A cohort study of the associations between udder conformation, milk somatic cell count, and lamb weight in suckler ewes

A cohort study of 67 suckler ewes from 1 farm was carried out from January to May 2010 to investigate associations between udder conformation, udder half milk somatic cell count (SCC), and lamb weight. Ewes and lambs were observed at lambing. Ewe health and teat condition and lamb health and weight were recorded on 4 to 5 further occasions at 14-d intervals. At each observation, a milk sample was collected from each udder half for somatic cell counting. Two weeks after lambing, ewe udder conformation and teat placement were scored. Low lamb weight was associated with ewe SCC >400,000 cells/mL (−0.73kg), a new teat lesion 14 d previously (−0.91kg), suboptimal teat position (−1.38kg), rearing in a multiple litter (−1.45kg), presence of diarrhea at the examination (−1.19kg), and rearing by a 9-yr-old ewe compared with a 6-yr-old ewe (−2.36kg). High lamb weight was associated with increasing lamb age (0.21kg/d), increasing birth weight (1.65kg/kg at birth), and increasing number of days the ewe was given supplementary feed before lambing (0.06kg/d). High udder half SCC was associated with pendulous udders (9.6% increase in SCC/cm of drop) and greater total cross-sectional area of the teats (7.2% increase of SCC/cm2). Low SCC were associated with a heavier mean litter weight (6.7% decrease in SCC/kg). Linear, quadratic, and cubic terms for days in lactation were also significant. We conclude that poor udder and teat conformation are associated with high levels of intramammary infection, as indicated by increased SCC and that both physical attributes of the udder and SCC are linked to lamb growth, suggesting that selection of suckler ewes with better udder and teat conformation would reduce intramammary infection and increase lamb growth rate

A cohort study of the associations between udder conformation, milk somatic cell count, and lamb weight in suckler ewes

A cohort study of 67 suckler ewes from 1 farm was carried out from January to May 2010 to investigate associations between udder conformation, udder half milk somatic cell count (SCC), and lamb weight. Ewes and lambs were observed at lambing. Ewe health and teat condition and lamb health and weight were recorded on 4 to 5 further occasions at 14-d intervals. At each observation, a milk sample was collected from each udder half for somatic cell counting. Two weeks after lambing, ewe udder conformation and teat placement were scored. Low lamb weight was associated with ewe SCC >400,000 cells/mL (−0.73kg), a new teat lesion 14 d previously (−0.91kg), suboptimal teat position (−1.38kg), rearing in a multiple litter (−1.45kg), presence of diarrhea at the examination (−1.19kg), and rearing by a 9-yr-old ewe compared with a 6-yr-old ewe (−2.36kg). High lamb weight was associated with increasing lamb age (0.21kg/d), increasing birth weight (1.65kg/kg at birth), and increasing number of days the ewe was given supplementary feed before lambing (0.06kg/d). High udder half SCC was associated with pendulous udders (9.6% increase in SCC/cm of drop) and greater total cross-sectional area of the teats (7.2% increase of SCC/cm2). Low SCC were associated with a heavier mean litter weight (6.7% decrease in SCC/kg). Linear, quadratic, and cubic terms for days in lactation were also significant. We conclude that poor udder and teat conformation are associated with high levels of intramammary infection, as indicated by increased SCC and that both physical attributes of the udder and SCC are linked to lamb growth, suggesting that selection of suckler ewes with better udder and teat conformation would reduce intramammary infection and increase lamb growth rate

Perspectives of animal caretakers on udder edema in dairy cattle and the effects of udder edema on parlor behavior in first and second lactation dairy cattle, The

