affecting farmers' decision-making about the most efficient use of forage and feed resources.

Identification of Genetic Polymorphisms of PI, PIII, and Exon 53 in the Acetyl-CoA Carboxylase-α (ACACα) Gene and Their Association with Milk Composition Traits of Najdi Sheep.

Recently, increasing attention has been paid to sheep milk products, which are high in saturated fatty acids (SFA), and the extent of their impact on human health. This study aimed to identify SNPs for PI, PIII, and Exon 53 in the ACACα gene and their association with the MC and FA profiles in Najdi sheep milk. A total of 76 multiparous Najdi ewes were used, and they were maintained using the same feeding system. Milk and blood samples were collected during the first lactation. A genetic polymorphism analysis identified 20 SNPs: 4 SNPs on PI, 6 SNPs on PIII, and 10 SNPs on Exon 53. In PI, the SNP g.4412G > A was associated (p < 0.05) with palmitic acid (C16:0), palmitoleic acid (16:1 n-7) and linoleic acid (LA), while SNP g.4485C > G was associated with CLA and vaccenic acid (VA) (p < 0.05). Furthermore, in PIII, two SNPs (g.1168A > G and g.1331G > T) were associated with milk protein (p < 0.05), while the SNP g.6860G > C in Exon 53 was associated with milk fat (p < 0.05). SNPs in the Najdi breed have been shown to be strongly related to milk fat and EFA contents. This could support a genetic selection program and the control of milk traits in the Najdi breed of high-quality dairy sheep.

Understanding the phenotypic and genetic background of the lactose content in Sarda dairy sheep

Lactose, the principal carbohydrate found in milk, plays an important role in the physiological processes of milk production because it is related to milk volume, and it is responsible for the osmotic equilibrium between blood and milk in the mammary gland. In this study, factors affecting lactose content (LC) in sheep milk are investigated. For this purpose, 2,358 test-day records were sampled from 509 ewes (3-7 records per animal). The LC and other main milk traits were analyzed using a mixed linear model that included days in milk (DIM) class, parity, lambing month, and type of lambing as fixed effects and animal, permanent environment, and flock test day as random effects. The pedigree-based approach was used to estimate the heritability and repeatability of LC. Moreover, the genomic background of LC was investigated through a GWAS. The LC was affected by all tested factors (i.e., DIM class, parity, lambing month, and type of lambing). Low heritability (0.10 ± 0.05) and moderate repeatability (0.42 ± 0.02) were estimated for LC. High negative genetic correlations were estimated between LC and NaCl (-0.99 ± 0.01) and between LC and somatic cell count (-0.94 ± 0.05). Only 2 markers passed the chromosome-wide Bonferroni threshold. Results of the present study, although obtained on a relatively small sample, suggest the possibility to include LC in the breeding programs, particularly because of its strong relationship with NaCl and somatic cell count.

Feed efficiency in dairy sheep: An insight from the milk transcriptome.

As higher feed efficiency in dairy ruminants means a higher capability to transform feed nutrients into milk and milk components, differences in feed efficiency are expected to be partly linked to changes in the physiology of the mammary glands. Therefore, this study aimed to determine the biological functions and key regulatory genes associated with feed efficiency in dairy sheep using the milk somatic cell transcriptome. RNA-Seq data from high (H-FE, n = 8) and low (L-FE, n = 8) feed efficiency ewes were compared through differential expression analysis (DEA) and sparse Partial Least Square-Discriminant analysis (sPLS-DA). In the DEA, 79 genes were identified as differentially expressed between both conditions, while the sPLS-DA identified 261 predictive genes [variable importance in projection (VIP) > 2] that discriminated H-FE and L-FE sheep. The DEA between sheep with divergent feed efficiency allowed the identification of genes associated with the immune system and stress in L-FE animals. In addition, the sPLS-DA approach revealed the importance of genes involved in cell division (e.g., KIF4A and PRC1) and cellular lipid metabolic process (e.g., LPL, SCD, GPAM, and ACOX3) for the H-FE sheep in the lactating mammary gland transcriptome. A set of discriminant genes, commonly identified by the two statistical approaches, was also detected, including some involved in cell proliferation (e.g., SESN2, KIF20A, or TOP2A) or encoding heat-shock proteins (HSPB1). These results provide novel insights into the biological basis of feed efficiency in dairy sheep, highlighting the informative potential of the mammary gland transcriptome as a target tissue and revealing the usefulness of combining univariate and multivariate analysis approaches to elucidate the molecular mechanisms controlling complex traits.

