Maintenance energy requirements were estimated in two gestation and one lactation feeding trials for three groups of cows. All cows in the second gestation trial completed the first gestation and lactation trials. The three groups were chosen to represent cattle similar in growth rate and mature size but different in amount of milk provided to their calves. The low (L) group included Hereford x Angus, the medium (M) group included Red Poll x Angus and the high (H) group included Milking Shorthorn x Angus cows. Cows were individually fed to maintain net body weight (minus gravid uterus for gestation) constant. Allowances were made in energy intake for gestation and lactation. Cow weights were adjusted to an average condition score in each trial. Daily maintenance requirements during gestation were 18% lower than those during lactation. The H and M cows required 12% more energy per unit metabolic weight than L cows to maintain body weight during both gestation and lactation. Differences in milk production explained 23% of the variation in maintenance requirements, suggesting that important differences exist beyond those associated with milk production potential. Repeatabilities of maintenance requirement measurements ranged from .44 to .64. Maintenance requirements for calves under feedlot conditions in the postweaning phase were estimated from data collected from 494 calves, half-sibs and offspring of the cows described previously. Energy requirements were 11% higher for the H and M groups than for the L group.

This study aims at investigating genomic diversity of several turkey populations using Copy Number Variants (CNVs). A total of 115 individuals from six Italian breeds (Colle Euganei, Bronzato Comune Italiano, Parma e Piacenza, Brianzolo, Nero d’Italia, and Ermellinato di Rovigo), seven Narragansett, 38 commercial hybrids, and 30 Mexican turkeys, were genotyped with the Affymetrix 600K single nucleotide polymorphism (SNP) turkey array. The CNV calling was performed with the Hidden Markov Model of PennCNV software and with the Copy Number Analysis Module of SVS 8.4 by Golden Helix®. CNV were summarized into CNV regions (CNVRs) at population level using BEDTools. Variability among populations has been addressed by hierarchical clustering (pvclust R package) and by principal component analysis (PCA). A total of 2,987 CNVs were identified covering 4.65% of the autosomes of the Turkey_5.0/melGal5 assembly. The CNVRs identified in at least two individuals were 362—189 gains, 116 losses, and 57 complexes. Among these regions the 51% contain annotated genes. This study is the first CNV mapping of turkey population using 600K chip. CNVs clustered the individuals according to population and their geographical origin. CNVs are known to be indicators also of adaptation, as some researches in different species are suggesting.

Biological efficiency of beef production to weaning and to slaughter was estimated in three groups of cattle reasonably similar in growth and mature size but different in the amount of milk available to the calves (low (L) = Hereford x Angus, medium (M) = Red Poll x Angus and high (H) = Milking Shorthorn x Angus). Efficiency was defined as the ratio of estimated kilograms of calf weight weaned or carcass weight produced by a herd of 100 first-cross cows to estimated metabolizable energy (ME) intake by the cows and preweaning non-milk ME intake by the calves or preweaning non-milk and postweaning ME intake by the calves. Efficiencies were estimated assuming observed and average reproductive rates, and using observed energy requirements for maintenance, as well as the same requirements for maintenance in the M and H groups. With the observed reproductive rates and requirements for maintenance, efficiencies to weaning and to slaughter were 28.1, 27.4 and 27.4 g weaning weight per Mcal ME and 22.0, 20.6 and 20.3 g carcass weight per Mcal ME for the L, M and H groups, respectively. With average requirements for maintenance, efficiencies were 28.2 and 27.5 to weaning and 20.8 and 20.4 to slaughter for the M and H groups, respectively. Under equal reproductive rates and observed maintenance requirements, efficiencies were 28.3, 27.2 and 27.7 to weaning, and 22.1, 20.6 and 20.6 to slaughter for the L, M and H groups, respectively. With average maintenance requirements, efficiencies were 27.5 and 27.4 to weaning and 20.7 and 20.5 to slaughter for the M and H groups, respectively. Across the production output and input assumption scenarios, the L group consistently was the most efficient, especially when evaluated at slaughter of calves.

The dietary intake of total arsenic (tAs), inorganic arsenic (iAs) and total mercury (tHg) in lunch and breakfast servings provided by the Chilean School Meal Program (SMP) was estimated, using the duplicate-portion variant of the total diet study. Lunch and breakfast samples were collected from 65 schools throughout the country in 2006. The population sample was a group of girls and boys between 6 and 18 years old. The tAs concentration was measured via hydride-generation atomic absorption spectrometry. The total mercury concentration was measured via cold-vapor atomic absorption spectroscopy. The estimated iAs intake was 12.5% (5.4 μg/day) of the Provisional tolerable daily intake (PTDI) as proposed by the FAO/WHO, and the tHg intake was 13.2% (1.9 μg/day) of the PTDI as proposed by the FAO/WHO. It was therefore concluded that tAs, iAs and tHg intake from food provided by the SMP do not pose risks to student health.

Reproductive performance and body weights were studied in 81, 79 and 88 spring-calving beef cows from three groups, reasonably similar in growth rate and mature size but different in level of milk production (low [L] = Hereford x Angus, medium [M] = Red Poll x Angus and high [H] = Milking Shorthorn x Angus). Milk group did not have a significant effect on dates of first postpartum estrus and first and last breeding or in the intervals from calving to first estrus, to first breeding and to last breeding. A significant age-of-cow x milk-group interaction was found for pregnancy rate (PR, P less than .10) and calf-crop percentage (CC, P less than .05). In heifers, PR and CC were lowest for the L (85.6 and 73.6%) and highest for the M group (94.2 and 92.5%); in 2-yr-olds there were no differences, and in older cows, PR was highest for the L (94.8%) and lowest for the H group (91.6%), and there were no differences in CC. As estimated from Brody's growth curves, mature sizes were 530 +/- 5.7, 471 +/- 4.6 and 499 +/- 4.2 kg for the L, M and H groups, respectively. Of weights taken on four occasions during the year, October weight was the highest for all cows. February weight, minus the estimated gravid uterus weight, was the lowest for L and M cows, and May weight was lowest for H cows. Weight fluctuation over an annual cycle was greatest for the L group. Under these experimental conditions, cows in all groups were able to consume sufficient energy and gain or lose body reserves to achieve similar reproductive performance while differing in lactation performance.