Diet density in rearing and reproductive phases influences carcass composition, pregnancy rate and litter performance of primiparous rabbit does

The objective was to evaluate the effect of the interaction of diet density in the rearing phasexdiet density in the reproductive phase on carcass composition, pregnancy rate, and litter performance of primiparous rabbit does. The experiment followed a 2x2x2 factorial (2 seasons, 2 diet densities in the rearing phase and 2 diet densities in reproductive phase, that is, from mating to weaning of the first litter). The reference diet (RD) contained 184 g/kg of crude protein (CP), 165 g/kg of acid detergent fibre (ADF) and 10.5 MJ/kg of digestible energy (DE). The low-density diet (LD) had 147 g/kg of CP, 24 g/kg of ADF and 8.4 MJ/kg of DE. The treatments were applied from 70 d of age until weaning of the first litter at 35 d of age. Ninety-six females from the Botucatu Genetic Group (24 females/experimental group) were mated at 142 d of age. On day 12 of gestation, 23 does were slaughtered to evaluate weights of carcass, organs and dissectible fat, and embryo implantation rate. No effects of diet density in the rearing or in the reproductive phases were detected on feed intake of does during the reproductive phase. Does fed LD during the rearing phase showed lower body weight at mating (3574 47 vs. 3866 43 g, P=0.0001) and during most of the reproductive phase, but they lost less weight in the peripartum. Perirenal fat was lighter in these does (72.8 +/- 10.0 vs. 102.1 +/- 9.6 g, P=0.048) and they showed a lower pregnancy rate (76.1 vs. 91.7%, P=0.045). The does fed RD in the reproductive phase were heavier during this phase (4055 +/- 40 g vs. 3887 +/- 41 g, P=0.0044). The does fed LD in rearing phase and RD in the reproductive phase showed larger litters at weaning, due to decreased kit mortality, than those fed RD in both phases (6.16 +/- 0.47 vs. 3.93 +/- 0.71, P=0.0361). Litters were lighter at weaning when LD was fed in the reproductive phase (3582 +/- 201 vs. 4733 +/- 187, P<0.0001). Feeding a low density diet during the rearing phase and a reference diet during the reproductive phase is the best alternative to improve reproductive performance at the first parity.

Comportamento alimentar de vacas Nelore e de seus bezerros puros ou mestiços / Feeding behavior of Nellore cows and their pure or crossbred calves

O objetivo desta pesquisa foi avaliar a influência do grupo genético do bezerro no comportamento alimentar diurno de mães e suas crias. Foram utilizadas 24 vacas Nelores paridas e seus bezerros, oito Nelores (puros), oito 1/2 Simental 1/2 Nelore e oito 1/2 Red Angus 1/2 Nelore. Avaliaram-se as medidas de frequência e duração das mamadas, tempo de pastejo e ruminação dos bezerros e das vacas. Os bezerros puros mamaram mais frequentemente que os mestiços (3,51 vs. 3,17 vezes/dia), porém com menor duração de mamada (7,37 vs. 7,80 minutos). A frequência de mamadas, a duração de cada mamada e o tempo total de mamadas diminuíram com o aumento da idade do bezerro. Nos bezerros, pastejo e ruminação aumentaram com a idade; entretanto, nas vacas, aumentou o tempo de pastejo e diminuiu o de ruminação com o passar dos dias. Os bezerros mestiços pastaram, em média, 18 minutos a mais que os puros, e os machos 16 minutos a mais que as fêmeas. Os bezerros machos ruminaram, aos 40 dias de idade, 25 minutos a mais que as fêmeas, mas essa diferença diminuiu com a idade e desapareceu por volta dos 220 dias. O comportamento da mãe e de sua cria é influenciado pelo grupo genético desta última.(AU)

