Master of Agribusiness / Department of Agricultural Economics / Dustin L. Pendell / Sachse Family Angus is both a commercial and registered Angus cow-calf operation in Northeast Kansas and has been in operation since 1935. The end goal in mind is to provide quality female breeding seedstock to other beef producers with the hopes of improving their herds. Successful selection and development of beef replacement heifers have major long term effects on stayability in any herd and can even have a positive impact on the whole herd. The objective of this study is to create a decision tool to determine best heifer selection strategies. Specifically, taking a look at the cost of heifer development under a range of scenarios as it applies to more traditional heifer development. The depth of literature addressing the issue of buying or raising replacement heifers is vast, providing various degrees of analysis to help a producer make the best informed decision. Some economists would argue that no single aspect of beef production management is as complicated, or has such an economic impact as cow culling and replacement heifer decisions (Melton, 1980). Procedures and methods were created to analyze whether a producer should raise or develop their own replacement heifers. One method used in creating a decision tool is an enterprise budget. Enterprise budgeting is the systematic determination and listing of expected outputs, revenues, and costs due to the production processes required to produce one unit of an enterprise for a specified time period. To take this one step further, it is assumed a producer makes choices with respect to the combinations of productive factors and products. Partial budgets include an analysis of net returns from small changes or refinement to a ranch. It focuses on parts that change while building upon an enterprise budget. In essence, it fine tunes current operations while holding all else constant. The benefits of partial budgeting take a look at what will be the new or added revenue if a change is implemented on the ranch and what costs will be reduced or eliminated if taken place. What will be the new or added costs and what revenues will be reduced if a change takes place are also things to keep in mind. Therefore, the result will show a producer the net benefit of the change. In turn, Sachse Family Angus will use this information to build their registered and commercial replacement heifers either by developing their own or purchasing from other breeders. Overtime, this decision will be critical as it will impact their herd for years to come. In conclusion, maintaining a good sound, high functioning beef cow herd means selecting and developing quality replacement heifers to retain in the herd each year. An estimated 20% of heifers born each year at Sachse Family Angus are kept as replacement heifers. When managing home raised heifers or purchased heifers, maintaining costs and keeping them in check is crucial because they represent a large up-front investment. The bottom line of this research is to give the managers at Sachse Family Angus and other operations across the country a decision tool that can be used to analyze their current resources and the resources it will take to develop their own heifers successfully and in the most cost effective way or help them analyze if purchasing their heifers makes the most financial sense.

Made available in DSpace on 2017-07-10T17:48:00Z (GMT). No. of bitstreams: 1 Suzana_da_Cruz_Pires.pdf: 722037 bytes, checksum: 952fb3e207015f4fad1448e7023d7836 (MD5) Previous issue date: 2014-03-18 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The heifers breeding for replacement of dairy herds have great importance for the national livestock. This breeding phase is critical and challenging due to numerous factors, but mainly when it comes to feeding management. The aim of this work was to evaluate the effect of three different volumes of milk replacer, provided for Holstein heifers up to 60 days, on the zootechnical performance and the relation cost-benefit of production. The work was carried out at the heifers Rearing Unit of Cooperativa Agroindustrial Lar in São Miguel do Iguaçu - PR. 45 heifers were used, randomly allocated into three treatments. With the use of an automatic feeder, the treatments were based on offering three different amounts of milk replacer: 4L Treatment (four liters); 6L (six liters) and AL (ad libitum). All animals received concentrate ad libitum. The morphometric measurements (height, body length, chest girth) and weight were measured weekly. The used experimental outline was completely randomized. It was performed the variance analysis and for comparison of means it was used Tukey at 5% significance. Data were analyzed by statistical program Sisvar. 