2022 Spring.Includes bibliographical references.Udder edema is a metabolic disorder in dairy cattle that results in lymphatic fluid being trapped in mammary tissues. Severe cases of udder edema can present in the brisket, navel, upper rear legs, and vulva. Known factors associated with udder edema include genetics, nutrition, oxidative stress, and high body condition score. Furthermore, as heifers are developing the mammary system during late-gestation, changes to their physiology are also occurring that influence the presentation of udder edema. Udder edema has been shown to negatively affect milk production, damage support structures of the mammary gland, and increase the risk of secondary diseases, such as mastitis and udder cleft dermatitis. With the concentration of udder edema, two studies were conducted examining dairy caretaker perspectives on udder edema and the effect udder edema has on behavior during the milk procedure. The objectives of the dairy caretaker survey were to 1) capture and evaluate current perspectives on udder edema from dairy caretakers, 2) assess caretakers' knowledge about factors that influence the development of udder edema, and 3) understand what the current monitoring practices of udder edema are on farms. The survey was distributed through an industry magazine and in a dairy exposition's electronic newsletter. A total of thirty caretakers completed the survey. The majority of dairy animal caretakers within the study agreed with the following statements: udder edema is a part of udder health, udder edema is more commonly seen in heifers (93.3%), an industry-standard rating scale would be useful to monitor udder edema (70%), it is important to be trained to identify udder edema (93.3%) , udder edema increases the risk for mastitis (73.3%), udder edema can be managed through nutrition (73.3%), udder edema negatively affects milk production (80%), high genetic milk production potential increases the risk of udder edema (70%), udder edema affects the attachment of the milking unit (90%), udder edema is painful (90%), and that udder edema is an animal welfare issue (86.7%). Currently, there is no validated scoring tool for udder edema. Based on these findings it can be concluded that the caretakers in the study feel that udder edema has a negative impact on the overall wellbeing and productive ability of their cattle. A second study was conducted to investigate the hypothesis that udder edema causes discomfort to dairy cattle during the milking session. Increased sensitivity of the teats due to udder edema may cause cows to show discomfort-related behaviors, such as stepping and kicking. First and second lactation cows (n=376) on two large Colorado farms (>500 head) were observed in the milking parlor during the udder preparation and active milking phase. All cows were visually examined and scored for udder edema at the end of the milking session. The stepping and kicking behaviors were counted to possibly identify if, at any time during the udder preparation or milking phase, cows with edematous udders showed heightened levels of rear leg behavior. First lactation dairy cattle showed an increase in stepping behavior during the udder preparation phase as compared to first lactation cows without udder edema when the milker is physically manipulating the udder (p = 0.0168). Second lactation cows with udder edema had greater step rate than first lactation cows without udder edema during udder prep when the milker was in contact with the udder (p = 0.0215). First lactation cows with udder edema have greater frequency of kick behavior compared to second lactation cows with udder edema during the milking session (p=0.0092). First lactation cows with udder edema kicked off the milking unit more often compared to first lactation cows without udder edema (p=0.0500) and second lactation cows with udder edema (p=0.0017). It was concluded that udder edema can influence a change in step and kick behavior in the milking parlor

Studies on restricted suckling in dual purpose and dairy breed cattle in Mexico

The aim of this thesis was to investigate the effects of rearing calves by restricted suckling (RS) compared to artificial rearing (AR) in dual purpose and dairy breed cattle in Mexico, milked once or three times a day, respectively. The following parameters were recorded during the first eight weeks after calving: social, abnormal and general behaviours and weight gain of Zebu crossbred and dairy calves; and milk yield, milk composition and udder health in the Zebu crossbred dams and udder health and milk let-down in the Holstein dams. RS reduced the abnormal behaviours of the calves and resulted in less foraging behaviours compared to AR. AR dairy calves consumed four-fold as much concentrate as RS dairy calves, whereas the amount of milk ingested was similar in the two treatments. A higher fat content in the milk ingested by RS calves compared to whole milk fed to AR calves, resulted in similar total ME intake from milk and concentrate in both treatments. Irrespective of type of animals RS resulted in similar weight gain in comparison to AR. Cow-calf separation five days after calving induced fewer indications of physiological stress in RS cows and calves. RS further increased the saleable and total (saleable and suckled) milk yield and decreased the fat content in saleable milk. RS improved udder health of the Zebu crossbred cows as judged according to elevated CMT scores and lower lactose content in AR cows. RS of Holstein dairy cows did not impair milk let-down and udder health tended to be improved according to the CMT. RS calves showed a front teat preference, which did not impair udder health according to similar CMT scores of front and rear teats. These studies indicate that RS is economically viable for the farmer as once daily milking combined with twice daily suckling considerably increased the saleable and total milk yield of Zebu crossbred cows and improved animal well-being

Intra-mammary molecular mechanisms involved in the response to changes in milking frequency : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Palmerston North, New Zealand