The aim of this study was to evaluate the effect of a calf's genetic group on the behavior of dam and calf. We used 24 Nellore dams and their calves, of which eight were Nellore, eight were 1/2Simmental 1/2Nelore and eight 1/2Red Angus 1/2Nellore. Grazing and rumination times, as well as suckling frequency and time, were measured. The straight bred calves suckled more often than the crossbreds (3.51 vs. 3.17 times/day), but their suckling lasted less time (7.37 vs 7.80 minutes). Suckling frequency, suckling length and total time spent suckling decreased as calf age increased. Calf grazing and rumination time increased with age; however, the cows' grazing time increased and rumination time decreased as the days postpartum went by. The crossbred calves grazed, on average, 18 minutes longer than the crossbreds, and the males grazed 16 minutes longer than the females. The male calves grazed, at 40 days of age, 25 minutes longer than the females, but this difference decreased as they grew and disappeared around 220 days. In conclusion, dam and calf behavior are influenced by the calf's genetic group.(AU)

Reproductive performance and reconception of Nellore cows according to their pure- or cross-bred calves.

The objective of the present research was to evaluate the effect of a calf's genetic group on the productive and reproductive efficiency of its Nellore dam. Fixed-time artificial insemination was applied to 800 cows using semen extracted from Nellore, Simmental and Angus Red bulls. Four hundred eleven cows calved, producing 119 Nellore, 103 ½Simmental-½Nellore and 189 ½Nellore-½Angus Red calves. The second mating period, which paired Nellore cows with Simmental bulls, was initiated 10 days after parturitions began and lasted for 5 months. Based on the two successive parturitions, the cumulative parturition rate for calving periods of 3, 4 and 5 months was calculated. Although no significant difference was observed for birth weight among the genetic groups, cross-bred calves weighed, on average, 10% more than did pure-bred calves at the age of 205 days. Nellore dams experienced a gestation period that was 7 days longer than did the cross-bred dams, and the former showed a higher parturition rate at 90 and 120 days of the calving season, but not at 150 days (calving rates of 80.6, 76.4 and 76.2% for mothers of Nellore, ½Nellore-½Angus Red and ½Nellore-½Simmental, respectively, p > 0.05). At 90 and 120 days, Nellore dams produced more kg of calf per mated dam. In conclusion, in a short breeding season, Nellore dams nursing pure-bred Nellore calves were found to have a higher biological efficiency compared with Nellore dams nursing cross-bred calves.

Diurnal behavior of dairy cows on alfalfa pastures supplemented with corn silage and concentrate / Comportamento diurno de vacas leiteiras em pastagem de alfafa suplementada com silagem de milho e concentrado

The diurnal ingestive behavior of dairy cows on alfalfa pastures supplemented with corn silage and concentrate was evaluated. Sixteen Holstein dairy cows in mid-lactation were used in a randomized block design. The treatments were partial replacement of corn silage for limited alfalfa grazing time (LGT) or unlimited grazing time (UGT). Rotational alfalfa grazing was used and the amount of concentrate fed was the same in both treatments. Behavioral activities observed were time spent grazing, rumination and idleness, during four days, from 8:00 AM to 7:00 PM. From 2:00 to 5:00 PM grazing was intermittent and short-lasting on UGT, whereas on LGT grazing activity was longer than UGT in the morning and at the end of the afternoon. Restriction in available grazing time clearly influenced the distribution of time spent with grazing, rumination and idleness throughout the day. However, this effect was not observed in the total time spent in these activities...

Avaliou-se o comportamento ingestivo de vacas leiteiras com acesso restrito ou irrestrito a uma pastagem de alfafa suplementada com silagem de milho e concentrado. Utilizaram-se 16 vacas da raça Holandesa, em estádio médio de lactação, em delineamento em blocos ao acaso. Os tratamentos foram: silagem de milho substituída parcialmente por pastejo restrito ou irrestrito de alfafa. As vacas foram manejadas em sistema de pastejo rotacionado e a quantidade de concentrado foi igual em ambos os tratamentos. As atividades comportamentais observadas foram pastejo, ruminação e ócio, das oito às 19 horas, em quatro ocasiões. No pastejo irrestrito, observou-se que, nos horários entre 14 e 17 horas, o pastejo foi intermitente e de curta duração, enquanto no pastejo restrito a atividade de pastejo foi mais prolongada durante a manhã e no final da tarde. A restrição no tempo disponível para pastejo da alfafa influenciou marcadamente a distribuição, no decorrer do dia, do tempo gasto em pastejo, da ruminação e do ócio. Entretanto, não se observou este efeito no tempo total gasto nestas atividades...

