Udder Halves Research Articles

Connection of somatic cell count and milk yield as well as composition in dairy ewes

Abstract. The aim of this study was to determine the effect of somatic cell count (SCC) on milk yield and composition using a threshold value of 250 ∙103 cells/ml in dairy ewes of line 05. A total of 1 512 milk samples from udder halves were collected throughout milking periods at monthly intervals. In the present study milk composition (from halves of the udder) and daily milk yield (from udders) was examined in terms of SCC in ewe milk in three groups: from both halves of the udder below 250 ∙103 cells/ml, from one halves of the udder below 250 ∙103 cells/ml and from second half udder above 250 ∙103 cells/ml and from both halves of the udder above 250 ∙103 cells/ml. Milk yield from udders, somatic cell count in milk samples from udder halves and milk composition depended on the level of SCC recorded for halves of the udder. Somatic cell counts in milk from one or both halves of udders exceeding 250 ∙103 cells/ ml resulted in a statistically significant (P<0.01) decrease in daily milk production of ewes, by approx. 15.89 and 30.22 %, respectively. The analysis of variance showed also a significant effect of parity and stage of lactation of ewes on somatic cell count (log SCC) and milk composition from udder halves below 250 ∙103 cells/ml.

Somatic cell count, lactoferrin and NAGase activity in milk of infected and non-infected udder halves of dairy goats

Based on a repeated sampling the influence of an intramammary infection on the somatic cell count (SCC), the content of lactoferrin (Lf) and the activity of N-acetyl-β- d-glucosaminidase (NAGase) in goats’ milk was investigated. 58 dairy goats (German Improved Fawn) were sampled weekly over 3 consecutive weeks and the udder halves were classified according to the results of the bacteriological analysis of the foremilk samples and the results of their parallel half into three groups: uninfected halves with an uninfected parallel half (NoInf/NoInf), uninfected halves with an infected parallel half (NoInf/Inf) and infected halves with an uninfected parallel half (Inf/NoInf). None of the goats had two infected halves, thus, this group was omitted. 15 out of the 58 goats were infected on one udder half. The bacteria detected were Staphylococcus aureus ( n = 4), coagulase-negative staphylococci ( n = 7), corynebacteria ( n = 3) and esculin-positive streptococci ( n = 1). Log 10 SCC, log 10 Lf and log 10 NAGase were strongly correlated to each other and changed over the sampling period but not uniformly, revealing a significant effect of the sampling day on the variables ( F 6,98 = 29.13, p < .001). This could not be explained by an underlying effect due to the stage of lactation or the estrus season the animals were in, and therefore needs further investigation. The infection status had a significant effect on log 10 SCC ( F 2,103 = 20.22, p < .001), log 10 Lf ( F 2,103 = 11.18, p < .001) and log 10 NAGase ( F 2,103 = 12.06, p < .001). Inf/NoInf differed significantly from NoInf/NoInf as well as NoInf/Inf for log 10 SCC ( p < .01) and log 10 Lf ( p < .001) whereas the NoInf/NoInf did not differ from NoInf/Inf indicating that the infected halves did not influence their uninfected parallel half. For log 10 NAGase this was different: infected halves differed significantly from NoInf/NoInf ( p < .01) but not from NoInf/Inf which might be caused by a dependency of the udder halves. Results support the approach to monitor mastitis in goats by means of Lf or NAGase instead of SCC. Further studies should explore the effect of other independent variables, such as estrus, on these indicators and aim for thresholds indicating an intramammary infection.

The effects of milk removal or four-times-daily milking on mammary expression of genes involved in the insulin-like growth factor-I axis

