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Author: Amanda Jillian Cain Publisher: ISBN: Category : Languages : en Pages : 102
Book Description
The objective of the present study was to evaluate the effects of low input development protocols on Southeastern replacement beef females and their offspring. Fall and spring calving crossbred beef heifers managed through one of two heifer development programs (low input, LOW or conventionally developed, CON) were evaluated for metrics of uterine artery hemodynamics, patterns of heifer and offspring growth, postpartum reproductive performance, and economic efficiency. There were significant treatment × season (P = 0.0001) and season × day (P = 0.003) interactions on heifer body weight (BW) during gestation. There was a season × day interaction on total blood flow (TBF; P = 0.05) whereby TBF increased as gestation progressed and spring calving heifers displayed increased TBF. When adjusted for BW, an additional main effect of treatment was observed (P = 0.0007) in which LOW heifers had increased TBF compared to CON heifers. There were no significant main effects of treatment or season or interactions thereof on the proportion of females cycling at the start of the breeding season (P > 0.05). Additionally, there were main effects of treatment (P = 0.0095; P = 0.02) and season (P = 0.012; P = 0.007) on calf ADG and weaning weights, respectively whereby calves born to CON females grew faster than calves born to LOW heifers, and SPRING calves gained more rapidly than FALL calves. Partial budgeting demonstrated that LOW bred heifers were $250/hd less expensive to purchase than CON heifers due to lighter BW. Calves born to LOW females yielded $6.38 less per calf compared to CON calves. The discrepancy in reproductive efficiency coupled with the failure of LOW females to achieve BW similar to CON females resulted in a difference of $403/hd in average cull value between LOW and CON females in which CON females were worth more. Thus, CON females were $159.18 more profitable than LOW females when purchased as bred heifers and sold at the weaning of their first calf. In conclusion, though uterine artery BF was not negatively affected, low input heifer development resulted in sub-optimal heifer growth, poor first calf performance, and inadequate reproductive efficiency.
Author: Amanda Jillian Cain Publisher: ISBN: Category : Languages : en Pages : 102
Book Description
The objective of the present study was to evaluate the effects of low input development protocols on Southeastern replacement beef females and their offspring. Fall and spring calving crossbred beef heifers managed through one of two heifer development programs (low input, LOW or conventionally developed, CON) were evaluated for metrics of uterine artery hemodynamics, patterns of heifer and offspring growth, postpartum reproductive performance, and economic efficiency. There were significant treatment × season (P = 0.0001) and season × day (P = 0.003) interactions on heifer body weight (BW) during gestation. There was a season × day interaction on total blood flow (TBF; P = 0.05) whereby TBF increased as gestation progressed and spring calving heifers displayed increased TBF. When adjusted for BW, an additional main effect of treatment was observed (P = 0.0007) in which LOW heifers had increased TBF compared to CON heifers. There were no significant main effects of treatment or season or interactions thereof on the proportion of females cycling at the start of the breeding season (P > 0.05). Additionally, there were main effects of treatment (P = 0.0095; P = 0.02) and season (P = 0.012; P = 0.007) on calf ADG and weaning weights, respectively whereby calves born to CON females grew faster than calves born to LOW heifers, and SPRING calves gained more rapidly than FALL calves. Partial budgeting demonstrated that LOW bred heifers were $250/hd less expensive to purchase than CON heifers due to lighter BW. Calves born to LOW females yielded $6.38 less per calf compared to CON calves. The discrepancy in reproductive efficiency coupled with the failure of LOW females to achieve BW similar to CON females resulted in a difference of $403/hd in average cull value between LOW and CON females in which CON females were worth more. Thus, CON females were $159.18 more profitable than LOW females when purchased as bred heifers and sold at the weaning of their first calf. In conclusion, though uterine artery BF was not negatively affected, low input heifer development resulted in sub-optimal heifer growth, poor first calf performance, and inadequate reproductive efficiency.
Author: Ricardo P. Arias Publisher: ISBN: 9780355855951 Category : Beef cattle Languages : en Pages : 129
Book Description
The effects of nutrition during late gestation and after insemination, as well as the effects of energy reserves on reproductive function of the beef female and subsequent growth and reproductive function of their offspring were investigated. The aims of this research were: 1) to evaluate how a change in nutritional intake immediately after insemination would affect pregnancy success and concentrations of hormonal mediators, IGF-I and progesterone, 2) to determine the influence that postpartum energy reserves have on embryo viability, early embryonic development, and embryo quality, and 3) to evaluate the impact that maternal protein supplementation of irrigated meadow grass hay during the last trimester of gestation has on cow BW and BCS, calf birth and weaning BW, conception rates of heifer offspring, and feedlot performance of steer offspring. Findings from Chapter III show that suppression in nutritional plane of heifers during the 21-d following AI has a negative impact on heifer performance, circulating concentrations of IGF-I, and AI pregnancy rates. Thus, it is biologically beneficial to ensure that heifers maintain their pre-breeding plane of nutrition during the 21-d following AI. Chapter IV presents evidence that cows with BCS 5.4 tend to produce more total embryos after a superovulation program compared to cows BCS 4.3. Additionally, peripheral concentrations of IGF-I were greatest in cows with a BCS 5.4, which may be an indicator of a more suitable environment in the uterus for further development of an embryo. In Chapter V, cows supplemented with protein during the last trimester of gestation had a greater BW gain and BCS change by calving time. Weaning BW of calves born to protein supplemented dams was greater when compared to calves from non-supplemented cows. There was a trend for pregnancy rates of heifers born supplemented dams to be 16 percentage points greater (95% vs. 79%). And although dam supplementation did not seem to affect intakes, gains, feed efficiency or carcass characteristics on the male progeny in this study, advantages have been observed other peer-reviewed research studies that support the concept that late gestation supplementation can have an impact subsequent progeny.