Desempenho e características da carcaça de bovinos alimentados com dietas com caroço de algodão / Performance and carcass traits of steers fed diets containing whole cottonseed

Avaliou-se o efeito da adição de caroço de algodão à dieta de bovinos confinados sobre o desempenho animal e características da carcaça. Usaram-se 36 novilhos Nelore com médias de idade e peso vivo inicial de 20 meses e 333,5kg. Os animais foram confinados e receberam dietas com os seguintes teores de caroço de algodão: 0; 14,35 por cento; 27,51 por cento; e 34,09 por cento na matéria seca da dieta. O ganho de peso diário, peso vivo final e consumo de matéria seca diminuíram linearmente com o aumento da proporção de caroço de algodão na dieta. Não foi observado efeito sobre o ganho de peso total ajustado ao consumo. Os pesos da carcaça e do contrafilé diminuíram linearmente com o aumento da proporção de caroço de algodão na dieta. Não foi observado efeito do teor de caroço de algodão sobre a área de olho de lombo. A espessura de gordura de cobertura do dorso e da garupa diminuíram com o aumento do teor de caroço de algodão. Observou-se correlação de 0,62 entre as duas medidas de gordura. A adição de caroço de algodão à dieta de bovinos de corte não se mostrou vantajosa, pois diminuiu o desempenho animal e a deposição de gordura na carcaça.

The purpose of this experiment was to evaluate the effect of adding whole cottonseed to the diet of feedlot cattle over the performance and carcass traits. Thirty six Nellore bullocks were used, with an average age of 20 months and average initial weight of 333.5kg. The animals were raised on feedlot and fed diets with the following content of whole cottonseed: 0; 14.35 percent; 27.51 percent; or 34.09 percent on a dry matter basis. The daily weight gain, final weight and dry matter intake decreased linearly as the proportion of cottonseed increased. No effect of cottonseed on total weight gain adjusted for intake was observed. Carcass and ribeye weights decreased linearly as cottonseed content increased. No effect of cottonseed content was observed for ribeye area. In contrast, back fat and rump fat thickness decreased as cottonseed content increased. A correlation of .62 was observed between back fat and rump fat. Adding whole cottonseed to beef cattle diets did not prove advantageous because it reduced animal performance and carcass fat deposition.

Desempenho de vacas leiteiras em pastagem de alfafa suplementada com silagem de milho e concentrado e viabilidade econômica do sistema / Performance of dairy cows on alfalfa pasture supplemented with corn silage and concentrate and its economic viability

Avaliou-se o efeito da substituição parcial de silagem de milho por pastagem de alfafa no desempenho de vacas leiteiras e na viabilidade econômica do sistema. Utilizaram-se 24 vacas da raça Holandesa, em estádio médio de lactação, em delineamento em blocos ao acaso. Os tratamentos foram: dieta à base de silagem de milho em confinamento, silagem de milho substituída parcialmente por pastejo restrito (PR) e pastejo irrestrito (PI) de alfafa. O sistema de pastejo foi rotacionado, e a quantidade de concentrado igual em todos os tratamentos. A massa de forragem foi de 2.338 e de 1.878kg de MS/ha, e a oferta de 1,8 e 4,2kg de MS/100kg de peso vivo, nos tratamentos PR e PI, respectivamente. A produção de leite não diferiu entre os tratamentos, cujas médias foram de 25,9; 25,8 e 25,2 litros por vaca por dia no confinamento, no PR e no PI, respectivamente. A produção diária de leite por área foi de 59,3L/ha no PR e de 63,0L/ha no PI, enquanto no confinamento foi de 45,7L/ha. A substituição parcial de silagem de milho por alfafa em pastejo não limitou o desempenho produtivo dos animais e mostrou-se economicamente vantajosa em relação ao confinamento.

