Use of recombinant gonadotropin-releasing hormone antigens for immunosterilization of beef heifers.
The objectives of this study were to evaluate the effects of immunization against recombinant GnRH fusion proteins and growth promotants on onset of puberty, feedlot performance, and carcass characteristics of beef heifers. Heifers were immunized against an ovalbumin fusion protein containing 7 GnRH peptides (oGnRH, n = 12), a thioredoxin fusion protein containing 7 GnRH peptides (tGnRH, n = 12), a combination of oGnRH plus tGnRH (otGnRH, n = 12), or a combination of ovalbumin and thioredoxin (control, n = 11). Each heifer received a primary immunization containing 1 mg of protein in 1 mL of adjuvant injected into the mammary gland at wk 0 (mean age = 38 wk) and booster immunizations at wk 6 and 12. Six heifers within each treatment received Synovex H implants at wk -2. Weekly blood samples were collected from wk -2 to 26 for determination of serum progesterone concentrations and GnRH antibody titers. In GnRH-immunized heifers, GnRH antibody titers increased after the first booster injection, peaked after the second booster injection, and remained elevated through the end of the study (P < 0.01). Heifers immunized against oGnRH achieved greater (P < 0.05) GnRH antibody titers than tGnRH heifers but did not differ (P = 0.20) from otGnRH heifers. During the 26-wk study, ovulation was prevented (P < 0.05) in 10 out of 12, 12 out of 12, 11 out of 12, and 0 out of 11 tGnRH, oGnRH, otGnRH, and control heifers, respectively. At slaughter, uterine weights were lighter (P < 0.01) for GnRH-immunized heifers than control heifers. Synovex H-implanted heifers had greater (P < 0.05) ADG from wk -2 to 26, greater LM area, and lesser percentages of KPH, yield grade, and quality grade than nonimplanted heifers, regardless of the immunization treatment. Immunization against GnRH fusion proteins resulted in production of antibodies against GnRH that prevented ovulation in 92% of the heifers without affecting feedlot or carcass performance. Implanting heifers with Synovex H improved ADG, LM area, and yield grade. Improvements in delivery of the oGnRH vaccine may provide a feasible alternative to surgical spaying of heifers.
Efficacy of vaginal spaying and anabolic implants on growth and carcass characteristics in beef heifers.
Ninety crossbred beef heifers averaging 260 kg were blocked by weight and allotted randomly to 15 pens of six heifers each, with three replicates per treatment. The treatments were spayed heifers (S); intact heifers (I); S + Synovex-H7 (SH); I + Synovex-H (IH); and S + Synovex-S7 (SS). The heifers were spayed vaginally with a Willis instrument; intact heifers were rectally palpated for reproductive soundness. Heifers were fed a growing diet (55 d), re-implanted and subsequently fed a finishing ration (73 or 101 d). All heifers were observed for estrus daily at approximately 0600 and 2000 until d 69. A jugular vein blood sample was obtained from each heifer on d 48, 55, 62 and 69 for blood progesterone analysis. Results of blood progesterone analysis and reproductive tract examination indicated that two spayed heifers were incompletely spayed, a 96% success rate. The SH and SS heifers continued to exhibit estrous behavior despite being successfully spayed. Heifers implanted with Synovex-H had greater (P less than .01) ADG and were more efficient (P less than .03) than nonimplanted heifers. The SS heifers had greater ADG (P less than .05) during the finishing phase than SH heifers, but no advantage of SS over SH was apparent during the growing phase. The overall ADG response to implantation was fourfold greater (P less than .07) in the spayed heifers than in the intact heifers (32 vs 8%). Heifers implanted with Synovex-H had greater adjusted hot carcass weight (P less than .02) and ribeye area (P less than .002) than nonimplanted heifers. For adjusted live weight and ribeye area, the response to implantation was approximately threefold greater in the spayed heifer than the intact heifer. These results demonstrate that spaying and implanting heifers can increase rates and efficiency of gain even though behavioral estrus is not eliminated.
Product Literacy and the Economics of Consumer Protection Policy
I suffer from overoptimism bias. I know this, yet I accepted the invitation to write a commentary on product literacy and consumer protection for this special issue. After devoting over twenty-five years to consumer protection research and law enforcement at the Federal Trade Commission (FTC), the topic was in my wheelhouse. Surely, I could meet a deadline that seemed reasonably far away. But I also suffer from hyperbolic discounting, so I procrastinated. When I finally sat down in earnest to write this essay, panic set in, because I realized that the concept of product literacy is not well defined. Now what? Relying on my overoptimism, I decided to create my own definition. This exercise forced me to confront vexing questions about competing theories of consumer behavior and their implications for consumer policy. Consumer policy development depends fundamentally on the policy maker's view of consumer behavior. Policies will differ depending upon whether consumer decisions are viewed as rational, irrational, or somewhere in between. Yet, theories regarding rational consumer choice are in a state of flux, largely due to the growth and popularization of behavioral economics. Popular books such as Nudge have placed behavioral economics front and center in consumer policy circles (Thaler and Sunstein 2008). It is now fashionable inside the Washington DC Beltway to point to behavioral research suggesting that consumers do not maximize wealth, are overly optimistic, or procrastinate due to hyperbolic discounting, as proof that policies based on rational consumer models are insufficient to protect consumers (Kobayashi et al. 2012). This conclusion is then frequently used to argue that new policies should be implemented to protect people from their irrational selves. For example, some argue that mandating information disclosures from sellers is not enough--because consumers do not pay enough attention to them--and that disclosure regimes should be supplemented with or replaced by more prescriptive remedies, such as product bans or product preapproval mechanisms (Ben-Shahar and Schneider 2011; Posner and Weyl 2012). Although the future of consumer policy will be shaped by prevailing views of consumer rationality, there is surprisingly little serious debate among scholars from different disciplines or subdisciplines about the evidence for and against different models of consumer decision making. There are notable exceptions, but even when meaningful debate occurs it is often clouded by confusion over the precise meaning of key terms. What does it really mean for a consumer to be rational, or irrational, or reasonable? Discussion in behavioral circles tends to focus on whether people behave rationally, in the sense that people maximize an unconstrained or partially constrained utility problem. Evidence that people do not behave according to simple utility maximization models is often seen as evidence that people are not rational. What I find perplexing is why the standard for rationality in behavioral discussions tends to be based on utility maximization or wealth maximization constrained only by limited financial resources. I find this perplexing because the economics of consumer behavior, as taught in graduate school over thirty years ago, was based on a much more realistic model of consumer choice. When I explain this at conferences I encounter surprise by practitioners and scholars who are fluent in behavioral economics. Consumer economists have long understood that consumers face real time constraints, wealth constraints, and household production constraints, including decision-making and information-processing constraints. In this essay, I define product literacy and discuss where the concept fits within the law and economics of consumer protection. In so doing, I attempt to clarify what it means to be a rational consumer vs. a reasonable consumer vs. an irrational consumer. These different views of consumer behavior matter, because they can lead to different policies with different implications for consumer choice and consumer welfare. …