Four studies were conducted to evaluate the effects of supplemental cooling and niacin on heat stress (HS) responses in vivo and in vitro in lactating dairy cows. For experiment one, lactating dairy cows were fed four levels of dietary niacin, NIASHURE® (0,4,8,12 g/d) for 21 d. Heat stress decreased niacin levels in whole blood, red blood cells and plasma as compared to thermoneutral. Water intake, plasma and milk niacin concentrations increased linearly with increasing dietary niacin in HS cattle. In thermoneutral, but not HS cows, niacin increased skin temperature compared to controls suggesting niacin increased skin blood flow and sensible heat loss. In experiment 2, lactating cows were used to evaluate the impact of feed-line soaking (FLS) combined with niacin supplementation. In evaporative cooled barns, FLS reduced body temperatures; however the addition of niacin did not improve heat status of these cows. For experiment 3, 200 lactating dairy cows were used to determine the effects of conductively cooled bedding (CC) compared to feed-line soaking with fans (FLSF). Conductively cooled bedding can reduce skin and vaginal temperatures in cows after nighttime rest. However, FLSF were more effective in decreasing body temperature, as cows had lower heat parameter indices, higher milk yield and longer rest time. For experiment 4, three cell types were used to evaluate niacin in vitro. Niacin induced heat shock proteins (HSP) that protected cells during HS in transformed bovine mammary epithelial cells but not in primary bovine mammary epithelial cells (BMEC) or bovine endometrial cells (BEND). Effect of niacin on HSP may depend on enzymes involved in DNA-binding activity of heat shock factor 1. These results suggest that niacin may be involved in whole body metabolism during heat stress and is cell dependent. We did not find dietary niacin to be commercially efficacious in treating HS in cows. Further research is warranted to improve efficacy of CC and FLSF under high temperature humidity index conditions.

This study was conducted to: i) determine the effect of residual feed intake (RFI) on first parity fertility and subsequent lifetime productivity of 820 females ranked as low, medium, and high RFI in western Canada and ii) investigate the relationship between RFI measured as a heifer and re-measured as a mature cow. No significant correlations were found between RFI and fertility/productivity traits. A negative trend (P < 0.10) was observed between RFI, RFIfat and MPPAbw, however, this trend was no longer apparent when RFI was adjusted for back fat and feeding event frequency (RFIfat&activity). No significant (P < 0.05) relationship was found between heifer RFI and cow RFI. These results suggest that selection for feed efficient, low RFI heifers i) has no impact on their fertility and productivity as cows, and ii) may not lead to superior feed efficiency as a mature cow as measured by RFI and Cow DMI. / February 2017