In dairy cows, short-term changes of milking frequency (MF) in early lactation have been shown to produce an immediate and a long-term effect on milk yield (MY). The effect is controlled locally within the mammary gland by as yet unknown factors. To investigate the intra-mammary molecular mechanisms that are involved in the MY response to MF, a unilateral milking frequency (UMF) experiment was conducted with udder halves of 17 multiparous pasture-fed dairy cows milked either four times a day (4x) or once a day (1x) for fourteen days from 5 ± 2 days in milk (DIM). Mean udder-half MY during the treatment period was higher from the 4x compared to 1x-udder halves and once returned to twice a day milking, continued to be higher until 200 DIM. Mammary biopsies were obtained on day fourteen of treatment from both udder halves of ten cows. Proliferation of mammary cells was higher in 4x-udder halves compared to 1x, whereas no difference in apoptosis levels was detected. Abundance of major milk protein gene mRNA was higher in tissue samples from 4x-udder halves compared with 1x. The effects of changes of MF in early lactation on the prolactin (PRL) and insulin-like growth factor I (IGF-I) pathways to determine their role in the MY response to MF. The activation of signal transducer and activator of transcription (STAT) 5 was measured as an indication of PRL signalling, which was higher following 4x-milked mammary tissue samples compared to 1x-milked, and correlated highly with milk protein gene mRNA abundance. Activation of STAT5 also correlated with the protein abundance of the extracellular matrix (ECM) interacting protein β1-integrin, which suggest a link between PRL/STAT5 and ECM/β1-integrin signalling. The mRNA abundance of IGF binding protein (IGFBP)3 and IGFBP5 were lower in 4x-milked mammary tissue samples relative to 1x-milked. Both IGFBP3 and IGFBP5 are thought to inhibit IGF-I, so the decrease in their mRNA abundance may serve to stimulate the IGF-I signal in the 4x-milked mammary gland. However, two cellular pathways downstream of IGF-I (phosphoinositide 3-kinase (PI3K)/Akt and extracellular-signal-regulated kinase (ERK)1/2) were not positively affected by 4x milking. The activation of PI3K/Akt pathway was lower in 4x-milked mammary tissue samples relative to 1x-milked, and the activation of the ERK1/2 was unaffected by MF. Overall, the results obtained in this thesis have increased the understanding of the changes in intra-mammary molecular mechanisms in response to differing MF

Evaluation and optimal utilisation of the international linear type classification schemes

End of project reportThe authors would like to acknowledge the Irish Cattle Breeding Federation for access to their excellent database for use in this study and to the Irish Holstein-Friesian Association for financial support of this studyThe main objectives of this study were: 1) to evaluate the phenotypic associations between linear type traits and survival in New Zealand and identify potential new traits for inclusion in the type classification scheme in Ireland, and 2) to quantify the potential of linear type traits scored in Ireland as early predictors of genetic merit for fertility and survival in Ireland

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 bacterio-logical 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

An evaluation of traits other than production and its association with the survival of dairy cows milked once a day in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of AgriScience at Massey University, Palmerston North, New Zealand

New Zealand dairy cows have traditionally been milked twice a day (TAD). However, an increasing number of dairy farms have shifted to once a day (OAD) milking in the last few years for several reasons. A particular emphasis has been placed on the cow’s conformation and its management during the milking routine in OAD dairy farms, as these factors might have altered the culling decisions of herds after shifting from TAD to OAD milking. This thesis evaluates production traits and traits other than production (TOP) in the herd of Massey University Dairy 1 since the start of OAD milking and for three consecutive seasons (2013- 2015), with an assessment of the influence that these traits have on the cow’s survival. Results showed a significant effect of breed, season and lactation on TOP. The scores for most udder traits showed a gradual decrease over lactations. The main reasons for culling were low fertility (37.2%), poor udder conformation (19.9%) and low production (12.8%). Hazard ratios from a Cox proportional hazard model showed that Holstein-Friesian and crossbred cows had a higher likelihood of culling than Jerseys, which also had the highest scores for most udder traits. For some TOP, such as adaptability to milking, rump angle and udder support, higher scores were associated with a lower likelihood of culling. However, intermediate scores were optimum for traits such as body capacity and leg conformation. The results of this thesis are the first to show culling reasons and risk factors for survival in cows recently shifted from TAD to OAD. The analyses of TOP over seasons and over lactations are also unique to this thesis as most studies on this topic only include TOP on first lactation cows. The findings of this thesis indicate that TOP would have a higher priority to make culling decisions in OAD herds during the transition from TAD to OAD milking, compared to TAD herds and also established OAD herds that have used this milking frequency for several seasons. Furthermore, besides body capacity and udder support, traits such as adaptability to milking, rump angle and leg conformation could also potentially be included in a new selection index for OAD dairy cattle