Frequent milking of dairy cows during early lactation elicits both an immediate increase in milk yield and a partial carryover effect that persists to the end of lactation. We hypothesized that the immediate response would be associated with a local increase in insulin-like growth factor (IGF)-I signaling and a consequent increase in mammary growth. Four multiparous cows were assigned at parturition to unilateral frequent milking [UFM; milking of the left udder half twice daily (2×; 0230 and 1430h); milking of the right udder half 4 times daily (4×; 0230, 0530, 1430, and 1730h)]. Mammary biopsies were obtained from both udder halves at 5 d in milk at 0530h (immediately after 4× glands were milked). Incorporation of [3H]-thymidine into DNA and mammary cell apoptosis were not affected by UFM. Because biopsies were obtained when udder halves were at different postmilking intervals, our results reflected both the acute, transient mammary response to milking and the sustained mammary response to frequent milking treatment. We further hypothesized that the acute, transient response involves mechanisms distinct from those regulating the sustained response to frequent milking. To test that hypothesis, mammary biopsies were obtained from UFM cows (n=5) at 0500h, when time postmilking was the same for both udder halves. Mammary cell apoptosis was not affected by UFM. Expression of genes involved in the IGF-I axis was analyzed to identify acute responses associated with milking, per se, versus sustained responses to frequent milking treatment. Removal of milk from 4× glands was associated with an acute increase in expression of IGF binding protein-1, -3, and -4 mRNA in 2× glands, whereas IGF-I expression was increased by frequent milking treatment. These effects, however, were significant only for expression of IGF binding protein-3. Expression of IGF-I receptor did not differ because of milking frequency but was higher in both udder halves immediately postmilking, indicating a systemic effect. We conclude that several genes of the IGF-I axis respond to milking, per se, or frequent milking treatment, via at least 3 distinct patterns. Increased milking frequency does not alter mammary cell proliferation or apoptosis at 5 d in milk; however, it may increase the bioavailability of IGF-I in the mammary gland. Moreover, the increase in local expression of IGF-I in 4× udder halves indicates a role for this gene in the immediate milk yield response to frequent milking during early lactation.

Hygienic and health characteristics of donkey milk during a follow-up study

For its characteristics, donkey milk has been proposed as an alternative to goat or artificial milk to feed allergic infants. Therefore, it is important to increase our knowledge on health and immunological characteristics of donkey milk. Ten donkeys, bred as companion animals, were enrolled in this study and sampled once a month, for eight months. Milk (10 ml) was collected from each half udder for somatic cell count (SCC), bacteriological analysis and total bacteria count (TBC). The major pathogens were tested for antimicrobial susceptibility, and Staphylococcus aureus isolates were further genotyped by nanoarray analysis. Whey lysozyme and NAGase (NAG) activities were also assessed. Overall, 101 half-udder milk samples were taken. They showed very low values of TBC (<250 cfu/ml) and SCC (<50 000 cells/ml) and a minor prevalence of pathogens: Staph. aureus was isolated only from 5 milk samples (3 animals), Streptococcus equi from 2 samples and Str. equisimilis from a single sample. All the isolates were sensitive to all antibiotic classes used in veterinary medicine. None of the Staph. aureus isolates were shown to harbour genes coding for any enterotoxin, toxic-shock syndrome toxin or antibiotic resistance. Lysozyme levels were always very high (4000-5000 U/ml), while NAG values were mostly low (<50 U/ml), out of the last part of lactation. The results of this study confirmed the low prevalence of intramammary infections in donkey and the absence of food-borne pathogens, suggesting that donkey milk could be a safe food, if the mammary gland is healthy and the animals are milked in proper hygienic conditions.

Occurrence of mastitis and associated risk factors in lactating goats under pastoral management in Borana, Southern Ethiopia

Mastitis prevalence and related risk factors were studied in 1,072 udder halves of 536 lactating goats from October, 2008 to February, 2009. Clinical and subclinical mastitis were prevalent in 4.3% (95% CI = 2.8, 6.5) and 11.2% (95% CI = 8.7, 14.3) of the studied animals, respectively, resulting in an overall prevalence of 15.5% (95% CI = 12.6, 18.9). Univariate analysis of the potential risk factors has depicted that mastitis was more prevalent in does with previous mastitis history, increased parity, poor body conditions, increased milk production, late lactation stage, long teat, and housed goats. Furthermore, prevalence was significantly higher (p < 0.05) during the wet period of October to November than the dry periods of January to February. No significant variations (p > 0.05) were observed in mastitis prevalence with udder tick infestation, mixing goat with sheep and flock size. With multivariable analysis, lactation stage, teat length, body condition, and season (wet months) have showed significant association with mastitis prevalence, and these factors maintained significant in the stepwise elimination of multivariable logistic regression model. As a result, does in late stage of lactation (OR = 4.3, 1.8, 10.4), poor body condition (OR = 5.0, 1.7, 10.0), long teats (OR = 2.2, 95% CI = 1.1, 4.2) and does examined in wet period were at higher risk of udder infections than early lactation, good body condition, short teat, and examined in dry period, respectively. The study showed occurrence of mastitis and associated risk factors in studied goats, which suggests the need for control intervention. Further investigations into pathogens involved in goat mastitis will optimize our knowledge of causative agents and control interventions.