Durante o puerpério há muita incidência de doenças reprodutivas acarretando aumento do intervalo entre partos, bem como diminuição na taxa de concepção. A endometrite é uma enfermidade puerperal que se caracteriza por um processo inflamatório superficial do endométrio. Com o intuito de se obter novas ferramentas diagnósticas não invasivas, precisas e que proporcionam resultados precoce à reprodução, faz-se uso da ultrassonografia convencional associada a ferramenta Doppler que fornece informações em tempo real sobre a arquitetura vascular e os aspectos hemodinâmicos dos vasos em diversos órgãos. Este estudo tem por objetivo descrever, através da ultrassonografia Doppler, as alterações hemodinâmicas no útero de fêmeas bovinas causadas pela endometrite. Avaliou-se o trato reprodutivo feminino de vacas entre 25 a 35 dias pós-parto utilizando a vaginoscopia, ultrassonografia convencional e Doppler, além de citologia e exame microbiológico em 89 vacas Holandesas sendo 33 sadias (controle) e 56 com endometrite diagnosticadas por citologia (saudáveis &lt;10% de polimorfonucleares). Os resultados obtidos destacam-se a que animais com endometrite apresentavam aumento de cérvix (p=0,04), e de útero representado pelo corno esquerdo (p=0,02). Porém não foi observado diferença quando comparado os escore de condição corporal (ECC). Quanto a ultrassonografia notou-se que animais com fluido intrauterino (FIU) e conteúdo heterogêneo intrauterino (CHIU) tinham endometrite (p&lt;0,0001), além de correlação com a presença de Trueperella pyogenes e leveduras. Com o modo cores do Doppler obteve-se a vascularização de mesométrio (p=0,004) e endométrio (p=0,025) associada aendometrite. Entretanto não foi observado diferença estatística nas medidas do Doppler espectral (índice de resistividade, pulsatilidade e fluxo sanguíneo). Portanto a busca de novas técnicas, menos invasivas e de rápido resultado, como a ultrassonografia Doppler, podem fornecer respostas satisfatórias quanto a evolução de alterações uterinas e com isso associar os resultados à precocidade reprodutiva. / During the puerperium period there is a high incidence of reproductive diseases resulting in increased calving interval and decrease in conception rate. The endometritis is a postpartum disease that is characterized by a superficial inflammation of endometrium. With the aim to obtain new non-invasive and accurate diagnostic tools, that provide early results in reproduction, it is possible to be used the conventional ultrasound associated to Doppler that provides real time information about vascular architecture and hemodynamic aspects of vessels in several organs. This study aims to describe, through Doppler ultrasound, hemodynamic changes in the uterus of cows caused by endometritis. Were evaluated the female reproductive tract of 89 Holstein cows between 25 to 35 days postpartum using vaginoscopy, conventional ultrasound and Doppler, as well as cytology and microbiological examination. From the 89 animals that were studied, 33 were healthy (control) and 56 with endometritis diagnosed by cytology (healthy &lt;10% polymorphonuclear). The obtained results show that animals with endometritis had increase in cervix (p = 0.04) and the uterus represented by left uterine horn (p = 0.02). However, it was not detected difference when compared the body condition score (BCS). About the ultrasound was noted that animals with intrauterine fluid (IUF) and intrauterine heterogeneous content (IUHC) had endometritis (p &lt;0.0001) correlation with the presence of Trueperella pyogenes and yeasts. With the color Doppler mode it was possible to obtain the vascularization of mesometrium (p = 0.004) and endometrium (p = 0.025) associated with endometritis. However, it was not observed statistical difference in the measurements of the spectral Doppler (resistance index, pulsatility and blood flow). Therefore, the search for new techniques, less invasive and fast result, as the Doppler ultrasound can provide satisfactory answers as the evolution of uterine changes and thereby associate the results to the reproductive precocity.