The effect of partial replacement of corn silage for alfafa grazing on dairy cows performance and profitability was evaluated. Twenty-four Holstein dairy cows in mid-lactation were used in a randomized block design. Treatments were: a corn silage-based diet fed on drylot, or partial replacement of corn silage for either restricted alfalfa grazing or unrestricted grazing. A rotational grazing system was used and the amount of concentrate fed was the same in all treatments. Forage availabilities were 2,338 and 1,878kg/ha of dry matter (DM) and offered at 1.8 and 4.2kg of DM/100kg of live weight under restricted and unrestricted grazing, respectively. No difference in milk production was observed among treatments, averaging 25.9, 25.8, and 25.2 liters per cow on feedlot, restricted grazing, or unrestricted grazing, respectively. Milk production per hectare was 59.3L/day on restricted grazing and 63L/day on unrestricted grazing, whereas it was 45.7L/day on drylot. Partial replacement of corn silage for alfalfa grazing did not limit animal performance and it would be economically advantageous as compared to drylot feeding.

Progesterone concentrations, exogenous equine chorionic gonadotropin, and timing of prostaglandin F(2alpha) treatment affect fertility in postpuberal Nelore heifers.

Two experiments were performed to test the hypothesis that elevated progesterone concentrations impair pregnancy rate to timed artificial insemination (TAI) in postpuberal Nelore heifers. In Experiment 1, postpuberal Nelore heifers (n=398) received 2mg estradiol benzoate (EB) and either a new progesterone-releasing intravaginal device containing 1.9g of progesterone (CIDR) (first use) or a CIDR previously used for 9 d (second use) or for 18 d (third use) on Day 0, 12.5mg prostaglandin F(2alpha) (PGF(2alpha)) on Day 7, 0.5mg estradiol cypionate (ECP) and CIDR withdrawal on Day 9, and TAI on Day 11. Largest ovarian follicle diameter was determined on Day 11. The third-use CIDR treatment increased largest ovarian follicle diameter and pregnancy rate. Conception to TAI was reduced in heifers with smaller follicles in the first- and second-use CIDR treatments, but not in the third-use CIDR treatment. In Experiment 2, postpuberal Nelore heifers received the synchronization treatment described in Experiment 1 or received 12.5mg PGF(2alpha) on Day 9 rather than Day 7. In addition, 50% of heifers received 300 IU equine chorionic gonadotropin (eCG) on Day 9. Heifers were either TAI (Experiment 2a; n=199) or AI after detection of estrus (Experiment 2b; n=125 of 202). In Experiment 2a, treatment with eCG increased pregnancy rate to TAI in heifers that received PGF(2alpha) on Day 9 but not on Day 7 and in heifers that received a first-use CIDR but not in heifers that received a third-use CIDR. Treatments did not influence reproductive performance in Experiment 2b. In summary, pregnancy rate to TAI in postpuberal Nelore heifers was optimized when lower concentrations of exogenous progesterone were administered, and eCG treatment was beneficial in heifers expected to have greater progesterone concentrations.

Age-related changes in muscle fiber type frequencies and cross-sectional areas in straightbred and crossbred rabbits.

This study was designed to investigate the effects of the interaction among genetic group, sex and age on the frequencies and cross-sectional areas of myofiber types in rabbits. A total of 48 straightbred and crossbred Botucatu rabbits, males and females, were involved in a split plot design with a 2 × 2 (genetic groups × genders) factorial arrangement. Young rabbits were weaned at 35 days of age and sequentially slaughtered, four per genetic group × sex combination, at 42, 63 and 84 days of age. The flexor carpi radialis muscle was dissected, histological sections (10 µm) were obtained and the frequencies and cross-sectional areas of myofiber types: I, IIA and IIB/X were determined. An effect of the genetic group × sex × slaughter age interaction was found on the frequency distribution of myofiber types. A transition from type IIA to type IIB/X fibers was observed (P < 0.01) with advancing age, except in crossbred females, but the frequency of IIA fibers was already lower (57.3%) and of IIB/X fibers numerically higher (33.7%) in this group at 42 days. The proportions of IIA fibers in straightbred males, crossbred males and straightbred females decreased from 80.1%, 89.4% and 68.8% at 42 days to 43.9%, 52.3% and 40.1% at 63 days, respectively, whereas the proportions of type IIB/X fibers, in the same groups, increased from 10.3%, 1.6% and 22.3% at 42 days to 42.2%, 37.0% and 49.8% at 63 days, respectively. In all three age points, type IIA fibers showed the largest cross-sectional areas, followed by type I and IIB/X fibers. The cross-sectional areas of IIB/X fibers were larger in crossbreds, but no differences were found between genetic groups concerning fiber types IIA and I. All three types of fibers showed positive linear association with age, but relative to the initial area type IIB/X fibers presented a higher degree of hypertrophy (144% up to 84 days) than type IIA and I fibers (86% and 85%, respectively). The flexor carpi radialis muscle was, on average, heavier in crossbred than in straightbred females, but no difference was observed between crossbred and straightbred males. Differences in the weight of flexor carpi radialis muscle were attributed to the hypertrophy of type IIB/X fibers in the crossbreds.