Milk electrical conductivity and mastitis status in dairy goats: Results from a pilot study

Mastitis in small ruminants has a major effect in reducing both yield and quality of milk leading to strong economic losses. In addition, mastitis is one the most frequently cited reason for culling. In dairy cows electrical conductivity (EC) of milk has been introduced as an indicator trait for mastitis. When the measurement of electrical conductivity (EC) of milk is based on time-series analysis of historical data, comparing values from different quarters within milking, satisfactory results in mastitis detection can be achieved. On the contrary, mastitis detection models based on EC measurement of milk within milking are not available in literature for dairy goats. Aim of the study was to evaluate the usefulness of milk EC, measured within milking from halves of each udder, to predict mastitis status in dairy goats at farm level. For this purpose, a group of 8 Saanen goats was involved in a 225-day study. Two foremilk samples were daily collected during morning milking from halves of each udder for a total of 4 samples per animal/day. Results of bacteriological analyses were used to distinguish between healthy (absence of mastitis agents) and infected (presence of contagious or environmental mastitis agents) udder halves. EC was measured in milk from halves of each udder during every morning milking at 1-s intervals using four experimental milking units equipped with conductimetric sensors. The average of the 20 highest EC values ( X 20 ) and the variation of the 20 highest EC values ( σ 20 2 ) within milking were calculated for each udder halves. In addition 4 EC traits based on X 20 and σ 20 2 were computed: the highest half udder X 20 value within goat and milking (Max_ X 20) , the highest half udder σ 20 2 value within goat and milking ( Max _ σ 20 2 ), the inter-udder halves ratio between the udder halves X 20 values within goat and milking (IHR_ X 20 ), and the inter-udder halves ratio between udder halves σ 20 2 value within goat and milking ( IHR _ σ 20 2 ). Values for the traits were calculated for every milking throughout the whole lactation. Proc Mixed of SAS ® 9.1 (SAS Institute Inc., Cary, NC, USA, 2008) was performed to test for significant differences in EC traits between healthy and infected udder halves and between healthy (absence of infected udder halves) and infected (presence of at least one infected udder half) goats. Results highlighted that the average of the 20 highest electrical conductivity half udder values recorded within milking in early lactation and the highest half udder X 20 value within goat and milking in mid lactation could be potentially used in monitoring udder health of dairy goats.

The prevalence of the profile of clinical signs of mastitic goats in North-Western and Central parts of Nigeria

A total of one hundred and three (103) does had mastitis among the one thousand three hundred and twenty three (1323) goats estimated at villages in three states; Zamfara. Kebbi and Kaduna within two years. The prevalence of mastitis among the goats was 7.8%. The clinical manifestations of mastitis in goats and the factors which predisposed goats to mastitis were studied. The data obtained were subjected to analysis using SPSS. Of the total number of milk samples examined, 95 % were significantly of normal milk color (P&lt;0.05) while blood tinged and greenish milk were the least statistically significant manifestation (P&lt;0.05). Flock size, kidding season, halves of udder affected, kids per parturition, age of doe and parity significantly increased the occurrence of Caprine mastitis (P&lt;0.05). Key words: Mastitis, Goats, Kidding, Parturition.

Continuous lactation effects on mammary remodeling during late gestation and lactation in dairy goats

The present study aimed to 1) elucidate whether continuous milking during late gestation in dairy goats negatively affects mammary remodeling and hence milk production in the subsequent lactation, and 2) identify the regulatory factors responsible for changes in cell turnover and angiogenesis in the continuously lactating mammary gland. Nine multiparous dairy goats were used. One udder half was dried off approximately 9 wk prepartum (normal lactation; NL), and the other udder half of the same goat was milked continuously (continuous lactation; CL) until parturition or until the half-udder milk yields had dropped to below 50 g/d. Mammary biopsies were obtained from each udder half just before the NL gland was dried off (before dry period), within the first 2 wk after drying-off (early dry period, samples available only for NL glands), in the mid dry period, within the last 2 wk before parturition (late dry period), and at d 1 (the day of parturition), 3, 10, 60, and 180 of lactation. Mammary morphology was characterized in biopsies by quantitative histology, and cell turnover was determined by immunohistochemistry (terminal deoxynucleotidyl transferase dUTP nick end labeling and Ki-67). Transcription of genes encoding factors involved in mammary epithelial cell (MEC) turnover and vascular function was quantified by quantitative reverse transcription PCR. Results demonstrated that omitting the dry period was possible in goats but was not as easy as claimed before. Renewal of MEC was suppressed in CL glands, which resulted in a smaller MEC population in the subsequent lactation. At the time of parturition (and throughout lactation), the mammary glands subjected to CL had smaller alveoli, more fully differentiated MEC, and a substantially larger capillary fraction compared with NL glands. The continuously lactating gland thus resembled a normally lactating gland in an advanced stage of lactation. None of the studied genomic factors could account for these treatment differences. The described characteristics in CL glands compared with NL glands indicated a gland maintained in lactation for a longer period.

