Fatty acid profile, oxidative stability of pork lipids and meat quality indicators are not affected by birth weight.

The aim of this study was to investigate whether fatty acid (FA) profile, oxidative stability of lipids and other meat quality traits differed between high (HW: 1.8 to 2.2 kg) and low (LW: 0.8 to 1.2 kg) birth weight piglets. Forty new-born male pigs (n=20 HW, n=20 LW) were reared in separate pens until the finishing period, when they were slaughtered at 150 days of age, and pH and temperature were measured in the carcass. Afterwards, the Longissimus dorsi muscle was excised from the carcass, and samples were collected for subsequent meat quality analyses (thaw loss, cooking loss, shear force, chemical analysis and sensory analysis for tenderness). Birth weight had minor impacts on meat quality traits, which were limited to higher shear force in the LW group (P<0.01). Chemical components (moisture, protein, fat, ash), cholesterol levels and lipid oxidation (thiobarbituric acid-reactive substances) were not affected by birth weight (P>0.05). FA profile and the amount of saturated, monounsaturated and polyunsaturated fatty acids were similar, but HW pigs had higher atherogenic index than their LW counterparts (P<0.01). Notwithstanding the higher shear force presented by the lower birth weight pigs, in the sensory test, the panelists did not detect any differences in the tenderness of pork from HW and LW animals. Therefore, our results suggest that low birth weight has minimal impact on meat quality.

Intra-uterine growth retardation affects birthweight and postnatal development in pigs, impairing muscle accretion, duodenal mucosa morphology and carcass traits.

The present study investigated the occurrence of intra-uterine growth retardation (IUGR) in newborn (n=40) and 150-day-old (n=240) pigs of different birthweight ranges (high, HW: 1.8-2.2kg; low, LW: 0.8-1.2kg) from higher-parity commercial sows and its impact on their subsequent development and carcass traits in a Brazilian commercial production system. HW newborn pigs had heavier organs than LW pigs (P<0.01), and all brain:organ weight ratios were higher (P<0.01) in LW compared with HW offspring, providing strong evidence of IUGR in the LW piglets. HW pigs had higher bodyweights and average daily gain (ADG) in all phases of production (P<0.05), but ADG in the finisher phase was similar in both groups. Additionally, LW newborn and 150-day-old pigs showed a lower percentage of muscle fibres and a higher percentage of connective tissue in the semitendinosus muscle, greater fibre number per mm(2) and a lower height of the duodenal mucosa (P<0.05). On the other hand, HW pigs had higher hot carcass weight, meat content in the carcass and yield of ham, shoulder and belly (P<0.01). Hence, lower-birthweight piglets may suffer from IUGR, which impairs their growth performance, muscle accretion, duodenal mucosa morphology and carcass traits.

Desarrollo e histología testicular de gallos ligeros sometidos a diferentes fotoperiodos / Development and testicular histology of light roosters submitted to different photoperiods

Con el objetivo de evaluar los efectos de diferentes fotoperiodos sobre el desarrollo e histología testicularde gallos ligeros, se realizó un experimento en el Departamento de Zootecnía de la Universidade Federalde Lavras. Fueron utilizados 48 gallos de linaje Lohman LSL con una edad inicial de 133 días, que fueron sometidos a 3 tratamientos: 1) Fotoperiodo Continuo; 2) Fotoperiodo Intermitente y 3) Fotoperiodo NaturalCreciente. Tanto la asignación a los grupos experimentales como la selección de los animales para sacrificio se realizo aleatoriamente. El periodo experimental tuvo una duración de 140 días. Las variables evaluadas fueron el peso corporal y peso de los testículos derecho (PTD) e izquierdo (PTE), en gramos; el diámetro de los tubos seminíferos (DTS) y el espesor del epitelio seminífero (EES), en micrómetros, y, el número de células delos tubos seminíferos (células de Sertoli, espermatogonias y espermátides redondeadas). Las diferencias entre tratamientos fueron comparadas por la prueba Scott Knott (5%). No se observó efecto significante (P>0,05) delos fotoperiodos y de las edades sobre las variables evaluadas, con excepción del número de espermatogonias que presentó aumento inicial y disminución progresiva a partir de los 203 días. Se concluyó que los fotoperiodos continuo, intermitente o natural creciente pueden ser utilizados para los gallos ligeros durante el periodo reproductivo, sin prejuicio para los parámetros testiculares. Debido al menor gasto energético que puede ser conseguido con la utilización del fotoperiodo natural creciente, este seria el programa más recomendado para los machos, con relación a las características testiculares

With the objective of evaluating the effects of different photoperiods on the development and testicular histology of light roosters, an experiment was conducted in the Animal Science Department of the Federal University of Lavras. 48 roosters of the Lohman LSL strain, aged 133 days were utilized, they themselves being submitted to 3 treatments: 1) Continuous photoperiod, 2) Intermittent photoperiod and 3) Growing natural photoperiod. The animals were allotted to a completely randomized experimental design, with 4 replicates being the experimental unit being made up of 1 animal. The experimental period lasted 140 days and the variables evaluated were: body weight, weights of the right (PTD) and left testes (PTE), in grams; diameter of the seminiferous tubules (DTS) and thickness of the seminiferous epithelium (EES), in micrometers and number of cells of the seminiferous tubules (Sertoli cells, rounded spermatogonia and spermatids). The differences between treatments were compared by the Scott Knott test (5%). A significant effect was not observed (P>0.05) of the photoperiods and the ages on the analyzed variable, with exception of the number of spermatogonia that had presented quadratic variation with the increase of the age of the animals. It follows that photoperiods continuous, intermittent or growing natural light can be utilized for creation of light roosters over the reproductive period without harming the testicular parameters. Had to the lesser expense of energy that can be gotten with the use of Growing natural photoperiod, this would be the recommended program more for themales, with regard to the testicular characteristics