Performance, rumen development, and metabolism of male Holstein calves (n=54) were evaluated according to 1 of 3 liquid feeding strategies: 4 L of milk replacer (MR)/d until 60 d old (4 L-60 d), 6L of MR/d until 29 d old and 4 L/d from 30 to 60 d (6L-29 d/4 L-60 d), or 6L of MR/day until 60 d old (60 d-6L). Water and starter were provided ad libitum. Intakes of MR and starter were monitored daily and body weight (BW) weekly. Blood samples for glucose and insulin concentrations and ruminal content samples for volatile fatty acids and ruminal ammonia concentrations were collected at 15, 30, 45, 60, 75, and 90 d of age. Six calves on each treatment were euthanized at 30, 60, and 90 d of age. Empty weights of forestomach and abomasum, papillae length, and mitotic index were measured. Average MR intake/d (expressed as a percent of BW) was greater for calves receiving 6L/d than for those receiving 4 L/d until 30 d of age. Calves on the 6 L-29 d/4 L-60 d had the smallest MR intake from 30 to 60 d old, followed by the 4 L-60 d and 6L-60 d treatments. Starter intake (kg of dry matter/day) did not differ between groups. It increased from 0.065 kg/d in the first month to 0.386 kg/d in the second month, and to 2.065 kg/d after weaning. Weight gain was greater for calves fed more MR in the first month, but no difference was observed during the second month. After weaning, 6L-60 d calves had greater rate of weight gain than others and were heavier at 30, 60, and 90 d of age. Weight of empty forestomachs, ruminal pH, and ammoniac nitrogen concentration were not different among groups. Propionate concentration was lower for 6 L-60 d calves, but acetate and butyrate concentrations were not influenced by MR feeding strategy. Calves fed more MR until d 30 had greater ruminal epithelium mitotic index. The different MR feeding strategies did not influence papillae length or ruminal epithelium thickness. Lesions such as ruminal parakeratosis or hyperkeratosis were not observed. The MR feeding strategy did not affect glucose concentration, but insulin was higher in 6L-60 d calves than in the other groups. Glucose concentration increased with age, whereas insulin decreased until 45 d old, and then started to increase until 90 d. In conclusion, MR feeding strategy did not influence ruminal development. Feeding calves 6 L of MR/d over 60 d resulted in greater rate of weight gain without negative effects on starter intake or forestomach development. The weight advantage that 6L-60 d calves obtained preweaning was maintained until 90 d of age.
The aims of this study were (1) to assess if there is phenotypical divergence for feed efficiency (FE) during the preweaning phase; (2) if FE is correlated with heat production (HP) measured by the face mask method or (3) by surface skin temperature via thermography, and (4) whether these methods are applicable to preweaned calves. Holstein × Gyr heifer calves (n = 36, birth body weight = 32.4 ± 6.6 kg) were enrolled and on trial between 4 and 12 wk of age and were classified into 2 residual feed intake (RFI) and residual body weight gain (RG) groups: high efficiency (HE; RFI, n = 10; and RG, n = 9) and low efficiency (LE; RFI, n = 10; and RG, n = 8). Calves were fed milk (6 L/d) and solid feed (95% starter and 5% chopped Tifton 85 hay, as fed). Growth was monitored weekly and feed intake (milk and solid feed) daily, during the whole period. Gas exchanges (O consumption and production of CO and CH) were obtained using a face mask at 45 ± 5 d of age and HP was estimated. Maximum temperatures were measured at 7 sites with an infrared camera at 62 ± 7 d of age. There was divergence in RFI and RG. Respectively, HE and LE calves had RFI of -0.14 and 0.13 kg/d, and RG of 0.05 and -0.07 kg/d. Dry matter intake was 15% lower in HE-RFI compared with LE-RFI, but no differences were observed in average daily weight gain. Within the RG test, no differences were observed in dry matter intake or average daily gain. The HE-RFI calves consumed less O (L/d) and produced less CO (L/d). Heart rate and HP were lower for HE-RFI calves compared with LE-RFI. Residual feed intake was correlated with HP (r = 0.48), O consumption (r = 0.48), CO production (r = 0.48), and heart rate (r = 0.40). No differences were observed in HP and gas exchanges between RG groups. Methane production was null in both groups. Eye temperature measured by thermography was 0.5°C greater in HE-RG than LE-RG calves. Differences in skin temperature between HE and LE calves were not observed at the other sites. These results support the hypothesis that calves are divergent for RFI, RG, and FE during preweaning and divergence tests are applicable during this phase. The face mask method described here is a useful tool for estimating differences in HP among phenotypically divergent RFI calves. Eye temperature measured by infrared thermography may have potential to screen phenotypically divergent RG calves.