Differentially expressed genes associated with Staphylococcus aureus mastitis in dairy goats

To study gene expression within the mammary glands of dairy goats with mastitis, mRNA was collected from milk somatic cells (MSCs) of left udder halves challenged with Staphylococcus aureus and right udder halves infused with PBS, as control, at different time points (0, 12, 24 and 48 h post-infection). Transcriptional profiles were investigated using bovine cDNA microarrays; of the total 288 differentially expressed genes identified with ANOVA analysis (False Discovery Rate = 0.05, 1.5-fold change), 26, 36 and 16 genes were down-regulated at 12, 24 and 48 h post-infection, respectively, while 60, 141 and 9 genes were up-regulated at the same corresponding time points. The expression profiles clearly changed at 24 h post-infection with 177 genes significantly altered, corresponding to a 10-fold increase of S. aureus bacterial count in milk from infected udders. Differential expression of selected genes (CD2BP2, BCAP31, MHCII, FOSL2, MAPK13, ILT5 and JUNB) was also confirmed by real-time PCR at the different time points considered, showing high correlation with the microarray measurements and high reliability of the microarray analyses. The most readily inducible classes of genes in caprine MSCs infected with S. aureus were pro-inflammatory cytokines, chemokines and their receptors; IL-1α, lymphotoxin alpha, granulocyte chemotactic protein (CXCL6), and IL-2 receptor gamma were all up-regulated in infected udders versus healthy controls. This study identified a number of differentially expressed genes induced by S. aureus intramammary infection and demonstrates the intricacy of the patterns of gene expression that influence host response to a complex pathogen of significant relevance to both human and veterinary medicine.

The role of lactate dehydrogenase, alkaline phosphatase and aspartate aminotransferase in the diagnosis of subclinical intramammary infections in dairy sheep and goats

The objective was to investigate the changes occurring in the activities of the enzymes lactate dehydrogenase (LDH), alkaline phosphatase (ALP) and aspartate aminotransferase (AST) in sheep and goat milk as a result of subclinical intramammary infections (IMI) and to evaluate the use of these enzymes for the diagnosis of subclinical IMI in dairy sheep and goats. A total of 206 samples of sheep milk and 162 samples of goat milk, obtained from equal udder halves, were used in the study. For each species they were divided into two groups: a no-infection group and a subclinical infection group. Activities of LDH, ALP and AST were significantly higher in the subclinical infection group than in the no-infection group (P<0.05) in both sheep (LDH: 350.42+/-11.25 v. 120.91+/-4.41; ALP: 2773.43+/-105.18 v. 2189+/-94.24; AST: 29.57+/-0.74 v. 17.32+/-0.46) and goats (LDH: 354.07+/-13.33 v. 103.79+/-3.75; ALP: 311.13+/-25.74 v. 137.24+/-19.62; AST: 27.59+/-6.42 v. 15.87+/-0.45). The activity of LDH was identified as indicator for subclinical IMI in both sheep and goats. The optimum cut-off values for LDH activity, offering the highest diagnostic sensitivity (DSn) and diagnostic specificity (DSp), determined by receiver operating characteristic (ROC) analysis, were at 197 U/l, 185 U/l and 197 U/l for sheep, goats and both species, respectively. DSn for sheep, goats and both species at these cut-off values was 92.8%, 98.2% and 94.0%, whereas DSp was 95.4%, 96.3% and 96.3%, respectively. It was concluded that the determination of LDH activity in milk serum is a sensitive and reliable method for the detection of subclinical IMI in dairy sheep and goats.

Variations in Milk Yield and Composition Between Fore and Rear Udder-Halves in She-Camel (Camelus Dromedarius)