4L and 6L heifers had higher concentrate intake than AL heifers. The feeding cost of 4L and 6L heifers was 66.42 and 90% respectively lower compared to AL heifers. AL heifers showed higher weight averages and morphometric measurements than other treatments in most of weeks. Regardless of the milk replacer volume supplied, 4L heifers showed higher concentrate intake and lower production cost. The zootechnical performance was similar for all treatments at weaning / As criações de bezerras para a reposição de rebanhos leiteiros têm grande importância para a pecuária nacional. Essa fase da criação é crítica e desafiadora em função de inúmeros fatores, principalmente quando se trata do manejo alimentar. O objetivo desse trabalho foi avaliar o efeito de três diferentes volumes de sucedâneo de leite, fornecidos para bezerras da raça Holandesa até 60 dias, sobre o desempenho zootécnico e a relação custo benefício de produção. O trabalho foi realizado na Unidade de Recria de Novilhas da Cooperativa Agroindustrial Lar no município de São Miguel do Iguaçu PR. Foram utilizadas 45 bezerras distribuídas ao acaso em três tratamentos. Com o uso de um alimentador automático, os tratamentos basearam-se na oferta de três diferentes quantidades de sucedâneo de leite: Tratamento 4L (quatro litros); 6L (seis litros) e AL (ad libitum). Todos os animais receberam concentrado a vontade. As medidas morfométricas (altura, comprimento corporal, perímetro torácico) e o peso foram mensurados semanalmente. O delineamento experimental utilizado foi o inteiramente casualizado. Foi realizada análise de variância e para comparação de médias foi utilizado Tukey a 5% de significância. Os dados foram analisados pelo programa estatístico Sisvar. As bezerras 4L e 6L tiveram consumo de concentrado superior às bezerras AL. O custo da alimentação das bezerras 4L e 6L foi de 66,42 e 90% respectivamente inferior em relação às bezerras AL. As bezerras AL apresentaram médias de peso e medidas morfométricas superiores aos demais tratamentos na maioria das semanas. Independente do volume de sucedâneo de leite fornecido, as bezerras 4L apresentaram maior consumo de concentrado e menor custo de produção. O desempenho zootécnico foi semelhante para todos os tratamentos ao desmame

<p dir="ltr">Nulliparous replacement beef heifers represent an opportunity to improve both genetic potential and lifetime production within the herd. However, advances in reproductive efficiency and synchrony in the herd require heifers to conceive earlier than multiparous cows in order to account for the extended postpartum interval following first-time parturition. Further, those heifers that achieve early calving dates continue to calve early throughout their lifetime. This early calving results in increased weaning weights and better synchrony in subsequent years. One obstacle producers face when breeding nulliparous heifers is the ability to identify which animals have reached puberty at the initiation of the breeding season. This results in the variation observed in synchronization success within a group of heifers. In Chapter 2 our laboratory formulated a study to analyze the efficacy of the 7-d CO-synch + CIDR protocol when utilizing short-term exposure to a progestin (melengestrol acetate, MGA) as a pre-synchronization protocol. Our hypothesis was that the heifers may respond more efficiently to an orally fed progestin as the increase in serum progesterone is less pronounced, when compared to the CIDR. This first study resulted in a protocol application error, in which MGA was fed an extra day (8 vs. 7). This additional day of treatment with MGA following the administration of a prostaglandin eliminated our laboratory’s opportunity to collect meaningful data from this first attempt. Thus, it was pertinent to restart the experiment in an attempt to obtain data for analysis. In order to avoid confounding data, half of the heifers in each treatment received a new treatment, while the other half remained on the treatment assigned during the first attempt. After completing the second round of experiments it was observed that at the first pregnancy check (study day 30), the heifers that were originally assigned to MGA, but were switched to a CIDR for the second attempt numerically outperformed their counterparts in the other three formulated treatment groups. In an attempt to replicate these results, a second study was formulated (Chapter 3), to mimic the timeline from the preliminary study. This resulted in a pre-synchronization treatment protocol prior to the initiation of the breeding season synchronization protocol. Previous studies that have been conducted with similar protocols were designed to provide heifers with a pre-synchronization period that would aid in the attainment of puberty prior to their first attempt at breeding through exposure to progesterone. The purpose of the Chapter 3 experiment was to evaluate the effects of feeding melengestrol acetate (MGA®) as a pre-synchronization for 10 days immediately prior to estrous synchronization and fixed-timed artificial insemination (FTAI). The ten days were chosen as this was a novel protocol that was the result of the preliminary study and the subsequent restart. Ninety-three crossbred heifers (395.67 ± 5.37 kg) were blocked by BW, genetics, and reproductive tract scores and allotted to 3 treatments. The 3 treatment groups were: 7-day CO-synch + CIDR without pre-synchronization (CON, n=31); 25 mg PGF2α (Lutalyse®) followed immediately by MGA feeding for 7 d prior to the start of the 7-day CO-synch + CIDR program (PRE, n=31); and 25 mg PGF2α followed immediately by MGA feeding for 7d followed 10 d later by the start of the 7-day CO-synch + CIDR program (PRE+10, n=31). The 7-day Co-synch + CIDR protocol in all three treatments was initiated on d 0 by administering a 2 cc IM injection of GnRH (Cystorelin®) and placing a CIDR into the vagina. The CIDRs were