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A total of 60 twin-goat kids (30 male and 30 female) of the Canary Island Majorera dairy breed were used in 2 experiments to evaluate 2 types of electronic identification mini-boluses and their effects on rearing performances and reticulorumen development. Electronic identification mini-boluses were cylindrical and made of ceramic materials (Bi, 9.0 g and 38.5 x 9.5 mm; B2, 16.3 g and 42.2 x 12.2 mm), contained a 32-mm half-duplex passive transponder, and were administered to kids at different BW. In Exp. 1, treatments were 1) control, without bolus (n = 15) and 2) identified with Bi at 4.8 kg of BW (n = 15). In Exp. 2, treatments were 1) control, without bolus (n = 15) and 2) identified with B2 at 5.6 kg of BW (n = 15). Kids were penned separately, according to mini-bolus treatments, fed a milk replacer daily, and slaughtered at 10 kg of BW. Milk replacer intake was recorded individually twice weekly and boluses read weekly until slaughter. The full and empty stomach complex was measured immediately after slaughter, and mini-bolus location was recorded. Samples of the reticulum and rumen wall were taken to measure the number and length of the papillae and crest. Despite the light BW of kids at time of mini-bolus treatment, no negative effects (P > 0.05) of Bi and B2 mini-boluses were observed on milk intake, growth rate, or G:F in either experiment. No kid mortality or mini-bolus losses were observed during either experiment. All mini-boluses were retained until slaughter, and all were found in the rumen upon dissection, except one B2, which was found in the reticulum. Mini-bolus treatment did not affect (P > 0.05) the weight of full and empty reticulorumen or the number of papillae and crest size of the reticulum epithelium. Moreover, the Bi-treated kids showed a greater number of papillae in the rumen wall than the control kids (22.4 ± 1.0 vs. 18.9 ± 0.9 papillae/cm, respectively; P < 0.05) in Exp. 1. In conclusion, the use of mini-boluses was suitable for the electronic identification of growing kids from early ages (wk 2 to 5 of age and 5 to 6 kg of BW) and did not produce negative effects on their growth performances or on reticulorumen development. These results support the use of properly designed boluses as a unique identification device for the entire lifespan of goats. [ABSTRACT FROM AUTHOR]

Goats in Canary Islands are milked once a day, so they are adapted to accommodate large volumes of milk into their cisterns between milkings. Therefore it is important to know whether the oxytocin release by the stimulation of the mammary gland can increase the milk production when the goats are not milked immediately after the stimulation. Thirty-nine dairy goats in mid lactation (95±10 d in milk) were divided into 3 groups (n=13) on the basis of similar milk yields. During a period of 8-week, the goats from group 1 (OT1) were introduced to the milking parlor once a week, 10h after milking, and all pre-milking routines were carried out, including 2 to 3 stripping squirts of milk from each teat. However, the animals were not milked. During this period, the goats from group 2 (OT2) were injected intravenously with 2IU of oxytocin once a week, 10h after morning milking, while being placed in the crowd pen. However, the animals were not milked. The goats from group 3 (control) remained in the pen without any treatment. Milk recording and sampling were done the next day at the morning milking. Milk yield and milk composition in treatments OT1 and OT2 and control did not differ. The results suggest that oxytocin release by milking procedures or by administration of synthetically manufactured oxytocin did not reduce the content of milk in alveoli in dairy goats, which are not milked immediately. [ABSTRACT FROM AUTHOR]