Total number of Sixteen she-camels were chosen from a large herd of camel belonging to the Lahween tribe in Eastern Sudan. The breed is known locally as Arabi-Lahwee. The fore and rear udder- halves measurements including, depth and height of the udder, distances, diameter and length of the teats. The results revealed that the depth of fore quarters was 20.9+0.75 cm and which was significantly (p<0.01) deeper than the rear quarters (13.1+0.75 cm), the results also indicated significant differences (p<0.05) between the height of fore and rear udder halves, (110.9+0.36 versus 110.2+0.36 cm, respectively). The distance between teats in the fore quarters (13.2+0.36 cm) which was significantly (p<0.01) longer than rear quarters (9.9+ 0.36 cm), the teats diameter of the rear quarters (2.5+0.1 cm) that was significantly (p<0.01) greater than the diameter of the fore quarters (2...1+ 0.1 cm). Teat length on the other hand showed non- significant difference between the udder halves. The data pertaining to milk yield and composition of the fore and rear udder quarters indicated that rear udder half produced 57.5% of the total milk yield, whereas the fore quarters yielded only 42.5% (p<0.01). The rear quarters produced milk, which was highly sig. (p<0.01) richer in protein% (3.38+0.19) and P% (1.077+0.022) and significantly (p<0.05) richer in moisture% (90.42+0.34), K% (1.25+0.032) and pH (6.38+0.043), also scored high but non-significant values in fat% (3.31+0.18) and Ca% (7.169+0.034). While, the fore udder quarters scored highly significant (p<0.01) value in lactose % (3.25+0.3), significant (p<0.05) value in total solids% (10.44+0.312) and high and non significant, values in Na% (0.64+0.012) and ash% (0.59+0.027). The amount of nutrients contained in milk from rear quarters provided higher amount of nutrients compared to milk of fore quarters.

Response to somatic cell count-based selection for mastitis resistance in a divergent selection experiment in sheep

A divergent selection experiment in sheep was implemented to study the consequences of log-transformed somatic cell score (SCS)-based selection on resistance to natural intramammary infections. Using dams and progeny-tested rams selected for extreme breeding values for SCS, we created 2 groups of ewes with a strong divergence in SCS of approximately 3 genetic standard deviations. A survey of 84 first-lactation ewes of both the High and Low SCS lines indicated favorable responses to SCS-based selection on resistance to both clinical and subclinical mastitis. All clinical cases (n=5) occurred in the High SCS line. Additionally, the frequency of chronic clinical mastitis, as detected by the presence of parenchymal abscesses, was much greater in the High SCS line (n=21) than in the Low SCS line (n=1). According to monthly milk bacteriological examinations of udder halves, the prevalence of infection was significantly greater (odds ratio = 3.1) in the High SCS line than in the Low SCS line, with predicted probabilities of 37 and 16%, respectively. The most frequently isolated bacteria responsible for mastitis were staphylococci: Staphylococcus auricularis (42.6% of positive samples), Staphylococcus simulans, Staphylococcus haemoliticus, Staphylococcus xylosus, Staphylococcus chromogenes, Staphylococcus lentus, Staphylococcus warneri, and Staphylococcus aureus. The incidence of positive bacteriology was greater in the High SCS line (39%) than in the Low SCS line (12%) at lambing, indicating that High SCS line ewes were especially susceptible to postpartum subclinical mastitis. Negativation of bacteriological results from one sampling time point to the next was markedly different between lines after weaning (e.g., 41 and 84% in the High and Low SCS lines, respectively). This result was consistent with differences in the duration of infection, which was much greater in the High SCS line compared with the Low SCS line. Finally, ewes from the High SCS line consistently had greater SCS in positive milk samples than did ewes from the Low SCS line (+2.04 SCS, on average), with an especially large difference between lines during the suckling period (+3.42 SCS). Altogether, the preliminary results suggest that the better resistance of Low SCS line ewes, compared with High SCS line ewes, was principally characterized by a better ability to limit infections during the peripartum period, to eliminate infections during lactation, and quantitatively to limit the inflammation process and its clinical consequences.

Prevalence and aetiology of subclinical mastitis in goats

The study was conducted in 2006 on 20 French alpine goat farms in Croatia. Milk samples were taken from each udder half, for the mastitis test and the bacteriological test, 2120 samples in total. Subclinical mastitis was diagnosed in 211 out of 1060 goats, or in 20% of the studied population. Mastitis of one udder half was diagnosed in 84% of the affected population, while mastitis of both udder halves was diagnosed in 16% of the affected goats. A positive mastitis test reaction was identified in 605 samples (28%), and the pathogenic bacterium was isolated from 244 of these samples (36%). From 22 samples (1.5%) which were negative to mastitis test, pathogenic bacteria, namely S. aureus (21 samples) and Streptococcus D (1 sample), were isolated. Staphylococcus aureus was isolated from 72% mastitis test positive samples, coagulase-negative staphylococci in 16%, other bacteria were isolated from a smaller number of samples: Streptococcus D (6%), Bacillus spp. (2%), and E. coli (2%). The results of the study lead to the conclusion that the subclinical mastitis in goats has a prevalence of 20% on average which increases with higher lactation number. Staphylococcus aureus is the primary causative agent of the inflammations.