The potential of improved animal welfare as an environmental impact mitigation strategy in dairy sheep farming

The potential of improved animal welfare as an environmental impact mitigation strategy in dairy sheep farming

Feed restriction around parturition does not affect colostrum immunoglobulin G concentration in dairy fat-tailed sheep but does affect performance and blood metabolites in newborn lambs

This study aimed to investigate the effect of prepartum and postpartum feed restriction of fat-tailed dairy sheep on colostrum IgG concentration, and performance and blood metabolites of newborn fat-tailed lambs. Twenty fat-tailed dairy sheep were randomly allocated into control (Ctrl; n = 10) and feed restriction (FR; n = 10) groups. The Ctrl group received a diet that met 100% of energy requirements, both prepartum (from wk -5 to parturition) and postpartum (from parturition to wk 5). The FR group received a diet equivalent to 100, 50, 65, 80, and 100% of the energy requirements in wk -5, -4, -3, -2, and -1 relative to parturition, respectively. After parturition, the FR group received a diet equivalent to the 100, 50, 65, 80, and 100% of the energy requirements in wk 1, 2, 3, 4, and 5, respectively. At birth, lambs were assigned to their dam's experimental group. Both the Ctrl lambs (n = 10) and the FR lambs (n = 10) were allowed to suck colostrum and milk from the dams. Colostrum samples (50 mL) were collected at parturition (0 h) and then at 1, 12, 24, 36, 48, and 72 h postpartum. Blood samples were collected from all lambs before suckling colostrum (0 h) and then at 1, 12, 24, 36, 48, and 72 h after birth and weekly until the end of the experimental period (i.e., wk 5 relative to birth). The data were evaluated using the MIXED procedure of SAS (SAS Institute Inc.). The model included feed restriction, time, and the interaction feed restriction × time as fixed effects. The individual lamb was set as a repeated subject. Variables measured in colostrum and plasma were considered dependent variables, and significance was set at P < 0.05. Prepartum and postpartum feed restriction in fat-tailed dairy sheep did not affect colostrum IgG concentration. Consequently, no differences in blood IgG concentrations were observed in the lambs. In addition, the prepartum and postpartum feed restriction experienced by fat-tailed dairy sheep caused decreased body weight and milk intake in lambs from the FR group compared with the Ctrl group. Feed restriction also promoted increased concentration of blood metabolites such as triglycerides and urea in FR lambs compared with control lambs. In conclusion, prepartum and postpartum feed restriction in fat-tailed dairy sheep did not affect either colostrum IgG concentration or blood IgG concentration of the lambs. However, prepartum and postpartum feed restriction decreased lamb milk intake and, therefore, lamb body weight gain during the first 5 wk after birth.

O-045 Correlation of fecal egg count with clinical parameters in dairy sheep

O-045 Correlation of fecal egg count with clinical parameters in dairy sheep

P-029 Ultrasound diagnosis of pregnancy disorders in dairy sheep, incidence and correlations

P-029 Ultrasound diagnosis of pregnancy disorders in dairy sheep, incidence and correlations

P-080 Absence of adverse effects after a double intravaginal administration of Lactobacillus spp. in dairy sheep: A preliminary study

P-080 Absence of adverse effects after a double intravaginal administration of Lactobacillus spp. in dairy sheep: A preliminary study

O-101 Field evidence for association between increased gastrointestinal nematode burden and subclinical mastitis in dairy sheep

O-101 Field evidence for association between increased gastrointestinal nematode burden and subclinical mastitis in dairy sheep

O-141 Lack of efficacy of topical administration of eprinomectin against gastrointestinal nematode in a French dairy sheep farm

O-141 Lack of efficacy of topical administration of eprinomectin against gastrointestinal nematode in a French dairy sheep farm

P-091 A comparative study of milk quantity, quality traits between a maedi-visna infected, a maedi-visna free dairy sheep farm

P-091 A comparative study of milk quantity, quality traits between a maedi-visna infected, a maedi-visna free dairy sheep farm

O-195 Strategic analysis of the dairy sheep production systems in Brazil – An approach by SWOT methodology

O-195 Strategic analysis of the dairy sheep production systems in Brazil – An approach by SWOT methodology

O-193 Attitude of cheese consumers towards the sustainability of dairy sheep production systems

O-193 Attitude of cheese consumers towards the sustainability of dairy sheep production systems

O-143 Resistance to eprinomectin in gastro-intestinal nematodes of dairy sheep: What part do breed and summer pastures play?

O-143 Resistance to eprinomectin in gastro-intestinal nematodes of dairy sheep: What part do breed and summer pastures play?