Author: Katylyn Jo Richardson Publisher: ISBN: Category : Cattle Languages : en Pages : 0
Book Description
A series of studies were completed to determine if reproductive efficiency and offspring performance could be improved through the implementation of a novel method of embryonic selection and the proliferation of a desirable genotype in cattle. The first study evaluated the effectiveness of an Embryo Chamber to distinguish between viable and nonviable bovine embryos based on specific gravity of the embryo. In this study, 19 in vitro produced (IVP) and 15 in vivo derived (IVD) Grade 1 embryos were individually placed into a 0.5 mL semen straw of media and allowed to descend through the Embryo Chamber. Descent time through a vertical, one-centimeter timing region was recorded, and embryos were removed from the chamber and either transferred into recipient females or cryopreserved and transferred at a later date. In order to determine if Embryo Chamber evaluation had an effect on pregnancy status, 27 IVP and 12 IVD, Grade 1 embryos that were not evaluated with the Embryo Chamber were also transferred into recipient females at the time of project embryo transfer. Pregnancy was later determined via rectal ultrasound and recorded. There was no significant difference in conception rates between embryos evaluated with the Embryo Chamber and those not evaluated with the Embryo Chamber, indicating that chamber analysis had no negative impact on viability of both IVP (P = 0.54) and IVD (P = 0.93) embryos. Of the 34 total embryos evaluated with the Embryo Chamber, 22 resulted in successful implantation and pregnancy, with 13 pregnancies (68.4%) by IVP embryos and 9 (60%) by IVD. There was no difference in average descent time of pregnant and non-pregnant embryos for IVP (P = 0.54) or IVD embryos (P = 0.24). When divided into groups according to descent time, 32% of all observations for IVP embryos occurred between 30 to 50 s with a 66.7% conception rate, and 42% occurred between 70 to 90 s with a 75% conception rate (P = 0.85). For IVD, 60% of all observations occurred between 90 to 110 s, with a conception rate of 66.7% (P = 0.35). Analysis of the correlation between descent group and pregnancy outcome or descent time and pregnancy outcome showed no strong correlation for either production method. Though not significant, the trends highlighted in this data lend support to previous research with variations of the Specific Gravity Device. Further research is needed to thoroughly evaluate the potential of this technology as a method of noninvasive assessment of embryo quality. The second study evaluated the merit of an F1 USDA Prime, Yield Grade 1 carcass clone sire as a terminal sire in the beef x dairy production system. In this study, the clone sire, AxG1, and a purebred Angus reference sire, Foundation, were bred to dairy cows (n = 1,430) at a commercial Jersey dairy in the Texas Panhandle. Performance data from resulting offspring of these matings was collected and analyzed to assess differences in performance between the two sires. Post-partum dam data was also collected to determine if there were any negative impacts of sire on the subsequent reproductive performance of the dams. Conception rates were 39% for AxG1 and 30% for Foundation (P
Author: Alicia Caitlin Lansford Publisher: ISBN: Category : Beef cattle Languages : en Pages : 214
Book Description
The objective of these 4 studies was to evaluate the effects of management decisions on reproductive performance of beef females. Experiment 1 evaluated the efficacy of a novel s.c. prostaglandin F2a injection on estrus synchronization and pregnancy success in yearling beef heifers. Heifers receiving a 2 mL s.c. injection of Lutalyse HighCon had similar estrus response and pregnancy rates compared to 5 mL Lutalyse i.m. within 2 different estrus synchronization programs. In experiment 2, May-calving heifers and primiparous cows were allotted to receive either no supplementation or supplement (0.45 or 0.91 kg/d per animal, heifers or primiparous cows, respectively) throughout the breeding season. Although supplementation increased BW, pregnancy rates were not impacted. In experiment 3, May-calving females were allotted to graze either sub-irrigated meadow or upland range throughout the breeding season. No differences in pregnancy rate were detected, despite differences in BW and BCS gain over the breeding season. Finally, experiment 4 examined the effects of varying levels of late gestation nutrition on dam and subsequent progeny performance. Multiparous, May-calving dams were allotted to graze either meadow or range forage and then to receive either no supplement or 0.45 kg/d per cow of a 33% CP supplement during late gestation. Prepartum meadow grazing tended to increase dam rebreed pregnancy rates. Heifer progeny had increased rebreed pregnancy rates as a primiparous cow, and steer progeny had increased marbling score if their dam grazed meadow. Dam supplementation increased BW of progeny over 2 generations. In summary, these experiments demonstrate the following findings: 1) a higher concentrate s.c. injection of prostaglandin F2a is effective in synchronizing estrus of beef heifers, 2) supplementation or differing forage type during the breeding season of a May-calving herd does not impact reproductive response, and 3) differences in late gestation nutrition of a May-calving herd results in altered progeny growth and performance.
