Energy Requirements in Early Life Are Similar for Male and Female Goat Kids

Abstract

Little is known about the gender differences in energetic requirements of goats in early life. In this study, we determined the energy requirements for maintenance and gain in intact male, castrated male and female Saanen goat kids using the comparative slaughter technique and provide new data on their body composition and energy efficiency. To determine the energy requirements for maintenance, we studied 21 intact males, 15 castrated males and 18 females (5.0±0.1 kg initial body weight (BW) and 23±5 d of age) using a split-plot design with the following main factors: three genders (intact males, castrated males, and females) and three dry matter intake levels (ad libitum, 75% and 50% of ad libitum intake). A slaughter group included three kids, one for each nutritional plane, of each gender, and all three animals within a group were slaughtered when the ad libitum kid reached 15 kg in BW. Net energy requirements for gain were obtained for 17 intact males, eight castrated males and 15 females (5.1±0.4 kg BW and 23±13 d of age). Animals were fed ad libitum and slaughtered when they reached 5, 10, and 15 kg in BW. A digestion trial was performed with nine kids of each gender to determine digestible energy, metabolizable energy and energy metabolizability of the diet. Our results show no effect of gender on the energy requirements for maintenance and gain, and overall net energy for maintenance was 205.6 kJ/kg0.75 empty body weight gain (EBW) (170.3 kJ/kg0.75 BW) from 5 to 15 kg BW. Metabolizable energy for maintenance was calculated by iteration, assuming heat production equal to metabolizable energy intake at maintenance, and the result was 294.34 kJ/kg0.75 EBW and km of 0.70. As BW increased from 5 to 15 kg for all genders, the net energy required for gain increased from 9.5 to 12.0 kJ/g EBW gain (EWG), and assuming kg = 0.47, metabolizable energy for gain ranged from 20.2 to 25.5 kJ/g EWG. Our results indicate that it is not necessary to formulate diets with different energetic content for intact male, castrated male and female Saanen goat kids weighing from 5 to 15 kg.

Protein and energy requirements of castrated male Saanen goats

“…Although the knowledge of the partial efficiencies of the use of the ME for NE can improve our understanding of the energy partition for growing animals, few studies have reported a k g for goats (Bompadre et al, 2014;Fernandes et al, 2007;Tovar-Luna et al, 2007), whose value varied from 0.42 to 0.60. In this study, the k g was calculated as 0.39 (Eq.…”

“…This recommendation was based on studies using empirical models to assess the requirements by regressing intake of metabolizable energy or protein against response, such as body weight change (Sahlu et al, 2004). Because the nutritional requirements for gain are directly related to body composition, Lofgreen and Garrett (1968) proposed the comparative slaughter technique, which can address net requirements and is largely used to establish nutritional guidelines for cattle (NRC, 2000); however, few studies with goats have utilized this method (Fernandes et al, 2007;Bompadre et al, 2014).…”

Protein requirements for growth in male and female Saanen goats

“…In both trials, the experimental diet (Table 1) consisted of dehydrated whole corn plants (prepared as described by Bompadre et al, 2014), cracked corn grain, soybean meal, soybean oil, limestone, and a mineral supplement, which were fed as a total mixed ration at 46.2, 30.9, 15.2, 1.9, 1.0, and 4.8% of dry matter (DM), respectively. The feed ingredients were dried at 55 °C for 72 h, ground through a 1-mm screen using a Wiley mill (Arthur H. Thomas Co., Philadelphia, PA), and analyzed for ash ( To determine the NP m , 55 goats were used: 18 intact males (30.3±0.88 kg of body weight, BW), 21 castrated males (30.2±0.73 kg of initial BW), and 16 females (29.9±0.34 kg of initial BW).…”

Energy requirements and efficiency of energy utilization in growing dairy goats of different sexes

“…A data set that included reference, qualifying (e.g., sex, level of intake, and block), and necessary quantitative data were gathered from 7 comparative slaughter studies (Gomes, 2011;Bompadre et al, 2014;Medeiros et al, 2014;Almeida et al, 2015;Ferreira et al, 2015;Figueiredo et al, 2016Figueiredo et al, , 2017. Quantitative information included days on feed, initial and final BW, empty BW (EBW), DMI, metabolizable energy intake (MEI), and body composition for each individual animal.…”

“…Different feeding systems indicate that intact males require more ME M 273 than females (ARC, 1980;CSIRO, 1990;NRC, 2000NRC, , 2007. Conversely, individual studies conducted with goats have generally concluded that sex affects energy requirements for growth, but it does not affect energy requirements for maintenance (Ash and Norton, 1987;Bompadre et al, 2014;Almeida et al, 2015;Figueiredo et al, 2017). Therefore, contradictory results have been reported.…”