Avaliação nutricional da silagem de grãos úmidos de milho com diferentes teores de óleo para leitões na fase de creche / Nutritional evaluation of high moisture corn silage with different oil contents for piglets in nursery phase

Utilizaram-se 60 leitões mestiços (Large White x Landrace), desmamados com peso inicial médio de 7,9kg, no experimento de desempenho e 20 leitões mestiços, com peso inicial médio de 16,8kg, no experimento de digestibilidade para avaliar a silagem de grãos úmidos de milho com diferentes teores de óleo. O delineamento experimental foi o de blocos ao acaso em ambos os experimentos avaliou-se o valor nutricional das silagens e dos milhos secos com teor normal (4,3 por centoEE na MS) ou elevado de óleo (5,66 por centoEE na MS). Não houve efeito dos tratamentos sobre o consumo diário de ração e no ganho de peso diário nos períodos de 0 a 9 e 0 a 31 dias. Os leitões apresentaram melhor conversão alimentar em ambos os períodos estudados, quando receberam silagem e no período de 0 a 9 dias, quando foram alimentados com milho com teor mais alto de óleo. As frações digestível e metabolizável da energia foram influenciadas pelo processamento, sendo que a ensilagem proporcionou melhor aproveitamento da energia, independentemente do teor de óleo presente nos grãos.

Sixty crossbred weaned pigs (Large White x Landrace) average initial body weight of 7.9kg and 20 crossbred pigs average initial body weight of 16.8kg were used in the performance and digestibility experiments, respectively, to evaluate high-moisture corn silage with different oil contents. The nutritional value of high-moisture corn silage and dry corn with normal (4.3 percent EE in DM) or higher (5.66 percent EE in DM) oil contents were analyzed. The treatments had no effect on either average daily feed intake (ADFI) or average daily gain (ADG) from 0 to 9 and 0 to 31 days. The piglets had higher feed/weight gain in both periods when fed silage and in the period from 0 to 9 days when fed higher oil content corn. In the digestibility experiment only the digestible and metabolizable fractions of energy were affected by the processing method and the silage provided higher energy utilization regardless of the oil content in the grains.

Valor nutricional da silagem de grãos úmidos de milho com diferentes graus de moagem para leitões na fase de creche / Nutritional value of high moisture corn silage with differents particle sizes for piglets in nursery phase