Author: Philip C. Garnsworthy Publisher: Nottingham Trent University ISBN: 1904761224 Category : Technology & Engineering Languages : en Pages : 352
Book Description
This volume considers every aspect of calf rearing, from physiological principles to practical systems. Topics include physiology of growth and digestion, nutrient requirements, health and welfare, and lifetime performance. More than half the authors are from outside the UK and all are acknowledged as international experts in their field. This book is aimed at technical advisers, researchers, extension workers, veterinary practitioners, progressive farmers, academics and students.
Author: Richard M. Hopper Publisher: John Wiley & Sons ISBN: 1118470850 Category : Medical Languages : en Pages : 2206
Book Description
Bovine Reproduction is a comprehensive, current reference providing information on all aspects of reproduction in the bull and cow. Offering fundamental knowledge on evaluating and restoring fertility in the bovine patient, the book also places information in the context of herd health where appropriate for a truly global view of bovine theriogenology. Printed in full color throughout, the book includes 83 chapters and more than 550 images, making it the most exhaustive reference available on this topic. Each section covers anatomy and physiology, breeding management, and reproductive surgery, as well as obstetrics and pregnancy wastage in the cow. Bovine Reproduction is a welcome resource for bovine practitioners, theriogenologists, and animal scientists, as well as veterinary students and residents with an interest in the cow.
Author: Harald Volden Publisher: Springer Science & Business Media ISBN: 9086867189 Category : Science Languages : en Pages : 172
Book Description
NorFor is a semi-mechanistic feed evaluation system for cattle, which is used by advisors in Denmark, Iceland, Norway and Sweden. This book describes in detail the system and it covers five main sections. The first is concerned with information on feed characteristics, feed analysis and feed digestion methods. The second section describes the digestion and metabolism in the gastrointestinal tract and the supply and requirement of energy and metabolizable amino acids. The third section considers the prediction of feed intake and physical structure of the diet. The fourth section focuses on model evaluation and the final section provides information on the IT solutions and feed ration formulation by a non-linear economical optimization procedure. This book will be of significant interest to researchers, students and advisors of cattle nutrition and feed evaluation.
Author: Michael J. Fields Publisher: CRC Press ISBN: 100015288X Category : Nature Languages : en Pages : 414
Book Description
Factors Affecting Calf Crop summarizes the latest information available from leading cattle physiologists and geneticists regarding factors known to influence the production of live calves at weaning. You get practical information on management techniques for improving reproduction efficiency in the herd. You'll also learn about the functioning of the reproductive system and how this may affect reproductive processes in the cow herd. Managers will benefit from a clearer understanding of the factors known to limit efficient reproduction, while veterinarians and other professionals who advise cattlemen will appreciate the substantial reference material and color photographs for defining cow condition scores. Color photographs are also used to illustrate the discussions of testicular thermographies and their applications. Other chapters in the book cover developments in improving reproductive performance of the replacement heifer, the brood cow, and the bull. Topics on reproduction include physiology/endocrinology, the use of growth promotants, genetics and physiological and economic considerations in selecting the age to breed heifers, heritability of fertility, length of the breeding season, prepartum and postpartum nutrition, nursing by the calf, cloning of embryos, and much more.
Author: Peter J. H. Ball Publisher: John Wiley & Sons ISBN: 1405148012 Category : Medical Languages : en Pages : 248
Book Description
Cattle play a fundamental role in animal agriculture throughout the world. They not only provide us with a vital food source, but they also provide us with fertilizer and fuel. Keeping reproduction levels at an optimum level is therefore essential, but this is often a complicated process, especially with modern, high yielding cows. Written in a practical and user-friendly style, this book aims to help the reader understand cattle reproduction by explaining the underlying physiology of the reproductive process and the role and importance of pharmacology and technology, and showing how management techniques can improve reproductive efficiency. This edition includes: Recent research findings on the physiology of the oestrous cycle and its control; New techniques for monitoring and manipulating reproduction, including pregnancy diagnosis and embryo transfer; Advice on identifying common infertility problems and how to prevent and treat them. Reproduction Cattle 3e is essential reading for veterinary and agricultural students, as well as veterinarians and farmers involved in cattle reproduction.
Author: Amanda Jillian Cain
Author: Amanda Jillian Cain
Author: Ricardo P. Arias
Author: Eilidh Thomson
Author: Katylyn Jo Richardson
Author: Alicia Caitlin Lansford
Author: Philip C. Garnsworthy
Author: Richard M. Hopper
Author: Harald Volden
Author: Michael J. Fields
Author: Peter J. H. Ball