Exigências nutricionais de vacas nelores primíparas lactantes

Abstract

Nutritional requirements of primiparous lactating Nellore cowsABSTRACT -This study was conducted to evaluate the nutritional requirements of protein and energy of primiparous lactating Nellore cows from 0 to 180 days after calving. A total of 20 lactating primiparous cows with average body weight at calving of 362±25 kg were used. Four cows were slaughtered soon after calving and were considered as reference group. From calving to 90 days post partum four cows were fed restricted at 1.5% of body weight (BW) in dry matter (DM) basis and 12 were fed ad libitum. At 90 days post partum eight cows were slaughtered (four from each feeding system). From 90 to 180 days, four cows were realocated for maintenance (1.8% BW in DM) and four remained in voluntary intake, and all were slaughtered at the end of the period. The contents of protein and energy were estimated by the equation Y = a. X b , in which X is the empty body weight (EBW), and a and b are the parameters of the allometric equation. Ratios obtained for empty body weight (EBW)/BW and empty body gain (EBWG)/BWG were 0.894 and 0.936, respectively. The net energy for maintenance (NE m ) were 97.84 kcal/EBW 0.75 and the metabolizable energy for maintenance (ME m ) were 140.17 kcal/EBW 0.75 . The efficiencies of energy use for maintenance and gain were 0.70 and 0.44, respectively. The content of protein and minerals, except calcium, decreased with the increase in BW while the energy increased. The milk of cows had average contents of 3.71, 3.88 and 4.74%, respectively, for crude protein, fat and lactose. The NE m requirement for lactating Nellore cows is 97.84 kcal/EBW 0,75 , while ME m is 140.17 kcal/EBW 0,75 and metabolizable protein requirement is 52.8 g. To produce 1 kg of milk with 4% fat Nellore cows need 0.300 kg TDN.

Body mass index at calving on performance and efficiency of Zebu cow herds

“…their breed (Rodrigues et al, 2014), age (Castilho et al, 2018) and, mainly, nutritional level and its interaction with their body reserves (Moura et al, 2014), which makes it difficult to discuss these results. Fonseca et al (2012) also experimented with Nellore cows and described mean values close yet numerically higher than those found in the present study (3.71% protein, 3.88% fat, 4.74% lactose and 13.43% total solids). Nonetheless, these authors worked with a 180-day lactation period, which may have caused the qualitative components of milk to concentrate, whereas in this study we only evaluated the peak milk production period.…”

“…Daily and total milk yields differed between the BMI classes, with the small cows having lower daily and total values than the moderate and large cows. Smaller cows produce less milk due to their smaller size and lower synthesis efficiency (Fonseca et al, 2012), which results in lighter calves at weaning (Dervishi et al, 2017;Vara et al, 2020). However, pre-and postpartum nutrition (Lemes et al, 2017;Marques et al, 2016) and the calving season (Bitencourt et al, 2020) can influence the amount of milk produced.…”

Nutrient Requirements of Zebu and Crossbred Cattle - BR-CORTE

“…Also, ADG can be converted to empty body gain (EBG) by the ratio EBG/ADG equal to 0.958 for suckling calves (Fonseca et al, 2012b). Due to the lack of adjustment of data from the study of Fonseca et al (2012b), the requirements of ME for the maintenance of suckling calves was not estimated in the last edition of the BR-CORTE; however, Costa e Silva et al (2015b) (Fonseca et al, 2012b) To convert the net energy required for growth (NEg) to the metabolizable energy required for growth (MEg), two factors of efficiency of the use of MEg were utilized, with kg = 0.69 for milk intake and kg = 0.57 for solid feedstuffs intake according to the recommendations of the NRC (2001).…”

“…Also, ADG can be converted to empty body gain (EBG) by the ratio EBG/ADG equal to 0.958 for suckling calves (Fonseca et al, 2012b). Due to the lack of adjustment of data from the study of Fonseca et al (2012b), the requirements of ME for the maintenance of suckling calves was not estimated in the last edition of the BR-CORTE; however, Costa e Silva et al (2015b) (Fonseca et al, 2012b) To convert the net energy required for growth (NEg) to the metabolizable energy required for growth (MEg), two factors of efficiency of the use of MEg were utilized, with kg = 0.69 for milk intake and kg = 0.57 for solid feedstuffs intake according to the recommendations of the NRC (2001). Then, in the period from 0 to 90 days of age, the kg of 0.66 was considered (77 × 0.69 + 23 × 0.57) corresponding to the body weight of the animals weighing up to 100 kg; in the period from 90 to 180 days (> 100 kg body weight), the kg of 0.62 was considered (43 × 0.69 + 57 × 0.57), with 77 and 23%, and 43 and 57% being the relationships between milk intake and solid feedstuffs consumed by calves in the respective periods (Fonseca, 2009).…”

Exigências Nutricionais de Zebuínos Puros e Cruzados - BR-CORTE

“…Assim, dividindo ELm por EMm, a eficiência de utilização da energia metabolizável para mantença foi de 59,3%. As exigências de energia líquida para ganho (ELg) de bezerros Nelore lactentes (Fonseca et al, 2012b) foram estimadas pela seguinte equação: ELg = 0,0932 × PCVZ 0,75 × GPCVZ 0,9157 , em que ELg = exigência líquida de energia para ganho (Mcal/dia), PCVZ 0,75 = peso de corpo vazio metabólico e GPCVZ = ganho de peso de corpo vazio.…”