This thesis aimed to evaluate different visual and radio frequency identification (RFID) devices for goats. As current European regulations lay down the official use of visual and RFID ear tags, rumen boluses, and marks on the pastern (injects and RFID leg bands), these devices were tested in 4 experiments. In Exp. 1, application and long-term readability of visual ear tags (V1: tip-tag; V2: official), mini-boluses (B1: 13.8 g; and B2: 20.0 g), RFID ear tags (E1: flag-button; E2: double button), and injects on the fore-hind pastern (T1: 15 mm; T2: 12 mm) in replacement Murciano-Granadina dairy goat kids (n = 97) were tested; standard-sized boluses (B3: 75 g) were evaluated as control devices in their mothers (n = 29). At 1 yr of age, readability of B3, E1 and E2 was 100%. Lower readabilities corresponded to B1 (71.4%) and V1 (82.9%). At 3 yr of age, only E1 was 100% readable. In conclusion, button RFID ear tags offered the best results for dairy goat ID at early ages. In Exp. 2, a total of 295 adult and yearling goats from Alpine, Angora, Boer, and Spanish breeds managed under semi-extensive conditions, were used. Management system and breed effects on the retention of 3 bolus types (B1: 20 g, n = 95; B2: 75 g, n = 100; and B3: 82 g, n = 100) and 1 visual ear tag were investigated. No early losses (1 mo) occurred, although ruminal pH varied by breed and feeding management (6.32 to 6.73). At 1 yr, bolus retention (98.1%) was greater than ear tag (91.7%). Lowest bolus retention was for B1 (96.3%), whereas it was 97.8% for B3, and 100% for B2. Ear tag retention varied between breeds (82.9 to 98.6%). In conclusion, standard-sized boluses offered suitable long-term retention for goats under semi-extensive conditions. In Exp. 3, adult Murciano-Granadina goats (n = 220) were identified with visual ear tags (VE), rumen boluses (RB: 75 g), RFID ear tags (EE, n = 47), and leg tags (LT) with 2 types of button transponders (ET1, n = 90; ET2, n = 130). According to shank circumference, LT for kid ID was discarded and only adult does were used. At 1 yr, no losses of LT occurred, although 1.5% were removed due to limping; readability of RB, EE, VE, ET1, and ET2 was 96.5, 95.7, 97, 93.9, and 98.3%, respectively. In conclusion, adequately designed leg tags are a valid ID method for adult dairy goats. In Exp. 4, 2,482 RFID rumen boluses from 19 bolus types were used to construct a regression model of bolus retention in goats. Bolus features varied in length (37 to 84 mm), o.d. (9 to 22 mm), weight (W, 5 to 111 g), volume (V, 2.5 to 26 mL), and specific gravity (SG, 1 to 5.5). A logit regression model with W and V as covariates was constructed (R2 = 0.98). Estimated W and SG to produce mini- (5 mL), medium- (15 mL) and standard-sized (22 mL) boluses for a retention rate of 99.95% were 42.9, 73.0, and 94.1 g, and 8.58, 4.87, and 4.28, respectively. Increasing bolus W and SG allowed V to be reduced. Suitable medium-sized boluses for goats can be produced with radio translucent materials currently available. In conclusion, under our conditions, visual ear tags and injects in the pastern were not recommended for official ID. Button electronic ear tags showed variable results according to type, and electronic leg tags were a valid method only for adult goats. According to the bolus retention model obtained, medium-sized boluses may be effectively produced for goat ID, but mini boluses are not recommended.
| Date of Award | 20 Jun 2010 |
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| Original language | Undefined/Unknown |
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| Supervisor | Gerardo Caja Lopez (Director) |
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