removed 7 days later and accompanied by 25 mg IM injection of PGF2α. An injection of GnRH occurred 60-66 hours following PGF2α at FTAI with frozen semen from a single bull. Ten days after FTAI, heifers were exposed to a bull. Estrotect® patches were applied throughout the study to assess estrous behavior. Ovaries were visualized by transrectal ultrasonography 24 hours post-FTAI to determine whether ovulation occurred. Pregnancy was determined on days 40, 64, and 109 post-FTAI via transrectal ultrasonography. Blood was collected via jugular venipuncture (d -19 and -12, MGA initiation and termination, days 0, 7, and 9) and serum progesterone determined. Performance data were analyzed using the MIXED procedure and conception data were analyzed using the GLIMMIX procedure of SAS. Heifers in the PRE+10 treatment group had higher levels of progesterone (P=0.04) at d 0 compared to PRE heifers. At d 7 (CIDR removal) there was a tendency (P=0.07) for PRE+10 heifers to have higher levels of progesterone than PRE, but did not differ by d 9 (FTAI, P=0.36). FTAI conception rates in heifers in the PRE treatment group (63%) tended (P = 0.09) to be higher compared to the controls (35%), but not different from PRE+10 (43%), with no differences in season-long pregnancy rates (P > 0.15). Pre-synchronization with MGA immediately prior to FTAI synchronization appears to increase conception rates early in the breeding season in beef heifers. In Chapter 4, our laboratory analyzed the efficacy of supplementation strategies post-insemination. Unlike the first two experiments, the third study focused on reproductive failure that occurs after insemination. The overarching goal remained the same, increasing the reproductive efficiency within our nulliparous heifer herd. A common practice for beef producers in the United States is to use estrous synchronization, and immediately turn heifers out to lush spring pasture immediately following FTAI. The fresh forage is high in water content which lowers dry matter intake (DMI) and creates a negative energy balance. Ultimately, this reduced energy intake can result in a reduction in reproductive performance. In the Chapter 4 our laboratory formulated a supplementation strategy utilizing the SmartFeed™ technology to deliver soybean hulls to our treatment group following insemination for 45 days. The utilization of the SmartFeed® technology provided the opportunity to analyze the efficacy of the supplementation strategy using each individual animal as an experimental unit. Sixty-two nulliparous crossbred heifers were fed in drylot to obtain moderate body condition prior to breeding at d 0 via FTAI and trained to utilize the SmartFeed™ system.Heifers were blocked by weight and body condition score to either the soybean hull supplementation group (SOY) or the non-supplemented control group (CON). . Heifers in the treatment group received their supplementation by entering the SmartFeed™ system, allowing for RFID controlled release of 2.27 kg. per head each day for 45 days. Scales located beneath each feed pan sent real time weight data for regulation and analysis on individual animal feeding behavior. On study d 6, a subset of the nulliparous crossbred heifers (n = 12; n = 6/ treatment) were transported by trailer from the Feldun Purdue Agricultural Center to Purdue West Lafayette main campus (approximately 217.74 km.). The subset of heifers had embryos flushed and evaluated for embryo quality and number of live/dead cells. Ultrasonography was utilized to monitor ovarian activity throughout the duration of the study and to determine pregnancy status 30 days after FTAI and 30 days after the 45-day breeding season. Though conception rates were not statistically (P=0.17) different (SOY 16/25; 64% vs. CON 11/25; 44%) when comparing treatment groups, the numerical differences suggest there is potential in pursuing a similar supplementation strategy following breeding in nulliparous beef heifers. The supplementation of SBH resulted in greater weight gain over time (P = 0.04), potentially explaining the numeric improvement in conception rate. The two pre-synchronization studies from Chapters 2 and 3 resulted in numerical improvements in conception rate as a result of exposing replacement heifers to a source of progestin prior to the initiation of their synchronization protocol. The implementation of progesterone priming mitigates the occurrence of short cycles and immature oocyte maturation at the time of ovulation. Based on results from previous studies conducted by our laboratory, the source of progestin greatly determines the timing and concentration of P4 circulating in replacement heifers immediately following treatment. Additionally, the 7 & 7 estrous synchronization protocol has grown in popularity and implementation. This protocol when broken down is very similar to the pre-synchronization protocol our laboratory utilized for the first two studies. Several studies have been conducted to analyze the efficacy of the 7 & 7 and the conception data was comparable to the MGA derived protocol. Thus, one potential direction for the future would be to formulate a research study that compares the two protocols. Since the conception rates were similar, it may be hypothesized that the MGA protocol could be more widely accepted as there is a reduction number of times animals are handled.</p>