O período de transição é um momento de grande desafio para vacas de aptidão leiteira, uma vez que, a maioria dos problemas metabólicos ocorre nesta fase podendo prejudicar toda a expectativa de produção durante a lactação, resultando em impacto econômico significativo para fazendas de produção de leite. Este trabalho teve como objetivo avaliar o perfil metabólico de vacas da raça Holandesa durante o período de transição. Doze vacas Holandesas foram avaliadas, três semanas pré-parto até três semanas pós-parto, em sistema free-stall, localizado em Inhaúma, Minas Gerais, no período de outubro a dezembro de 2012. Avaliou-se o perfil metabólico através da concentração sérica de ácidos graxos não esterificados (AGNE), beta hidroxibutirato (BHBA), colesterol (COLES), proteína total (PT), albumina (ALB), cálcio, fósforo, magnésio bem como a atividade sérica das enzimas aspartato transaminase (AST) e lactato desidrogenase (LDH). As concentrações séricas de AGNE e BHBA foram diferentes entre o pré-parto e pós-parto (p<0,05). Observou-se diminuição na concentração de COLES com a aproximação do parto com posterior aumento (p<0,05). As concentrações séricas dos minerais, PT e ALB não apresentaram diferenças (p>0,05) no período avaliado. A atividade enzimática de AST e LDH foram maiores no período pós-parto (p<0,05). A avaliação do perfil metabólico é uma importante ferramenta de monitoramento e, na situação estudada, demonstrou alterações do perfil energético das vacas entre os períodos pré e pós-parto, relacionadas provavelmente a diminuição da ingestão de alimentos. A luz dos resultados do perfil metabólico, o rebanho avaliado possui pequeno risco para a ocorrência de enfermidades no pós-parto relacionadas ao período de transição
RESUMO -Avaliou-se o desempenho produtivo de vacas da raça Holandesa mantidas em pastagem de coastcross (Cynodon dactylon (L.) Pears) fertilizada, irrigada e suplementada com 3 ou 6 kg de concentrado/vaca/dia. Dados de 108 lactações coletados durante três anos consecutivos (outubro/2000 a outubro/2003) foram analisados em um delineamento de blocos ao acaso com duas repetições por tratamento, utilizando-se nove animais por área e 18 por tratamento, com lotação fixa de cinco vacas/ha. Adotou-se o sistema de pastejo em lotação rotacionada, com um dia de ocupação e 25 e 35 dias de descanso dos piquetes, nas estações chuvosa e seca, respectivamente. A pastagem foi irrigada nos meses de menor precipitação e fertilizada com adubo formulado (NPK), distribuído a lanço em seis aplicações anuais. A disponibilidade de matéria seca foi de 7.280 e 6.167 kg/ha no início do pastejo, com resíduo pós-pastejo de 4.885 e 3.994 kg/ha, nas estações chuvosa (primavera/verão) e seca (outono/ inverno), respectivamente. Durante parte do período experimental, algumas características morfogênicas da pastagem foram avaliadas, registrando-se disponibilidade de 83,9; 125,6 e 89,5 kg de MS de lâminas foliares/ha, nas estações de primavera, verão e outono, respectivamente. As produções médias diárias de leite (corrigidas para 3,5% de gordura) foram de 15,5 e 19,1 kg/vaca e de 77,8 e 94,0 kg/ha, quando foram fornecidos, para cada vaca, 3 e 6 kg de concentrado, respectivamente. Pastagem de coastcross, quando fertilizada e manejada adequadamente, viabiliza elevadas produtividades de leite por animal e por área, podendo ser recomendada para produção de leite em pastagens.Palavras-chave: Cynodon, escore corporal, morfogênese, manejo, produção de leite Performance of Holsteins cows on coastcross pastureABSTRACT -The productive performance of Holstein cows grazing fertilized coastcross (Cynodon dactylon (L.) Pears) pasture, strategically irrigated and supplemented with either 3 or 6 kg of concentrate/cow/day, was evaluated in this trial. The data were collected for three years (October/2000 to October/2003), involving 108 lactations. A completely randomized block design with two treatment replications was adopted, with nine animals per paddock. The pasture was strip grazed at a stocking rate of five cows per hectare, with rest periods of 25 and 35 days in the rainy and dry seasons, respectively. The pasture was irrigated in the months of lowest rainfall and fertilized with NPK broadcast at six applications/year. The pre-grazing pasture masses were 7,280 kg/ha and 6,167 kg/ha with post-grazing residuals of 4,885 kg/ha and 3,994 kg/ha, in the rainy (Spring/Summer) and dry (Fall/Winter) seasons, respectively. During part of the experimental period, a few morphogenic characteristics of the pasture were evaluated. Leaf blade growth rates of 83.9, 125.6 and 89.5 kg DM/ha/day were recorded in the Spring, Summer and Fall season, respectively. The average daily milk yields were 15.5 and 19.1 kg/day/cow with 3.5% of fat and 77.80 and 94.00 kg/ha, for either 3 o...
RESUMO -Avaliaram-se as alterações bromatológicas e fermentativas de silagens de cana-de-açúcar com e sem milho desintegrado com palha e sabugo (MDPS) durante 100 dias de armazenamento. Foram determinados o pH, a capacidade tamponante e os teores matéria seca (MS), proteína bruta (PB), fibra em detergente neutro (FDN), hemicelulose e nitrogênio amoniacal em relação ao nitrogênio total (N-NH 3 /NT). Os dados foram analisados em delineamento experimental inteiramente casualizado, em esquema fatorial 2 × 21, com três repetições, no qual o fator A foi constituído pela cana picada in natura e cana picada com milho desintegrado com palha e sabugo e o fator B, pelos 21 tempos de armazenagem. Os resultados obtidos foram submetidos à análise de regressão. Os valores de pH decresceram nos cinco primeiros dias de 5,2 para 3,5 na silagem controle e de 5,2 para 3,6 naquelas com milho desintegrado com palha e sabugo. As silagens com milho desintegrado com palha e sabugo apresentaram pH superior aos das silagens controle, em média de 0,09 unidades. A inclusão de milho desintegrado com palha e sabugo ocasionou aumento dos valores de NH 3 /NT em todos os tempos. Na silagem controle, a redução do teor de MS foi de 14,1 unidades percentuais, enquanto naquelas com MDPS, foi IntroduçãoDiversas forrageiras, como o milho e o sorgo, têm potencial para ensilagem, porém é necessário o estudo de volumosos suplementares alternativos, não objetivando sua substituição, mas visando à sustentabilidade dos sistemas de produção.Entre as alternativas, tem-se a cana-de-açúcar, que possui, no entanto, elevado teor de açúcares na época da R. Bras.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.