Submitted by Marcos Anselmo (marcos.anselmo@unipampa.edu.br) on 2018-09-28T18:53:23Z No. of bitstreams: 1 JANICE MACHADO DE MACHADO VILLELA.pdf: 769666 bytes, checksum: 37e9705b299aec59293356729fda9547 (MD5) / Approved for entry into archive by Marcos Anselmo (marcos.anselmo@unipampa.edu.br) on 2018-09-28T18:53:35Z (GMT) No. of bitstreams: 1 JANICE MACHADO DE MACHADO VILLELA.pdf: 769666 bytes, checksum: 37e9705b299aec59293356729fda9547 (MD5) / Made available in DSpace on 2018-09-28T18:53:35Z (GMT). No. of bitstreams: 1 JANICE MACHADO DE MACHADO VILLELA.pdf: 769666 bytes, checksum: 37e9705b299aec59293356729fda9547 (MD5) Previous issue date: 2018 / O parto é uma importante fase do sistema produtivo leiteiro, e impõe grande desafio para a vaca. Além do risco de doenças clínicas e subclínicas, favorecidas pela imunossupressão e alterações hormonais, as vacas podem sofrer distocias, que são partos marcados por dificuldade, tempo prolongado e necessidade de assistência para remoção do feto. Por ser multifatorial, além das causas maternas e fetais relacionadas à distocia, pode haver interação com variáveis comportamentais, ambientais e de manejo. O impacto da distocia no sistema produtivo está relacionado à ocorrência de doenças, o que aumenta o risco de descarte e morte, tanto para as vacas quanto para suas crias, impactando nos custos de produção e afetando a composição e longevidade do rebanho. Portanto, a presente dissertação teve como objetivos: identificar os fatores de risco associados à distocia e seu impacto sobre as doenças do período de transição pós-parto e sobre a produção de leite em vacas leiteiras; e avaliar se bezerras leiteiras nascidas de partos distócicos tiveram seu desenvolvimento, saúde, reprodução e produção de leite prejudicados. Para responder aos objetivos, realizou-se um estudo observacional retrospectivo utilizando registros de uma propriedade leiteira no Rio Grande do Sul, obtidos do software de gerenciamento leiteiro Dairy Plan C-21(GEA). O estudo foi dividido em dois experimentos, cujos resultados estão em um artigo científico. Para responder a um dos objetivos do primeiro experimento, foram analisados dados de 1.001 partos de vacas Holandesas, primíparas e multíparas, ocorridos entre 2013 e 2017, agrupadas em partos eutócicos e distócicos. As variáveis incluídas como preditoras de risco de distocia foram idade da vaca, categoria da vaca (primípara vs multípara), distocia ao nascimento, sexo do bezerro, tipo de parto, viabilidade do bezerro, estação climática no parto e ano. Para determinar o impacto da distocia sobre as doenças do pós-parto e produção de leite, foram analisados separadamente os dados das vacas primíparas (n= 540) e multíparas (n=461). Foram avaliadas as taxas de doenças clínicas como mastite, metrite, retenção de placenta e outras, bem como o número de episódios ocorridos, além das taxas de descarte e morte. A incidência de partos distócicos foi de 10,4% e os fatores de risco significativos para ocorrência de distocias foi o nascimento de bezerros machos, gêmeos, natimortos e partos ocorridos no inverno. Observou-se uma alta taxa de doenças clínicas no pós-parto e um risco aumentado para desenvolvimento de metrite em vacas multíparas distócicas. Para responder ao objetivo do segundo experimento, foram analisados registros de 447 bezerras nascidas na propriedade entre 2012 e 2015 agrupadas como nascidas de partos eutócicos ou distócicos. O impacto da distocia sobre a saúde, desenvolvimento e produção das bezerras foi analisado mediante avaliação dos dados de peso ao nascimento, 30 e 60 dias de idade, ocorrência de doenças até os 60 dias e até os 365 dias de idade, bem como o número de eventos ocorridos nestes períodos e as taxas de mortalidade e descarte. Também se avaliou o número de inseminações por concepção, a idade ao primeiro parto, taxas de distocia e natimortos, as doenças clínicas mastite, metrite, retenção de placenta e outras ocorridas após o primeiro parto e a produção de leite na primeira lactação. Observou-se que bezerras crias de partos distócicos apresentaram maiores taxas de metrite após o primeiro parto. Outros parâmetros não foram afetados pela distocia. / Parturition is an important process of the dairy production system and imposes a great challenge to the cow. In addition to the risk of clinical and subclinical diseases favored by immunosuppression and hormonal changes, cows may suffer from dystocia, which are difficulty deliveries with prolonged time and sometimes the need for assist in fetal removal. Since it is multifactorial, in addition to the maternal and fetal causes related to dystocia, it could have interaction with behavioral, environmental and management variables. The impact of dystocia on the productive system is related to the occurrence of diseases, which increases the risk of discarding the cows from the dairy and even death of the cows and their offspring, impacting production costs and affecting the composition and longevity of the herd. Therefore, the present dissertation had as objectives: identify the risk factors associated with dystocia and its impact on the diseases of the postpartum transition period and on milk production in dairy cows; and evaluate if dairy heifers born from a dystocic birth had their development, health, reproduction or milk production impaired. In order to respond to the objectives, a retrospective observational study was carried out using records from a dairy farm in Rio Grande do Sul, using Dairy Plan C-21 dairy management software (GEA). The study was divided into two experiments, which the results were published in a scientific paper. In order to achieve one of the objectives of the first experiment, data collected between 2013 and 2017, from 1,001 primiparous Holstein’s heifers and multiparous Holstein’s cows, grouped into normal or difficult birth was analyzed. The variables included as predictors of risk of dystocia were age, category (primiparous vs. multiparous), dystocic birth, calf sex, type of delivery, calf viability, climatic season at calving and year. To determine the impact of dystocia on postpartum diseases and milk production, data from primiparous cows (n = 540) and multiparous cows (n = 461) were analyzed separately. Rates of clinical diseases such as mastitis, metritis, retained placenta and others, as well as the number of episodes occurred and rates of discard or death were evaluated. The incidence of dystocia was 10.4% and the significant risk factors to the occurrence of dystocia were the birth of male calves, twins, stillbirths and births during winter time. There was a high rate of postpartum clinical disease and an increased risk of developing metritis in distocic multiparous cows. In order to achieve the second experiment, we analyzed the records from 447 calves born at the farm between 2012 and 2015 and grouped as born from normal or difficult births. The impact of dystocia on the health, development and production of heifers was analyzed by weight at birth, 30 and 60 days of age, occurrence of diseases up to 60 days and up to 365 days of age, as well as the number of events occurred in these periods and mortality and discharge rates. The number of inseminations per conception, age at first calving, dystocia and stillbirth rates, clinical mastitis, metritis, retained placenta and others after first calving and milk production at the first lactation were also evaluated. It was observed that heifers born from a dystocic parturition had higher rates of metritis on their first calving. Other parameters were not affected by dystocia.

