Plasma and milk metabolomics revealed changes in amino acid metabolism in Holstein dairy cows under heat stress.

Our understanding of metabolic alterations triggered by heat stress is incomplete, which limits the designing of nutritional strategies to mitigate negative productive and health effects. Thus, this study aimed to explore the metabolic responses of heat-stressed dairy cows to dietary supplementation with vitamin D3/Ca and vitamin E/Se. Twelve multiparous Holstein cows were enrolled in a split-plot Latin square design with two distinct vitamin E/Se supplementation levels, either at a low (ESe-, n = 6, 11.1 IU/kg vitamin E and 0.55 mg/kg Se) or a high dose (ESe+, n = 6 223 IU/kg vitamin E and 1.8 mg/kg Se) as the main plot. Treatment subplots, arranged in a replicated 3 × 3 Latin square design, comprised heat challenge (Temperature Humidity Index, THI: 72.0-82.0) supplemented with different levels of vitamin D3/Ca: either low (HS/DCa-, 1 012 IU/kg and 0.73%, respectively) or high (HS/DCa+, 3 764 IU/kg and 0.97%, respectively), and a pair-fed control group in thermoneutrality (THI = 61.0-64.0) receiving the low dose of vitamin D3/Ca (TN). The liquid chromatography-mass spectrometry-based metabolome profile was determined in blood plasma and milk sampled at the beginning (day 0) and end (day 14) of each experimental period. The results were analyzed for the effect of (1) TN vs. HS/ESe-/DCa-, and (2) the vitamin E/Se and vitamin D3/Ca supplementation. No group or group × day effects were detected in the plasma metabolome (false discovery rate, FDR > 0.05), except for triglyceride 52:2 being higher (FDR = 0.03) on day 0 than 14. Taurine, creatinine and butyryl-carnitine showed group × day interactions in the milk metabolome (FDR ≤ 0.05) as creatinine (+22%) and butyryl-carnitine (+190%) were increased (P < 0.01) on day 14, and taurine was decreased (-65%, P < 0.01) on day 14 in the heat stress (HS) cows, compared with day 0. Most compounds were unaffected by vitamin E/Se or vitamin D3/Ca supplementation level or their interaction (FDR > 0.05) in plasma and milk, except for milk alanine which was lower (-69%, FDR = 0.03) in the E/Se+ groups, compared with E/Se-. Our results indicated that HS triggered more prominent changes in the milk than in the plasma metabolome, with consistent results in milk suggesting increased muscle catabolism, as reflected by increased creatinine, alanine and citrulline levels. Supplementing with high levels of vitamin E/Se or vitamin D3/Ca or their combination did not appear to affect the metabolic remodeling triggered by HS.

Helminth parasites of finfish commercial aquaculture in Latin America.

Latin America has tripled production by aquaculture up to 78 million tonnes in the past 20 years. However, one of the problems that aquaculture is facing is the presence of helminth parasites and the diseases caused by them in the region. In this review we have collected all the available information on helminths affecting commercial aquaculture in Latin America and the Caribbean (LAC), emphasizing those causing serious economic losses. Monogeneans are by far the most common and aggressive parasites affecting farmed fish in LAC. They have been recognized as serious pathogens in intensive fish culture because they reach high levels of infection rapidly, and can infect other phylogenetically related fish species. The next most important group comprises the larval stages of digeneans (metacercariae) such as Diplostomum sp. and Centrocestus formosanus, which cause serious damage to farmed fish. Since LAC aquaculture has been based mainly on exotic species (tilapia, salmon, trout and carp), most of their parasites have been brought into the region together with the fish for aquaculture. Recently, one of us (A.I.P.-T.) has suggested that monogeneans, which have generally been considered to be harmless, can produce serious effects on the growth of cultured Nile tilapia. Therefore, the introduction of fish together with their 'harmless' parasites into new sites, regions or countries in LAC should be considered a breakdown of biosecurity in those countries involved. Therefore, the application of quarantine procedures and preventive therapeutic treatments should be considered before allowing these introductions into a country.

Association of SNP of neuropeptide Y, leptin, and IGF-1 genes with residual feed intake in confinement and under grazing condition in Angus cattle.

In this study we quantify and compare the phenotypic variation in residual feed intake (RFI) in 2 groups of Angus female calves: one carrying simultaneously putative favorable allelic variants (SNP) of neuropeptide Y, leptin, and IGF-1 genes (VAL group) and another devoid of such alleles (CON group). We performed 2 sequential trials: under confinement feeding a high-concentrate diet and under grazing condition. In confinement, 38 purebred Angus female calves [mean age and BW of 247 d (SD = 15) and 186 kg (SD = 33.2), respectively] were offered a total mixed ration diet (60:40 concentrate: alfalfa hay, as fed) ad libitum during 57 d. Dry matter intake was estimated from the difference between offered and refused feed; BW was recorded every 2 wk. Under grazing, 12 heifers from each group were ranked by BW and RFI and randomly assigned to 4 pasture paddocks. Heifers were continuously stocked at high-quality, high-herbage-mass mixed pasture. Herbage DMI was determined using the n-alkane technique. Different models were used to determine RFI: models that use phenotypic data [RFI as described by Koch et al. (1963; RFIK) and RFI as described by ME (RFIME)] and models that use standards feeding data [RFI estimated by Fan et al. (1995; RFIF) and RFI in which the expected DMI was derived from equations in Standing Committee on Agriculture (1990; RFISCA)]. Least squares mean values (SE) of DMI (kg/d), metabolizable energy intake (MEI; Mcal/d), ADG (kg), RFIK (kg DM/d), and feed conversion ratio (FCR; kg DMI/kg ADG) for VAL and CON genotype groups were 6.65 and 6.89 (0.49), 16.7 and 17.4 (1.44), 1.24 and 1.24 (0.03), -0.11 and 0.11 (0.09), and 5.8 and 5.8 (0.14), respectively, in the confinement trial. In the grazing trial least squares mean values (SE) of herbage DMI (kg/d), ADG (kg), MEI (Mcal/d), RFIK, and FCR of VAL and CON groups were 8.76 and 10.93 (0.71), 1.4 and 1.37 (0.05), 25.5 and 31.7 (2.09), -1.02 and 1.02 (0.42), and 6.41 and 6.96 (0.46), respectively. Genotyped groups tended to differ in DMI (P = 0.10), in MEI (P = 0.06), and in RFIK (P = 0.10), differed in RFIF (P = 0.010), and did not differ in ADG or FCR during confinement. During grazing, genotyped groups differed in DMI (P = 0.005), in MEI (P = 0.006), and in RFIK (P = 0.002) but did not differ in ADG and FCR. Our results demonstrate a strong association between these 3 SNP and RFI when animals were grazing on a high-quality, high-availability pasture, whereas a weak effect was observed under confinement.