Prevalence and etiology of subclinical mastitis in Awassi dairy ewes in southern Turkey

In order to study the prevalence and etiology of subclinical mastitis a bacteriological survey on 16 Awassi dairy sheep flocks in southern Turkey was conducted. A total of 1458 milk samples from 729 Awassi ewes in mid-lactation were tested with the California mastitis test (CMT). Samples from 170 (11.7%) glands and 135 (18.5%) sheep had positive CMT results. Bacteria were isolated from 93 (6.4%) udder halves and 82 (11.2%) ewes. Positive CMT and bacteriological results were combined to define subclinical mastitis. The prevalence of subclinical mastitis and positive CMT samples among the different flocks ranged from 1.9% to 11.5% and 2.8% to 21.9% of the glands, and 3.8% to 19% and 5.7% to 31.3% of the ewes, respectively, with averages of 6.4% and 11.7% of the glands, and 11.2% and 18.5% of the ewes, respectively. Coagulase-negative staphylococci (CNS) were the most prevalent bacteria, representing 76.5% of the isolates. Staphylococcus epidermidis (35.7%) was the most prevalent species, followed by Staphylococcus xylosus (10.2%), Staphylococcus saprophyticus (10.2%), Staphylococcus warneri (9.2%), and Staphylococcus intermedius (7.1%). Antimicrobial susceptibility of 78 Staphylococcus isolates was evaluated in this study. The most effective antibiotics were cephalothin (97.4%), sulfamethoxazole-trimethoprim (97.4%), amoxicillin + clavulanic acid (97.4%), enrofloxacin (94.9%), gentamycin (92.3%), and erythromycin (84.6%). The relationship between CMT +1 score and the Staphylococcus spp. isolation rate was statistically significant (P < 0.001). It was concluded that subclinical mastitis is not highly prevalent and it does not pose a significant health problem for milking Awassi sheep flocks in southern Turkey.

Evaluation of Udder Cisterns and Effects on Milk Yield of Dairy Ewes

Nine Manchega (0.94 L/d) and 10 Lacaune (2.07 L/d) ewes at the same stage of lactation (90 d in milk) were used to study the interbreed differences in milk yield, mammary morphological traits, and machine-milking ability. Udder traits were measured after 6h of udder filling before the start of the experiment. Cisternal area (by ultrasonography), cisternal milk (by teat cannula drainage), and alveolar milk (by machine milking after an intravenous oxytocin injection) were randomly measured 8h after milking for 2 wk consecutively either with an intravenous injection of an oxytocin receptor blocking agent (atosiban, AT) or without (control, C) to avoid the occurrence of milk letdown before milking. Lacaune ewes had greater udder depth (22.5±0.9 vs. 19.6±0.9cm) and cistern height (27.1±3.8 vs. 15.6±3.5mm), whereas Manchega ewes had longer (42.7±1.5 vs. 32.7±1.5mm) and wider teats (17.4±0.5 vs. 13.9±0.5mm). Values per half udder for Manchega and Lacaune ewes differed in cisternal area (12.8±0.7 and 23.7±0.6cm2) and cisternal milk (120±0.6 and 269±0.5mL), but not in alveolar milk (95±0.5 and 102±0.4mL), respectively. Cisternal area and cisternal milk were positively correlated (r=0.79). Ratios between cisternal and alveolar milk were 56:44 and 73:27 for Manchega and Lacaune ewes, respectively. Cisternal milk volumes obtained with the AT or C treatment were similar in Manchega (111±10 vs. 122±8mL) but differed in Lacaune ewes (239±8 vs. 299±8mL), respectively. Consequently, alveolar milk with AT vs. C was similar in Manchega (104±8 vs. 86±7mL) but different in Lacaune ewes (115±7 vs. 89±7mL). Results of this experiment confirm the need for the use of an oxytocin-blocking agent for accurate evaluation of milk contained in the udder of dairy ewes. Moreover, despite the differences in daily milk yield, alveolar milk did not vary between breeds, emphasizing the role of the cisternal more than the alveolar compartment for maximizing daily milk secretion in dairy sheep.

