Effects of metabolizable energy intake on post weaning lamb growth performance, carcass tissue composition and internal fat depend on animal characteristics: A meta-analysis

Low-Density Polyethylene Microplastics in the Rumen: Implications for Rumen Fermentation Dynamics and Utilization of Concentrate Feed

Microplastics (MPs) have emerged as a significant environmental threat, infiltrating livestock systems. This study presents the first in vitro investigation of the effects of low-density polyethylene (LDPE) MP contamination on rumen fermentation dynamics and feed utilization in a simulated ruminal digestive system. Concentrate feed was incubated in buffered rumen fluid collected from lambs, supplemented with LDPE MPs at concentrations of 3.3 g/L and 6.6 g/L and compared to the concentrate incubated in the buffered rumen fluid without MP contamination. The results demonstrate that both levels of LDPE MPs significantly altered rumen fermentation dynamics by reducing asymptotic gas production by 11% and 15% and increasing the constant rate of gas production by 16% and 19% at low and high addition levels, respectively, compared to the control. However, the early-stage fermentation dynamics remained unaffected. Furthermore, both levels of LDPE MPs reduced rumen protozoal populations (20% and 23%) and ammonia-nitrogen levels by 11% at both of addition levels. Despite these disruptions, rumen pH remained unaffected. Increasing the addition level of LDPE from 3.3 to 6.6 g/L did not exacerbate the disruptions. The results of this study highlight the potential risks posed by LDPE MPs in ruminal nutrition. Further in vivo investigations are essential to validate these findings and assess their impact on animal performance.

Effects of refused melon fruit in Canarana grass ensilage on intake, digestibility, serum biochemistry, performance, carcass characteristics and meat attributes of feedlot lambs

Ensilage of refused fruit with forage is a viable approach to increase resource use in ruminant feed. The objective of this study was to investigate the impact of ensiling refused melon fruit (RMF) with Canarana grass on the intake, apparent digestibility, serum biochemistry, performance, carcass traits, and meat attributes of feedlot lambs. Four distinct silage treatment types were prepared by ensiling RMF at 0 g/kg (control), 70 g/kg, 140 g/kg, and 210 g/kg (as fed) with Canarana grass. Twenty-eight male Santa Inês lambs (7 lambs per treatment), initially weighing 22.3 ± 1.0 kg at 120 days of age, were distributed in a completely randomized design and confined for a total of 96 days, including a 23-day adaptation period and 73 experimental days in a feedlot. The lambs received the treatment-silage in diets as a complete mixture with a roughage: concentrate ratio of 30:70. The inclusion of RMF in Canarana grass ensilage decreased (P < 0.05) the lambs' intake of dry matter, crude protein and metabolisable energy. The inclusion of RMF in ensilage had a quadratic effect (P < 0.05) on the digestibility of non-fibrous carbohydrates. The serum total protein and cholesterol levels decreased (P < 0.05) with the inclusion of RMF in the ensilage, but we observed no effect on the final weight and average daily gain of the lambs. The feed efficiency increased (P < 0.05) by including RMF in the Canarana grass ensilage. The RMF in the ensilage did not influence cold carcass weight and yield. The fat content of the meat decreased (P < 0.05) with the inclusion of RMF in the ensilage. It is recommended the inclusion of up to 210 g/kg of RMF in Canarana grass ensilage to increase feed efficiency and avoid impacts on the performance and carcass attributes of confined lambs.

Orange molasses as a new energy ingredient for feedlot lambs in Brazil

The objectives of this experiment were to evaluate the effects of increasing levels of orange molasses in replacement of flint corn grain in high-concentrate diets on dry matter intake (DMI), average daily gain (ADG), and feed efficiency (FE) of feedlot lambs. Thirty male lambs without defined racial pattern (30.3 ± 5.3 kg of initial BW; mean ± SD) were used in a randomized complete block design with 10 blocks and 3 treatments. The treatments were defined by partial replacement of flint corn by orange molasses in the diet with 90% of concentrate and 10% of Cynodon spp. hay, as follows: 0OM-control diet without orange molasses; 20OM-20% of orange molasses replacing flint corn; and 40OM-40% of orange molasses replacing flint corn (DM basis). The experiment lasted 72 days divided into 3 subperiods, with 1 subperiod of 16 days and 2 subperiods of 28 days. Animals were weighed after a 16-h fast on days 1, 16, 44, and 72 of the experimental periods to determine the ADG and FE. The DMI, ADG, and FE showed an interaction between treatments and experimental periods. The DMI in the first period decreased linearly (P < 0.01); in the third period, there was no effect of treatments (P > 0.05) on DMI. The ADG decreased linearly (P < 0.01) in the first period as the orange molasses increased. Otherwise, in the third period, ADG increased linearly (P = 0.05) as flint corn was replacement by orange molasses. The FE showed an interaction between treatment and period (P = 0.09). The first period had a decreased linear effect; in the third period, there was a trend (P = 0.07) of increased linear effect. There was no difference between the diets regarding the final BW of the lambs. In conclusion, the orange molasses can replace up to 40% of flint corn in diets for feedlot lambs without affecting final BW. However, it is important to consider the adaptation time proved to be very important for better use of orange molasses as a source of energy in diets for lambs.

Development and Application of a High-Resolution Melting Analysis with Unlabeled Probes for the Screening of Short-Tailed Sheep TBXT Heterozygotes

Simple Summary

TBXT (c.333G > C; c.334G > T) has been identified as a molecular genetic marker in short-tailed sheep. This paper describes a high-resolution melting (HRM) analysis using unlabeled probes and asymmetric PCR for the detection of genetic variants of TBXT in short-tailed sheep populations. The detection results of this method are consistent with those of Sanger sequencing and can help farmers with marker-assisted breeding.

Abstract

The short-tailed phenotype has long been considered one of the best traits for population genetic improvement in sheep breeding. In short-tailed sheep, not only is tail fat eliminated but also the pubic area is exposed due to the lack of a tail covering, giving them an advantage in reproduction. Recent studies have shown that two linked mutations in sheep TBXT at nucleotides 333 and 334 are associated with the short-tailed phenotype. In the population of short-tailed sheep, several heterozygous mutants of this gene are found. In our research, we used high-resolution melting (HRM) to identify homozygous and heterozygous genotypes in a flock of short-tailed sheep and compared the results with those of Sanger sequencing, which were identical. This demonstrates that our established HRM method, a rapid and inexpensive genotyping method, can be used to identify homozygous and heterozygous individuals in short-tailed sheep flocks.