For the modern dairy cow, advances in genetics and breeding for productivity has resulted in an increasing incidence of health disorders and reduced longevity. One of the most important health problems is lameness, which has led to significant economic, production and welfare consequences. A reduction in lameness will improve the economic future of the dairy industry through increased profitability and decreased welfare-related problems. Although positive attempts have been made by researchers and the industry towards improving lameness, it has remained a persistent ailment for dairy farmers. Further analysis of the genetic and environmental factors influencing lameness is warranted so that selection indices and management practices can be modified leading to improved health and welfare of the dairy cow. Several factors that cause dairy cow lameness have been implicated. I reviewed previous studies on these causative factors as well as the association between lameness, longevity and fertility. It has also been suggested that lameness affects milk production of dairy cows, but reports on the association between lameness and daily milk yield of cows have varied among researchers. Using locomotion score data on 248 cows from the Langhill herd, I investigated the relationship between locomotion score which has a high genetic correlation with lameness and various explanatory variables and also the association between daily milk yield and lameness. The study revealed that the most significant factors affecting locomotion are management regime (high concentrate feed and all year indoor housing; low concentrate feed and outdoors in summer) and time of year when cows are locomotion scored. It also showed that lameness adversely affects the milk yield of later lactation cows, and that high yielding cows are more susceptible to lameness. Housing environment plays a significant role in the health and welfare of dairy cows. With national type evaluation records, I estimated the association between housing systems and lameness-related type traits as well as genetic parameters for the locomotion traits. The analysis indicated that cows kept at pasture had favourable linear and composite type trait scores compared with cows in cubicles, straw yards and slatted floors or loafing yards. Locomotion score had strong genetic and phenotypic correlations with the leg and feet composite. Bone quality, which is a new trait in the UK type classification scheme, was moderately heritable (0.23) and had a moderate and positive genetic association with locomotion and leg and feet composite. This suggests that breeding for flatter, more refined bones could reduce locomotion disorders and help improve the longevity of the dairy cow. Analysis of national data again showed reduced incidence of digital dermatitis (DD) for cows at pasture and those with flatter, more refined bones, higher locomotion score and better leg and feet composite. Estimates of genetic parameters indicated heritable variation of DD among cows and moderate genetic associations between DD and production traits and longevity. Incorporating DD in future selection indices will be useful for increased productive life. Using random regression, I analysed changes in type traits associated with lameness (locomotion, rear legs, side view, foot angle and leg and feet composite) in relation to time (months) that cows had spent in cubicles before being classified. The general trend supported the fact that cubicle housing is unfavourable to these traits. There was significant evidence of a genotype x environment interaction, suggesting variation between bulls in the sensitivity of their daughters to cubicle housing with time.

Pasture is considered one of our most important agricultural crops, contributing more than one third of all feed consumed by livestock in the United States. High quality pasture has been recognized to be highly important in efficient milk production. It has been shown, however, that good pasture must be supplemented by concentrates if' milk production is to be maintained at a high level.

Previous studies of dairy cattle have indicated that heifers and cows in hot, cold and moderate weather had different patterns of sexual activities. The purpose of this study was to compare distribution of sexual activities within estrus of dairy cattle. Three groups of lactating cows in hot, cold and moderate weather and a group of heifers in cold weather were observed. Estrus for each individual was divided into 12 equal periods. Sexual activities for 3 and 6 hours before and after estrus were also observed. The numbers of mounts and distribution of total sexual activities was analyzed. Mounts received per animal per period for all four groups were significantly different. Heifers had significantly more mounts than cows with 5.8 mounts per animal per period. Cows in hot weather had significantly less mounts than other groups with 1.2 mounts per animal per group. Cows in cold and moderate weather had similar numbers of mounts with 2.9 and 2.4 mounts per animal per period, respectively. This was significantly fewer mounts than were received by heifers but a significantly higher number of mounts than received by cows in hot weather. There was much individual variation; however, the distribution of mounts and activities per period did not significantly differ across groups. There were trends for cows in hot weather to have rest periods within estrus where less mounting occurred. Secondary sexual activities before and after standing estrus were less intense than during estrus. Secondary sexual activities were greater in the three hours before and after estrus compared to the three to six hours before and after estrus.

