Efficacy of vaginal spaying and anabolic implants on growth and carcass characteristics in beef heifers.

Abstract

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.

Effects of ovariectomy and anabolic steroid implantation on the somatotrophic axis in feedlot heifers

“…Due to the lack of difference in DMI and the increased ADG in implanted heifers compared to control heifers, G:F was greater for implanted heifers at both d 28 (P = 0.03) and 42 (P = 0.01), but did not differ between d 28 and 42. This finding agrees with previous reports that indicate implantation improves feed efficiency (Adams et al, 1990;Garber et al, 1990).…”

“…Therefore, this lack of significance, in relation to gender, could have been due to the fact that implanted OVX heifers exhibited ADG similar to that of implanted intact heifers and was numerically greater than intact control heifers for the initial 28 d of the study (data not reported). This is in agreement with Garber et al (1990), as they found that OVX heifers exhibited a fourfold greater response to implantation than intact heifers. Also, Adams et al (1990) reported that implanting OVX heifers with Synovex-H resulted in BW gains similar to those in intact heifers implanted with Synovex-H.…”

“…Early research showed that ovariectomy decreased average daily gain (ADG) and gain : feed (G:F) (Ray et al, 1969), but more recent research has indicated that ovariectomy does not reduce ADG (Klindt & Crouse, 1990). Specifically, when implanted with either 20 mg estradiol benzoate and 200 mg testosterone propionate (Synovex-H) or 20 mg estradiol benzoate and 200 mg progesterone (Synovex-S), ovariectomized (OVX) heifers have exhibited a four-fold greater response in ADG to implantation than intact heifers (Garber et al, 1990); and when implanted with Synovex-H, OVX heifers had similar ADG to intact heifers implanted with Synovex-H (Adams et al, 1990). However, the physiological and molecular explanation for this performance recovery, via implantation is poorly understood.…”

Single-port laparoscopic ovariectomy using a pre-tied loop ligature in Santa Ines ewes

“…Other study also revealed no negative influence of laparoscopic ovariectomies on the physical condition of the ewes (TEIXEIRA et al, 2011). The castration of young females is indicated for a faster weight gain in cattle (GARBER et al, 1990). However, other studies found that flank laparotomy (CARVALHO et al, 2010) and transvaginal approach using latex ring for pedicle ligation in cows submitted to ovariectomy (MEIRELLES et al, 2007) caused negative influence concerning post-surgical weight gain.…”

“…Ovariectomy is not only performed to prevent pregnancy, but also to reduce problems related to the estrous cycle, such as interference on the weight gain (GARBER et al, 1990;BLEUL et al, 2005 …”