Utilizaram-se 72 leitões mestiços (Landrace x Large White), com peso inicial médio de 7,1kg, no experimento de desempenho e 20 leitões mestiços, com peso inicial médio de 18,9kg, no experimento de digestibilidade para avaliar a silagem de grãos úmidos de milho com diferentes granulometrias para leitões em fase de creche. O delineamento experimental foi em blocos ao acaso. Em ambos os experimentos avaliaram-se o valor nutricional das silagens com diâmetro geométrico médio (DGM) das partículas de 979, 1168 e 2186æm e do milho seco com DGM das partículas de 594æm. Na fase de zero ao oitavo dia, a silagem proporcionou menor consumo diário de ração (CDR) em relação ao milho seco, e foi verificado aumento linear no CDR com o aumento da granulometria da silagem. A silagem com granulometria média e grossa proporcionou melhora na conversão alimentar (CA) em relação ao milho seco, mas não foi observada diferença no ganho diário de peso (GDP). Para o período total, não foram observadas diferenças estatísticas para CDR e GDP, entretanto a silagem proporcionou melhora na CA em relação ao milho seco havendo efeito linear crescente da granulometria da silagem sobre a CA. A granulometria da silagem não influenciou nos coeficientes de digestibilidade aparente (CDA) da matéria seca e da proteína bruta, porém proporcionou maiores CDA do fósforo e valores de energia digestível em relação ao milho seco. O CDA do cálcio e os valores de energia metabolizável foram maiores para a silagem com granulometria fina e média, comparado ao do milho seco. Houve redução linear do CDA do cálcio com o aumento da granulometria da silagem.

Seventy-two crossbred pigs (Landrace x Large White) average initial body weight of 7.1kg and 20 crossbred pigs average initial body weight of 18.9kg were used in the performance and digestibility experiments to evaluate high-moisture corn silage with different particle sizes for piglets in nursery phase. A randomized block design was used. In both experiments the nutritional values of high-moisture corn silage with 979, 1168 and 2186æm geometric mean particle sizes (GM) and dry corn with 594æm GM were evaluated. From day 0 to 8, high-moisture corn silage provided daily feed intake (ADFI) lower than dry corn. A linear increase was observed to this variable when increasing the particle size of the silage. The silage with intermediate and coarse particle sizes provided higher feed/weight gain than the dry corn, but no difference in average daily gain (ADG) was observed. Throughout the experimental period, there were no statistical differences in ADFI and ADG. Therefore, the silage improved feed/weight gain in comparison to the dry corn. There was a linear increase of values of this variable as particle size of the silage increased. No effect of particle size of the silage on the apparent digestibility coefficients (ADC) of dry matter and crude protein was observed. However, it provided higher phosphorus ADC and values of digestible energy than the dry corn. Calcium ADC as well as values of metabolizable energy increased for silage with fine and intermediate particle sizes in comparison to the dry corn silage. Calcium ADC linearly decreased as the particle size of the silage increased.

Detecçäo de subfertilidade em vacas leiteiras por meio de medidas anatômicas da regiäo pélvica e do aparelho genital / Evaluation of subfertility in dairy cows by measuring the pelvis and the genital tract

O objetivo deste estudo foi mensurar as regiöes que compöem a garupa da vaca leiteira, com aparelho desenvolvido para esse fim, e avaliar o efeito dessas variáveis na contaminaçäo intra-uterina e na eficiência reprodutiva (intervalos parto-primeiro cio e parto-primeira inseminaçäo, número de serviços por concepçäo e período de serviço). Foram usadas 252 vacas Holandesas, paridas há mais de 30 dias e näo inseminadas. Realizaram-se medidas anatômicas da regiäo pélvica e do aparelho genital e cultivo bacteriológico de material uterino. A influência das variáveis independentes (mensuraçöes) sobre a presença de contaminantes intra-uterinos foi analisada por meio de regressäo logística, a da presença de contaminantes intra-uterinos sobre a eficiência reprodutiva, por análise de variância, e a das variáveis independentes (mensuraçöes) sobre a eficiência reprodutiva por meio de regressao linear múltipla. A presença de contaminantes intra-uterinos näo foi influenciada por nenhuma das variáveis. Staphylococcus sp. (29,6 por cento) foi o microrganismo mais encontrado no material uterino, seguido por Actinomyces pyogenes (26,0 por cento), Streptococcus sp. (22,2 por cento) e coliformes (22,2 por cento), porém essa contaminaçäo nao teve efeito negativo nos índices reprodutivos. Das medidas anatômicas avaliadas, as que influenciaram as características reprodutivas foram: abertura do ílio (maior abertura menor eficiência reprodutiva), localizaçäo do óstio cranial da cérvice (quanto mais abdominal, piores os índices reprodutivos) e presença de urovagina (influência negativa na taxa de concepçäo)