Intramammary antibiotic withdrawal periods for dairy goats compared to those for dairy cattle

This study investigated the withdrawal periods (WP) of two intramammary antibiotics Cloxamast LC (Intervet SA) and Spectrazol Milking Cow (Schering-Plough Animal Health) in dairy goats and compared them to those recommended for use in cattle. The WP for Cloxamast LC, measured by the Thermo Resistant Inhibitory Substances (TRIS) test, was 60 h in composite samples, 56 h in udder half samples, and the dye was visible for up to 56 h. The WP was significantly shorter than the 72 h recommended WP for use in cattle. It was however significantly longer when the 24 h safety margin (48 h) was subtracted from the recommended WP for cattle. For Spectrazol Milking Cow the antibiotics could be detected by the TRIS test for 61 h in composite samples and 59 h in udder half samples. This did not differ significantly from the recommended 60 h WP for cattle. However, it was significantly longer than that recommended for use in cattle without the 24 h safety margin. There was no significant difference in WP between infected and non-infected udder halves, while there was a weak positive correlation between WP and stage of lactation (R2 = 0.253). There was a moderate positive correlation (R2 = 0.583) between the TRIS test and the presence of dye in milk in udder half samples and between WP in both udder half and composite milk samples (R2 = 0.456). Weak to moderate positive correlations were present between milk yield and the WP in both udder half (R2 = 0.414) and composite (R2 = 0.262) milk samples. Significant differences (P < 0.001) were also observed between the milk yield of udder halves with and without palpable udder damage and between samples that tested TRIS positive and negative on both composite (P = 0.008) and udder half samples (P < 0.001). There was no significant difference between the milk yield of samples with or without dye. There was a significant difference in milk yield between infected and non-infected udder halves (P = 0.054) and a weak negative correlation between milk yield and stage of lactation (R2 = -0.379).

Value of tests for evaluating udder health in dairy goats: somatic cell counts, California Milk Cell Test and electrical conductivity

The value of electric conductivity (EC), California Milk Cell Test (CMCT) and somatic cell count (SCC) as diagnostic tools was investigated in dairy goats. Conductivity colour reading correlated with SCC. Milk samples with conductivity colour red had significantly higher SCC than those with conductivity colours green and orange (P < 0.001). There were moderate positive correlations between CMCT (R2 = 0.470), and conductivity score and CMCT and conductivity colour readings (R2 = 0.597). Conductivity scores were significantly (P< 0.001) higher during and after intra-mammary treatment with Cloxamast LC and conductivity colours were significantly different between treatment and control groups (P< 0.001). There was a weak positive correlation between conductivity colour and stage of lactation (R2 = 0.317) and a moderately positive correlation between conductivity score and stage of lactation (R2 = 0.523). A moderately negative correlation was shown between milk yield and conductivity score (R2 = -0.426) and between milk yield and conductivity colour (R2 = -0.433). Moderate positive correlations were present between CMCT and SCC (R2 = 0.689) and between CMCT and stage of lactation (R2 = 0.459). CMCT ratings were significantly different (P < 0.001) for the intra-mammary treatment groups. CMCT ratings for infected and non-infected udder halves (P = 0.008) were significantly different; as were those for infected and non-infected udder halves and for left and right udder halves separately (P= 0.010). CMCT ratings for milk samples with SCC above and below 750 x 10(3) cells per ml were significantly different (P < 0.001) as well as for milk from treated and control udder halves with SCC below or above 750 x 10(3) cells per ml (P < 0.001). CMCT was found to be more accurate for indicating the absence of mastitis than for diagnosing it. There were significant differences in log SCC between treatment and control groups, during and after treatment. Infected udder halves had significantly higher log SCC than non-infected udder halves before and after treatment, but not during treatment. There was a moderate positive correlation between stage of lactation and SCC (R2 = 0.438).

Changes in Alveolar and Cisternal Compartments Induced by Milking Interval in the Udder of Dairy Ewes