The cattle shown from 1981 to 1984 at the American Angus Breeders' Futurity were studied to determine the relationship between linear measurements and the judge's subjective placings. Linear measurements taken prior to the showing included wither height, hip height, and body length for both bulls and heifers. In addition body weight and scrotal circumference were recorded for bulls. A total of 624 cattle were studied-- 407 heifers and 217 bulls. The cattle were divided into five groups by age and sex to analyze the annual difference in means and standard deviations for all recorded measurements. Among all five groups of cattle, hip height increased at the fastest rate from 1981 to 1984. All measurements had a positive increase except body weight and scrotal circumference. The older bulls decreased by 61.67 lbs. in weight from 1981 to 1984 and decreased by 1.78 in. in scrotal circumference between 1983 and 1984. Coefficients of correlation were obtained using the recorded measurements along with age for all five groups. Wither height showed the closest association to other measurements. Among all five groups body length had the most inconsistent association to other measurements, primarily due to difficulty involved in obtaining an accurate body length measurement. Spearman's coefficient of rank correlation was conducted to determine which measurements the judges were giving most emphasis in the showring. It seems apparent that judges are continuing to select for larger framed cattle, placing greater emphasis on wither and hip height measurements and lesser emphasis on body weight and scrotal circumference. The findings in this study support the fact that judges are selecting for larger framed, later maturing cattle with little if any selection being placed upon present weight or indicators of future reproductive performance.

The calves born in the 1979 and 1980 calf crops at Sam Sells and Sons' Polled Hereford Farm in Moultrie, Georgia, were used in a study comparing immature body measurements with subsequent growth. The measurements taken at birth included weight, front leg length, front cannon bone length, and rear cannon bone length. In addition, hip height was measured at one hundred days, seven months, and twelve months of age. Weight was taken at seven months, twelve months and fifteen months of age. The data were analyzed in four groups according to year of birth and sex. Coefficients of correlation were determined for all measurement combinations. Birth measurements alone accounted for an insignificant amount of the variability in twelve-month weight. Among the four groups studied, seven-month weight showed inconsistent associations to height and weight at twelve and fifteen months of age. This was due primarily to the amount of environmental influences involved in weight at seven months. Multiple regression analyses were conducted using twelve-month weight as a dependent variable and immature body measures as independent variables. An equation using one hundred-day hip height alone accounted for seventy-six percent of the variability in twelvemonth weight. Another equation including two independent variables, one hundred-day hip height and seven-month weight, accounted for eighty percent of the variability in twelvemonth weight. When twelve-month height was used for a dependent variable, one hundred-day hip height and rear cannon bone length at birth accounted for seventy percent of the variability. The coefficients of correlation and multiple regression equations reported in this study support the fact that linear measurements are a more consistent measure of size in immature calves than weight alone. Also, linear measurements show little or no variation due to environmental conditions such as age of dam, unpartitioned maternal ability and physiological changes associated with puberty. The findings support the hypothesis that immature linear skeletal measurements are accurate predictors of subsequent growth in Polled Hereford cattle.

Thirty-six multiparous Holstein cows were assigned to one of three dietary levels of lasalocid· 0, 180, or 360 mg/hd/d in a completely randomized design Cows were assigned to treatments I wk postcalving and remained on treatment until II wk postcalving Basal diets were composed of ground corn, alfalfa hay, alfalfa haylage, corn silage, and soybean meal, fortified with vitamins and minerals as needed. All ingredients were ground and fed as a total mixed ration Daily rations were fed in two equal portions at 0500 and I 700 h at a rate to allow a 5- 10% refusal. Daily measurements included milk production and dry matter intake (OM 1). Milk composition (fat, protein, and somatic ii cells) was analyzed twice per week on Tuesdays and Fridays. Cow body weight (BW) and visual body condition were measured weekly. Production during previous lactation was used as a covariate in analyzing the data. Although milk production was not affected by dietary treatment, lasalocid tended to increase daily milk production by approximately 2.5 kg/d (P 13) at both the 180 and 360 mg/hd/d levels Percent milk fat and protein were not afl'ected by dietary lasalocid (P 84 and 78, respectively). Somatic cell count of the milk was not affected by dietary lasalocid (/' 17). Dietary lasalocid reduced DMI by approximately I 5 kg/d at both the 180 and 360 mg/hdld levels (P .02). At the 180 and 360 mg/hdld levels, lasalocid increased amount of milk produced per kg of DM consumed by 16 kg (I' 08). either BW (P 89) nor body condition (P = 90) were affected by dietary lasalocid at either level. No effect of treatments was observed on blood metabolites Glucose, nonesterified fatty acids, P-hydroxybutyrate, and cholesterol all tell within the normal ranges of blood serum.