The aim of this work was to evaluate the effects of milking interval (4, 8, 12, 16, 20, and 24h) on cisternal size and milk partitioning (cisternal and alveolar) in the udders of dairy ewes. Twenty-four dairy ewes (Manchega, n=12; Lacaune, n=12) were used in a 2-wk experiment during mid-lactation. Cisternal and alveolar milk yields were measured and milk samples from each udder fraction were collected for analysis. Cisternal milk was obtained after i.v. injection of an oxytocin receptor antagonist, and alveolar milk was obtained after i.v. injection of oxytocin. Enlargement of the cisternal compartment due to milking intervals was measured by ultrasonography for each half udder. Volumes of cisternal and alveolar milk differed according to breed, being greater in Lacaune (888±43 and 338±25mL, respectively) than in Manchega ewes (316±43 and 218±25mL, respectively). Alveolar milk increased linearly to 16h in Manchega and 20h in Lacaune and remained constant thereafter. Cisternal milk accumulated linearly to 24-h milking intervals in both breeds. Cisternal area (values per udder half) increased as milking interval increased, reaching a plateau at 20h in Manchega (21±1cm2) and 16h in Lacaune (37±1cm2). Correlation between cisternal area and cisternal milk was the greatest at 8h (Manchega: r = 0.70 and Lacaune: r = 0.56). Cisternal area correlated with total milk (r = 0.80). Milk fat content varied markedly with milking intervals, increasing in alveolar milk (until 12h in Manchega, 8.90±0.18%; and 20h in Lacaune, 8.67±0.19%) and decreasing until 24h in cisternal milk (5.74±0.29% and 4.85±0.29%, respectively). Milk protein content increased in alveolar milk until 24h (Manchega, 6.46±0.11%; Lacaune, 5.95±0.11%), but did not vary in cisternal milk. Milk lactose content only decreased at the 24-h milking interval in the cisternal milk of Manchega ewes (4.60±0.04%). In conclusion, our results suggest that cisterns play an important role in accommodating secreted milk during extended milking intervals. Thus, long milking intervals could be a recommended strategy for large-cisterned dairy sheep. Evidence indicates that ultrasonography provides accurate estimations of udder cistern size and could be used as an indicator for selecting large-cisterned dairy ewes.

Effect of bromelain on milk yield, milk composition and mammary health in dairy goats

A 7 month prospective cohort study was designed to determine if feeding bromelain to dairy goats influenced the MSCC, milk yield, milk composition and the incidence of IMI. Forty-four clinically normal goats from 2nd to 6th parities were studied. Daily bromelain dosage was 7.4 grams/animal (185-mg/Kg weight). Samples for diagnostic bacteriology were collected from each udder half every 2 weeks. Samples for MSCC and composition were obtained every 42 days. Milk yield was also recorded every 42 days. Bromelain affected milk protein and fat but not MSCC, milk yield or milk lactose. Bromelain did not decrease the MSCC in healthy goats. Milk protein and fat increased in the bromelain treated group (P < 0.01), which is important for dairymen because premiums are paid milk fat and protein content. No clinical mastitis was detected in the goats for the total study period and incidence rate of subclinical IMI was 5.7%. Relative risk was 1.50 (0.28 < RR < 8.12) which means that the bromelain had no significant effect on IMI (P > 0.05). In addition, the use of pineapple by-products could be especially important in tropical countries were pineapple waste seems to be a pollution problem.

Risk factors and impacts of clinical and subclinical mastitis in commercial meat-producing sheep flocks in Quebec, Canada

We conducted a prospective observational study on clinical and subclinical mastitis in 30 commercial meat-producing sheep flocks from 2 regions of the province of Quebec, Canada. A total of 2792 ewes selected in late gestation were followed from lambing to weaning of lambs. The incidence of clinical mastitis for the total lactation period (average of 58 days) ranged among flocks from 0 to 6.6%, with a median of 1.2%. The most frequently isolated bacteria from the cases of clinical mastitis, in pure or mixed culture, were Mannheimia haemolytica (26%), Staphylococcus aureus (23%), and coagulase-negative staphylococci (17%). Incidence of clinical mastitis was higher in ewes that gave birth to 3 or more lambs and from the Estrie region, and was associated with an increase in ewe mortality, an increase in lamb mortality at the litter level, and a decrease in lamb's weaning weight for lambs born in multiple litter size or from ewes ≥4 years old. Among 354 selected ewes with clinically normal udder at the end of lactation, 28.8% had potentially pathogenic bacteria isolated from milk. The most prevalent bacteria were S. aureus (9.3%) and coagulase-negative staphylococci (9.3%). The risk of having a positive culture in at least one half was different between the two regions. Prevalence of ewes ( n = 261) with California Mastitis Test (CMT) positive result in at least one half was 24.1 and 14.9% using a cut-off of ≥1+ and ≥2+, respectively. Prevalence of culture-positive udder halves was 11.7% for CMT-negative compared with 53.6% for CMT 3+ halves. CMT status was positively associated with the isolation of coagulase-negative staphylococci, M. haemolytica, S. aureus, and various Streptococcus species, but not with other isolated bacteria. Additionally, prevalence of CMT-positive halves was higher in ewes from the Estrie region, aged of ≥4 years versus 1 year, having clinical mastitis previously detected in the lactation and/or with low body condition score. Lamb weaning weight was associated with CMT status of ewes, while weaning weight was not associated with milk culture results. More research is needed to understand the dynamic of milk SCC and IMI in ewes from meat-producing flocks, its economical impact and best ways to control it.